Deutsche Physikerinnentagung 2026

28 Sept 2026, 08:00 → 30 Sept 2026, 19:30 Europe/Berlin

Kaiserslautern

The German Conference of Women in Physics (Deutsche Physikerinnentagung) will be hosted in 2026 by the Rheinland-Pfälzische Technische Universität (RPTU) Kaiserslautern-Landau at the campus in Kaiserslautern.

The scientific focus of the conference is on solid state, bio, and spin physics, as well as photonics and quantum technologies. We also welcome contributions on physics ranging from very small to very large scales in energy, time, and space, from elementary particle physics to cosmology.

The scientific program will be complemented by events on careers in industry, soft skills workshops, and opportunities to meet representatives from industry and research and to network.

The conference is conducted in English and supported by the Working Group on Equal Opportunities (AKC) of the Deutsche Physikalische Gesellschaft (DPG).

For further questions, please contact dpt2026@rptu.de

 

Confirmed speakers include:

• Keynote speaker Prof. Dr. Karin Jacobs, Saarland University
• Public plenary talk Prof. Dr. Sibylle Günter, Max Planck Institute for Plasma Physics Greifswald
• Keynote speaker Prof. Dr. Monika Ritsch-Marte, Medical University of Innsbruck
• Keynote speaker Dr. Maria Azhar, The University of Duisburg-Essen (Hertha-Sponer-Preisträgerin 2026)
• Dr. Andrea Bergschneider, University of Bonn
• Prof. Dr. Maria Dienerowitz, University of Applied Sciences Jena
• Dr. Zlata Fedorova, Friedrich Schiller University Jena
  
• Prof. Dr. Katharina J. Franke, Freie Universität Berlin
  
• Prof. Dr. Anja Metelmann, Karlsruhe Institute of Technology
• Prof. Dr. Giovanna Morigi, Saarland University
• Jun.-Prof. Dr. Iris Niehues, University of Münster
• Prof. Dr. Silke Bühler Paschen, Vienna University of Technology
• Dr. Pauline Rovillain, Centre national de la recherche scientifique Paris
• Prof. Dr. Julia Stähler, Humboldt-Universität zu Berlin
  
• Prof. Dr. Dr. hc. Viola Vogel, ETH Zurich
• Dr. Gesa Welker, Delft University of Technology
• Jun.-Prof. Dr. Angela Wittmann, Johannes Gutenberg University Mainz

 

Gold sponsors:

     

 

Silver sponsors:

 

 

Bronze sponsors:

   

 

This conference is also kindly supported by:

     

     

 

 

DPT26_RPTU.pdf

Monday 28 September

Registration

Workshop: Career Development for Early-Career Physicists: Exploring Options in Research and Innovation

Participation is limited to those who have registered for the workshop in advance

Convener: Anke Soemer

Workshop: Science Communication for Physicists – Presenting Research with Clarity and Confidence

Participation is limited to those who have registered for the workshop in advance

Convener: Sabrina Patsch

Workshop: Scientific Writing / Author Workshop with OPTICA

Participation is limited to those who have registered for the workshop in advance

Convener: Claus Roll

Workshop: Starke Frauen - Selbstbewusstes Auftreten

Participation is limited to those who have registered for the workshop in advance

Convener: Silke Gorges

Company Exhibition Monday

12:30 Lunch

Conference Opening

Convener: Elke Neu-Ruffing (RPTU Kaiserslautern-Landau, Fachbereich Physik)

1 Eröffnung und Grußworte

2 Keynote I (Prof. Karin Jacobs): I am in the right place: How young female physicists find their way — and change physics

“You must be in the wrong place!” — this was how my interview talk for a professorship in physics began more than twenty years ago. Since then, much has changed. Female physicists have become more visible, gender equality has become an important aspect of appointment procedures, funding programs, and scientific committees, and questions of work-life balance, dual careers, leadership, and fair career paths are no longer seen simply as “women’s issues.”

And yet, one central question remains: When do young female physicists really feel that they are in the right place — in physics, in science, in interdisciplinary research, and in the committees where the future of science is shaped?

This talk combines personal experiences with a look at structural changes over the past two decades. It asks what role models, visibility, good supervision, fair negotiations, early scientific independence, and a culture of trust and encouragement can contribute. There are no simple recipes for a successful career. What matters is creating an environment in which different people can find their own way and different life and career paths are possible.

Physics itself is changing. It is becoming more interdisciplinary, more collaborative, and more relevant to society. This change offers an opportunity. When young female physicists are not only invited to participate, but are encouraged to take responsibility and shape the future of their field, they do more than find their own way in physics — they change physics

Speaker: Karin Jacobs (Universität des Saarlandes)

15:00 Coffee Break

Physics and Society (Invited talk Melanie Steffens, Tamar Grosz, Paula Becker)

Convener: Zuzana Storchova

3 In/Visibility of women in quantum technologies: preliminary findings of the WomenInQuantumTech project

Equal participation of highly qualified women in quantum technology has not yet been achieved. Although quantum technologies are considered key technologies and receive significant funding, women remain significantly underrepresented in related fields such as physics, computer science, and certain engineering disciplines.
Furthermore, the few women in these fields are often less visible than their male colleagues. This lack of visibility affects both visibility and recognition within the scientific community and visibility outside the academic sphere, such as the public sphere, business, politics, and the media. Visibility within the discipline manifests itself, for example, in practices of recognition and appreciation, such as the awarding of prizes, honors, invitations to give lectures, or taking on leadership positions. At the same time, it forms an important basis for visibility outside the discipline.
Research about disciplinary culture in the field of gender studies in STEM shows that implicit processes of inclusion and exclusion are at work in scientific communities. These are also evident in practices that render women (in)visible or keep them (in)visible. Ensuring that outstanding female researchers in key technologies, such as quantum technologies, are recognized does not only involve women gaining more visibility but also being recognized as worthy of such visibility by their community. Therefore, it is not enough to rely solely on individual strategies. Rather, changes to the structures and cultures of research itself are crucial.
This talk presents the initial findings of the BMFTR-funded “WomenInQuantumTech”. The research focuses on investigating the mechanisms that influence the visibility and participation of women in quantum technologies and developing strategies to improve their visibility, in collaboration with female researchers.

Speaker: Tamar Grosz (Freie Universität Berlin)

4 Girls into STEM: Which interventions work?

During the past decades, researchers have identified many factors crucial for the development of interests, ability self-concepts, and eventually career choice. Concurrently, practitioners have developed and implemented short- and long-term intervention programs to foster girls’ and young women’s interest in STEM fields (Science, Technology, Engineering, and Math). Some of these are theoretically informed and others are not, and they capitalize on various factors (e.g., role models, hands-on experiences, mentoring, gender segregation). Some evaluations of these interventions exist, for different age groups, on various outcome levels, with different scientific quality (e.g., randomized control trials vs. pre-post measurement), and in different contexts (laboratory-based vs. applied) and cultures. The aim of the present paper is to provide a critical review on interventions that try to increase girls’ interest in STEM fields: How strong is the evidence regarding different factors? We will critically evaluate this. Can recommendations be deduced from this evidence, such as: Which age group(s) should be targeted? How long should interventions last? Are different interventions needed for different domains? Have any factors been overlooked? We are planning to conduct a meta-analysis summarizing the available evidence. That way, we hope to provide guidelines for practice in addition to an agenda for future research.

Speaker: Melanie Steffens (RPTU University Kaiserslautern-Landau)

5 Who Sees Themselves in Physics? And Why (Not)?

Insights from Physics Identity Research for Educational Practice
The underrepresentation of different social groups in physics has been the subject of research for decades. Yet, the questions Who decides to engage in physics? and Which factors shape these decisions? remain highly relevant.
Within physics education research, physics identity theory (PIT) has become an established framework for conceptualising this multilevel problem. Bringing together different strands of research, PIT holistically approaches participation in physics as a complex interplay between individual factors (such as interest) and the societal and social contexts (e.g. recognition by teachers) in which engagement with physics takes place.
This contribution seeks to provide an introduction to the physics identity framework and resulting insights on how and why students do (not) engage with physics. In fact, an implementation gap seems to limit the translation of what research tells us about the development of physics identities into educational practice. Interventions designed to broaden participation in physics—such as project weeks, outreach activities, or programs in schools—are often only loosely grounded in theoretical and empirical evidence and are rarely evaluated systematically. We therefore present current research projects that aim to further understand physics identity development and explore how to make these findings usable for practice.

Speaker: Paula Becker

6 Die Geschichte von AKC und DPT

Mit diesem Beitrag stellen wir Euch den Arbeitskreis Chancengleichheit (AKC) vor, eine fachübergreifende Vereinigung innerhalb der Deutschen Physikalischen Gesellschaft (DPG) mit über 850 Mitgliedern. Das Ziel des AKC ist die Verbesserung der Rahmenbedingungen und Strukturen für Frauen in der Physik zur Erreichung von Chancengleichheit in Ausbildung und Beruf. Hierzu gehört auch die jährlich stattfindende Physikerinnentagung. Die Tagung stellt eine Plattform zum Kennenlernen und Austausch dar, und sie erhöht so die Sichtbarkeit von Physikerinnen. Im Vortrag geben wir einen Überblick über die Geschichte des AKCs und der DPT von der Idee über die Gründung bis zum heutigen Zeitpunkt. Dabei zeigen wir zahlreiche Meilensteine auf, beginnend mit der Schaffung des AKCs und der DPT. Wir benennen die vielfältigen Aufgaben, die unsere Kommission und ihre Unterstützerinnen bearbeiten. Für die Gestaltung der Zukunft brauchen wir Euch, bitte teilt uns Eure Meinung, Wünsche und Ziele mit.

Speaker: Agnes Sandner

Physics@Work I

Convener: Mareike Schäfer

7 Isabel @ work

Dr. Isabel Barbosa is a Laser Engineer at Marvel Fusion, a DeepTech company based in Munich, aiming to commercialize fusion energy.
Isabel’s academic career focused on interdisciplinary research, with a Bachelor’s and Master’s degree in Chemistry and a PhD in Physics. Her current work at Marvel Fusion focuses on optical components, such as mirrors and gratings, for high-energy environments, investigating the damage thresholds of these optics under extreme conditions.
These studies will provide vital insights into the underlying damage mechanisms and contribute to enabling high-energy lasers for fusion applications.

Speaker: Isabel Barbosa (Marvel Fusion GmbH)

8 TOPTICA Photonics SE: We make the best Photons

TOPTICA Photonics SE is a leading provider of high-end laser systems for scientific and industrial applications, with technologies used in quantum technologies, biophotonics, materials processing, and metrology. The TOPTICA Group employs over 600 professionals across seven corporate entities.
In this talk, I will share my personal path from Physics studies at university into industry and discuss my current role as a Technical Sales Expert at TOPTICA. Furthermore, through examples from female colleagues across different departments of the company, the presentation will highlight the different roles physicists can take on beyond academia, from research and development, production, product management, or service. The talk aims to provide insight into how physicists contribute to modern photonics industries and help shape future technologies.

Speaker: Jennifer Koch (TOPTICA Photonics SE)

9 neQxt – working in a company to build quantum computers

As a PhD student I imagined research in industry to be very different than in academia. That certainly holds true for many companies. However, in a cutting-edge field like quantum computing, there are startups which pursue research questions which are actually very similar to those discussed at universities. neQxt is such a startup that offers positions where the daily activities are similar to those found in academic settings while providing the advantages of working in the industry. Personally, I was a PhD specialised in quantum information theory, and thus, neQxt was the ideal place for me to join.

neQxt is a full-stack quantum computing company. As a spin-off from the Schmidt-Kaler group at Johannes Gutenberg University Mainz, it embodies decades of experience in the field of ion trap quantum computers. The startup spans the entire spectrum from hardware production to software development. This includes a theory team focused on quantum error correction and algorithms, where I found my niche within the company.

In my presentation, I will introduce the company neQxt, discuss my work in the theory team, and explain how I decided to join neQxt as a quantum error correction researcher.

Speaker: Lina Vandré (neQxt, TU Wien)

10 Auf Expedition durch die Rushhour des Lebens

Plötzlich ist viel gleichzeit los im Leben: Uniabschluss, Berufseinstieg, Karriereentwicklung, Familiengründung, um die Eltern kümmern, neue Freundschaften finden, sich als Paar nicht verlieren und das alles unter Zeitdruck und mit Schalfmangel. Kann man sich auf diese Expedition vorbereiten? Anhand meines beruflichen Weges möchte ich beschreiben, welche Ratschläge und Tipps mir geholfen haben.
Nach meiner Promotion und meiner prägenden Zeit am Fraunehofer IESE arbeite ich nun seit fast 10 Jahren in der Digitalisierung für BASF. Nach dem Start in der Forschung, ging ich als Gruppenleiterin mit meiner Familie auf eine Delegation nach Houston, TX und bin aktuell für die stategische Umsetzung von Digitalisierung in unseren chemischen Betrieben in Ludwigshafen verantwortlich.

Speaker: Astrid Niederle

Scientific Session I (Invited talk Pauline Rovillain): Magnetism and magnetic devices

Convener: Katharina Lasinger

11 Spin waves and acoustic waves coupling in iron thin film

In the last decade the physics of spin waves has regained interest in the emerging field of magnonics. In a magnonic device, the collective precession motion of spins in a ferromagnet permits to process information at low power consumption and high operation speed in a wide frequency range from GHz to THz. Spin waves present two important features: their frequency can be easily varied by applying an external magnetic field, Bext, and their dispersion curves strongly depend on the direction of Bext with respect to the SW wave vector. Moreover, fascinating phenomena involving spin waves and phonons are observed at the magnetoelastic resonance as acoustically-assisted spin pumping [1,2] up to the acoustically driven magnetization switching [3, 4]. In this context, Surface Acoustic waves (SAW), a mature technology, triggers efficiently magnetization dynamics: resonant effects are obtained with appropriate intensities and directions of the external magnetic field (Bext). This tunability is an asset for magnonic applications of SAW-FMR (ferromagnetic resonance). I will present our results obtained in Fe epitaxially grown on GaAs(001), a spintronic and magnonic compatible magnetoelastic and piezoelectric hetero-structure.[5,6,7]

[1] M. Weiler, et al. PRL, 108, 176601 (2012)
[2] Uchida, et al., Solid State Comm. 198, 26 (2014)
[3] L. Thevenard,et al. PRB, 2016, 93, 134430 (2016)
[4] P. Kuszewski, et al. JOP: Cond. Mat., 30, 244003 (2018)
[5] J.-Y. Duquesne, et al. PR Applied, 12, 024042 (2019)
[6] P. Rovillain et al. PR Applied 18, 064043 (2022)
[7] A. Sharma et al. Appl. Phys. Letter, 128, 062404 (2026)

Speaker: Pauline Rovillain (Institut des nanosciences de Paris - Sorbonne Université)

12 Current-Induced Skyrmion Dynamics and Diffusion

Magnetic skyrmions, nanoscale chiral spin textures with particle-like behavior, are promising candidates for information storage and unconventional computing due to their robustness and efficient current-driven motion [1-3]. In Ta/CoFeB/MgO multilayers, we investigate the transition of current-driven skyrmion motion from creep, through depinning, to the viscous flow regime driven by a unipolar, pulsed current. By varying current density, pulse width, and frequency, we demonstrate how external stimulation overcomes pinning potentials and guides skyrmions into a regime characterized by linear velocity–current relations, i.e., the viscous flow regime. Additional studies with an alternating, net-zero current drive reveal an exponential increase of the diffusion coefficient with current density, while higher frequencies suppress diffusion following a power-law dependence. These findings provide quantitative insight into controlling skyrmion mobility and diffusion, essential for spintronic device design [4].
[1] G. Beneke et al., Nat. Commun., 15, 8103 (2024).
[2] K. Raab et al., Nat. Commun., 13, 6982 (2022).
[3] K. Everschor-Sitte et al., J. Appl. Phys., 124, 24, 240901 (2018).
[4] L. Dany et al., under preparation.

Speaker: Leonie-Charlotte Dany (Johannes Gutenberg-Universität Mainz)

13 Strain-induced Control on Topological Magnetic Textures in Antiskyrmion Hosting Material

In non-centrosymmetric crystal structures with $D_{2d}$ or $S_4$ symmetry, anisotropic Dzyaloshinskii-Moriya interaction (DMI) stabilizes antiskyrmions which was recently confirmed experimentally [1,2]. In these materials, easy-axis anisotropy additionally stabilizes skyrmions and non-topological bubbles in certain ranges of external magnetic fields and lamella thicknesses. The competition between magnetic dipolar interaction and DMI renders skyrmions elliptical depending on their handedness. Also, dipolar interaction stabilizes skyrmion caps on top of antiskyrmions which renders them rectangular [3]. In this work, we investigate how external mechanical strain can be used as an additional tuning parameter for the stability of these topological magnetic textures. We show that strain breaks the degeneracy of distinct types of elongated skyrmions and antiskyrmions. This can be used to controllably switch the direction of elongation of hybrid antiskyrmion with hysteresis.

References:
[1] A. Nayak et al., ‘Magnetic antiskyrmions above room temperature in tetragonal Heusler materials’, Nature 548, 561-566 (2017).
[2] K. Karube, L. C. Peng, J. Masell, et al., ‘Room-temperature antiskyrmions and sawtooth surface textures in a non-centrosymmetric magnet with S4 symmetry’, Nat. Mater. 20, 335-340 (2021).
[3] F. S. Yasin, J. Masell et al., ‘Bloch Point Quadrupole Constituting Hybrid Topological Strings Revealed with Electron Holographic Vector Field Tomography’, Adv. Mater. 36 (16), 2311737 (2024).

Speaker: Somasree Bhattacharjee (Karlsruhe Institute of Technology (KIT))

14 Erbium-doped materials for microwave-to-optical interfaces in superconducting quantum networks

Future quantum networks require interfaces that connect quantum processors over long distances. Superconducting quantum circuits are a leading platform for quantum computing, but operate with microwave-frequency signals that cannot be efficiently transmitted through optical-fiber networks (1, 2). Optical photons, by contrast, are well suited for low-loss communication over long distances and can use existing telecommunication infrastructure (3). Microwave-to-optical transducers could bridge these frequency regimes and thereby connect superconducting quantum processors through optical quantum networks (4).
We investigate this challenge using erbium-doped solid-state materials. Erbium is particularly promising because it combines magnetic spin transitions at microwave frequencies with an optical transition in the telecommunications C-band. Microwave and optical fields can therefore interact through the same ensemble of erbium ions, enabling Raman-type coherent frequency conversion (5).
We explore two distinct erbium-doped platforms: bulk crystals, which provide exceptional transition strength and narrow linewidths (6) as well as nanophotonic silicon waveguides, which combine long coherence times with CMOS compatibility and potential for integration into chip-based superconducting circuits (7).
These systems could provide an interface between superconducting quantum processors and fiber-based quantum networks, supporting the future distribution of quantum information across distant quantum devices.

(1) M. H. Devoret & R. J. Schoelkopf, Science, 339 (2013)
(2) R. Lescanne, Physics, 13 (2020)
(3) P. Holewa et al., Nanophotonics, 14 (2025)
(4) N. Lambert et al., Adv. Quantum Technol., 3 (2020)
(5) L. Williamson et al. Phys.Rev.Lett., 113, (2014)
(6) Xie et al., Phys. Rev. B., 104 (2021)
(7) S. Rinner, F. Burger & A. Gritsch et al., Nanophotonics, 12 (2023)

Speaker: Karolina Weber (Max-Planck-Institut für Quantenoptik, Technische Universität München)

Scientific Session II (Invited talk Silke Bühler-Paschen)

Convener: Hannah Akhtar (RPTU)

15 How quantum are strongly correlated electron systems?

Silke Paschen
Institute of Solid State Physics, Technische Universität Wien

Strongly correlated electron systems host some of the most intriguing phenomena in condensed matter
physics, from unconventional superconductivity to quantum criticality and strange metallicity. But how
quantum are they, really? I will discuss how quantum information concepts, in particular the quantum
Fisher information, provide a way to quantify the quantumness of real materials. Focusing on the
strange metal state in heavy fermion compounds—where the conventional description in terms of
quasiparticles breaks down—I will show how this tool reveals high multipartite entanglement and
discuss possible implications.

Speaker: Silke Buehler-Paschen

16 Self-organized topological superfluid and sensing in a higher-band atom-cavity system

We propose to combine Bose-Einstein condensation in higher Bloch bands and a driven-dissipative cavity-BEC system into a hybrid light-matter platform. Specifically, the condensate is trapped in a bipartite $s$–$p_x$–$p_y$ lattice, with a tunable energy offset. This enables a controlled population transfer from the $s$-orbital to the nearly degenerate $p_x$ and $p_y$ orbitals. The system forms a chiral ground state with $p_x \pm i p_y$ symmetry, with staggered orbital currents. By increasing the transverse pump strength, we drive the system into the superradiant phase, resulting in a self-organized, density checkerboard, which rectifies the staggered chiral order into a topological superfluid state.

The emitted cavity field provides continuous optical access and enables a nondestructive readout of the internal quantum state. This may provide a basis for cavity-based sensing schemes, including possible applications in rotational sensing.

Our results show that higher-band condensates coupled to a cavity provide a promising platform for engineering non-trivial orbital order and topological superfluid phases in quantum optical many-body systems.

Speaker: Hannah Kleine-Pollmann (Universität Hamburg)

17 Quantics Representation of Time-Dependent Observables After a Quench

Over the past 30 years, tensor network techniques have been established as powerful tools in computational condensed matter physics. In one-dimensional quantum systems, one usually represents the many-body wave function as a matrix product state (MPS), a tensor network consisting of three-legged tensors, with individual tensors corresponding to the lattice sites in the system. This ansatz enables efficient numerical computations such as ground-state searches and time evolutions.
More recently, the concept of quantics tensor trains emerged, presenting a different perspective on tensor networks that serve as a way to represent (multivariate) continuous functions as tensor trains (cf. Núñez Fernández et al.). Instead of associating tensors with physical lattice sites, tensors encode scales that refine the domain of a function. This perspective has inspired many applications outside of quantum many-body physics, like superfast Fourier transforms.
We study how to effectively utilize the quantics framework to better understand quantum many-body dynamics of time-dependent observables after a quench. As an example, we will discuss the application of quantics tensor cross-interpolation to the quantum Ising model. We examine whether different parameters of the quantics representation or relating physical quantities allow us to reproduce information about the physical system. We find that low-index Rényi entropies exhibit qualitatively different behavior in the integrable and non-integrable regimes of the quantum Ising model, suggesting their potential as a tool for distinguishing between dynamical regimes.

Speaker: Alina Scheuermann (Max Planck Institute of Quantum Optics)

18 Polarization entanglement distribution over an actively stabilized 28 km urban fiber link

Entangled photon pair sources are essential resources for quantum technological applications. AlGaAs Bragg reflection waveguides are promising platform for such sources due to their high nonlinear coefficient, room temperature operation, and non-birefringent nature [1]. By using a type-II SPDC process, the down-converted photons are orthogonally polarized, and the generated photon pairs are inherently polarization entangled. Here, we present the generation and distribution of polarization-entangled photons over a 28 km dark fiber link. The link consists of commercial fiber, deployed both underground and overhead, includes several patching points, resulting in a transmission loss of $\approx$ 19 dB. The source produces a state with 95.7 $\%$ fidelity and 92.4 $\%$ purity w.r.t. the $|\psi^{+}>$ Bell state. After transmission over the actively stabilized [2] fiber link, the fidelity reduces to 87.9 $\%$ due to residual uncompensated polarization rotation whereas the purity remains unchanged (92 $\%$). In summary, we demonstrate a room-temperature entangled photon pair source at telecom wavelength, suitable for real world quantum applications. [1] F. Appas et al., J. Light. Technol. 40 (2022). [2] S. Kucera et al., npj Quantum Inf. 10, 88 (2024).

Speaker: Akriti Raj (University of Saarland)

19 Unveiling Topological Surface States through Planar Hall Signatures in exfoliated ZrTe₅ flakes

We report on the electronic and topological properties of ZrTe₅ flakes synthesized via chemical vapor transport (CVT). Mechanically exfoliated ZrTe₅ flakes with nominal thicknesses ~100 nm are transferred onto pre-fabricated Pt contacts with 1-3-3-1 Hall bar geometries on SiO₂/Si sugbstrates. Using ac phase-locked low-/high-magnetotransport measurements, a distinct longitudinal resistance peak at 150 K is observed, signaling a Lifshitz transition and a subsequent crossover from hole- to electron-dominated charge carrier transport. Analysis of Shubnikov-de Haas (SdH) oscillations and observation of an anomalous Hall effect yields a non-trivial Berry phase $(\phi_{B}=\pi)$, indicating the presence of topological surface states. Angle-resolved magnetotransport measurements reveal the emergence of a pronounced planar Hall effect around the transition temperature. These results characterize ZrTe₅ as a potential topological quantum material with applications in hybrid quantum devices such as topological Josephson junctions.

Speaker: Sophia Hollweger (Johannes Kepler Universität)

Postersession I

20 Experimental setup for trapping ultracold atoms near 4K solid state samples

Rydberg atoms are a promising platform for hybrid quantum systems due to their dipole-allowed transitions spanning frequencies from the optical to the microwave regime and their strong coupling to electric fields. To investigate their integration with solid-state devices, we are developing a cryogenic experimental platform combining ultracold rubidium atoms with an electromechanical resonator on an atom chip.

This poster presents our two-chamber experimental setup. In the first chamber the rubidium atoms are prepared in a magneto-optical trap and afterwards magnetically transported to a cryogenic second chamber. In this chamber, our solid-state atom chip can be inserted. On the chip, the cooled rubidium atoms can be trapped in close distance to the resonator via a magnetic trap realized by superconducting wires on the chip. The atoms can then be excited to high-lying Rydberg states, which couple to the modes of the resonator.

The cryogenic environment in the second chamber allows to quickly recover the ultra-high vacuum in the chamber after exchanging the chip, which lets us efficiently test and optimize different chip designs. To realize this unusually regular retrieval and reinsertion of the chip, we mount the room temperature part of the vacuum system on rails. This allows us to move the 25+ kg setup on the optical table with high precision.

We present the design and current status of the system to establish a flexible experimental platform for future hybrid atom–solid-state experiments.

Speaker: Theresa Dewey

21 Top-Hat Beam Shaping for Localized Laser Ablation Towards High-Resolution 3D Analysis of White Etching Cracks

White Etching Cracks (WEC) are complex crack networks that cause premature damage under rolling contact fatigue. Hydrogen is suspected of promoting crack formation, but its exact role remains unclear. Crack initiation and propagation are still insufficiently understood because of the interaction between microstructure, inclusions, and crack evolution.

A major challenge is that conventional microscopy provides only two-dimensional cross-sections, while WEC form intricate three-dimensional structures in the material. Three-dimensional characterization is needed to link macroscopic damage features, such as fisheye structures, with local crack initiation mechanisms.

In this work, an ultra-short pulse (USP) laser-based serial sectioning strategy is investigated for multiscale reconstruction of WEC-related damage structures. Due to the ultrashort interaction time, USP laser ablation enables rapid material removal with minimal thermal influence and reduced risk of preparation-induced artifacts. Large-area ablation followed by layer-wise optical imaging provides a fast method for three-dimensional mapping of fisheye structures and crack propagation paths.
To extend this approach to localized high-resolution analysis, a Top-Hat beam-shaping strategy is developed using a spatial light modulator.

Unlike a conventional Gaussian beam, the Top-Hat profile provides a more uniform energy distribution, enabling flatter and more reproducible material removal. The beam profile is characterized, and ablation thresholds are determined on steel to establish controlled micro-sectioning.

The results demonstrate the potential of tailored USP laser ablation and beam shaping for reproducible material removal across multiple length scales. The approach enables future correlative 3D analysis combining serial laser sectioning with electron microscopy, helping clarify the spatial relationship between crack morphology, microstructural features, and WEC initiation mechanisms.

Speaker: Pardis Saremi (IFOS GmbH)

22 Equity in the optics and photonics workplace

Since 2015, the Gender Equity Task Force of the international society for optics and photonics (SPIE) has been working to identify how the professional environment and culture of the optics and photonics community can better enable equal opportunities, rewards, and recognition for its members, independent of gender. The Task Force focuses on identifying and recommending specific steps our community can take to improve ongoing advocacy and career assistance for women and attract more women to pursue optics and photonics careers. Its 2017 report "Equity in the optics and photonics workplace" uses qualitative and quantitative data to explore various gender equity themes, including compensation, promotion, leadership, work/life balance, mid-career interruptions, and parenting. This poster highlights the report’s key findings.

Speaker: Ulrike Boehm (DPG Arbeitskreis Changengleichheit)

23 Two-tone control of a magnon Bose-Einstein condensate

In this work, we explore how a magnon Bose–Einstein condensate (BEC) responds to external perturbations and how its stability and lifetime can be controlled. The magnon BEC is created by populating the magnon gas above the thermal equilibrium level using pulsed parallel parametric pumping. A second pulse at a different frequency—with its parametric excitation frequency tuned from below the spectral minimum to above the ferromagnetic resonance frequency—is then applied to the already formed condensate. This additional pulse enables a controlled perturbation of the non-equilibrium spin system and, thereby, engineering of the magnon excitation and the thermalization process. The condensate dynamics are studied using frequency-, time-, and wavevector-resolved Brillouin light scattering spectroscopy. This research was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)-TRR 173/3-268565370 Spin+X (Project B04 and B13).

Speaker: Franziska Kühn (RPTU Kaiserslautern)

24 Temporal Invariance Is an Illusion: Time-Dependent Influences of the Galactic Magnetic Field on UHECR Observations

Understanding the origin of the Ultra-High-Energy Cosmic Rays (UHECRs) requires explaining the features of their energy spectrum, mass composition, and arrival directions. Current modeling approaches neglect the time evolution of UHECR observables, a factor that is particularly important in the case of bursting UHECR sources. This study focuses on the influence of time delays caused by the galactic magnetic field (GMF) on the spectrum and arrival directions of UHECRs observed on Earth. Using CRPropa 3.2, we investigate the rigidity-dependence of the residence time of extragalactic cosmic rays entering our Galaxy. We find that UHECRs entering the Milky Way can experience delays of hundreds of kiloyears relative to light, and we demonstrate that these delays significantly alter the UHECR observables. Notably, a cutoff emerges in the transient scenario within the rigidity range of $10^{18}-10^{19}~$V, which coincides with the spectral break observed in data. We find a progressive shift in composition favoring heavier nuclei, as well as a delay distribution that is correlated with GMF strength.
This causes the particles to be less correlated with their initial direction the larger their delays.
A dipole-like anisotropy develops over timescales of about $\sim$100 kyr in certain bursts scenarios. Our results provide an alternative explanation for the UHECR spectral cutoff that does not invoke limits on source acceleration. This could potentially revise existing constraints.

Speaker: Veronika Vašíčková (BUW)

25 Exploration of Iron(III) in Phosphate recovery from Wastewater using Nuclear Inelastic Scattering

The recovery of phosphate from wastewater is essential for a healthy aquatic ecosystem. One of the most commonly used methods for recovering phosphate from wastewater is chemical precipitation. In this process Fe(III) reacts with phosphate to form ferric phosphate that settles as Fe-P particles. However, the molecular mechanisms that govern iron-phosphate interactions under different chemical conditions are not well understood. In this study, nuclear inelastic scattering experiments were conducted to identify iron species via their the vibrational properties. We used Nuclear Inelastic Scattering (NIS) of 57Fe enriched iron(III) solutions at pH 1, 2, 7, and 11. NIS data of iron(III)-phosphate solutions were also measured under the same pH conditions, with phosphate solutions serving as a model wastewater systems. Comparative analyses between iron(III) and iron(III)-phosphate solutions were performed to investigate the influence of phosphate on the coordination environment and vibrational characteristics of the iron species.
Quantum chemical density functional theory (DFT) calculations were performed with the aim to relate vibrational bands observed in the NIS experiments to molecular structures of iron species formed. In water solutions at very low pH values, iron is generally present predominantly as monomeric species. However, as the pH approaches around 2, the formation of small polymeric species becomes more feasible, like heptameric or Keggin-type iron clusters. Neutral (pH~7) and basic (pH~11) solution promote the formation of large polymeric iron oxo species.

Speaker: Hannah Akhtar (RPTU)

26 A hybrid lattice–tweezer platform for quantum simulation and computation with strontium atoms

Neutral-atom platforms offer a promising route toward scalable quantum simulation and computation, but combining large system sizes with precise local control remains a central challenge. We address this using a hybrid platform that combines a large optical lattice with individually controlled optical tweezers. In strontium-88, the lattice provides more than 10,000 trapping sites and supports high-fidelity imaging, while static and movable tweezers enable local control and atom rearrangement. This architecture balances scalability and addressability and allows continuous loading and iterative assembly of large, low-defect atom arrays without interrupting operation.

These continuously replenished arrays provide the scalable atomic register for our quantum-computing experiments. For computation, we encode each qubit in two long-lived metastable states of strontium, forming a fine-structure qubit that combines long coherence with access to Rydberg-mediated interactions. On this platform, high-fidelity single- and two-qubit operations establish a universal gate set, complemented by state-resolved detection of erasure errors. Atomic motion can also be used as a control resource: Doppler shifts distinguish moving from stationary atoms, enabling velocity-selective state preparation and readout, local phase gates, and entangling operations on the fly. Spatial light modulators and digital micromirror devices provide a route toward parallel single-site addressing.

Beyond quantum computation, the same platform is well suited to analog quantum simulation of interacting many-body systems, including Rydberg spin models, Hubbard physics, and lattice gauge theories. Future directions also include collective light–matter phenomena such as superradiance on the ³P₂–³D₃ transition.

Speaker: Taylor Briggs

27 A Modular Wiring and Filtering Architecture for the Bluefors Fast Sample Exchange

The investigation of superconducting Josephson junctions requires low-noise and configurable DC measurement setups capable of resolving superconducting features. To improve the experimental capabilities of a Bluefors® dilution refrigerator, a modular upgrade of the Fast Sample Exchange (FSE) puck was developed, focusing on flexible wiring, integrated filtering, and improved sample handling.
The puck incorporates a modular printed circuit board (PCB) architecture enabling the integration of different wiring configurations. A dedicated grounding PCB provides electrostatic discharge (ESD) protection during sample installation. Additional adapter PCBs enable the replacement of conventional wiring with up to 24 Thermocoax lines. Owing to their distributed attenuation and continuous thermalization, Thermocoax cables have been proposed for suppressing high-frequency noise while maintaining low thermal load [1]. Optional per-channel RC low-pass filters further extend the available filtering configurations according to the requirements of individual experiments.
The PCB designs are currently under fabrication, and experimental characterization remains future work. This modular approach aims to establish a configurable wiring infrastructure for fast-paced implementation and low-noise DC measurements of superconducting devices, including Josephson junctions.

[1] C. P. Scheller, S. Heizmann, K. Bedner, D. Giss, M. Meschke, D. M. Zumbühl, J. D. Zimmerman and A. C. Gossard, “Silver-epoxy microwave filters and thermalizers for millikelvin experiments,” Appl. Phys. Lett. 104, 211106, vol. 104, no. 21, 2014.

Speaker: Lotta Ehlert (JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University)

28 Application of Raman spectroscopy in the context of MgO-C refractory recycling and upcycling

In the face of 28 million tonnes of spent refractories annually, recycling and upcycling strategies for MgO-C refractories are crucial to more sustainable and environmentally friendly materials management in high-temperature industries. The research training group GRK 2802 funded by the German Research Foundation (DFG) investigates two core ideas addressing the use of spent MgO-C.
The recycling idea aims to combine spent MgO-C with fresh fused MgO, graphite, and a novel environmental friendly binder system replacing the carcinogenic and hazardous conventional binders. In our project, Raman spectroscopy is applied to characterize the carbon structures in the novel binders and their transformation during pyrolysis at temperatures up to 1000°C. Raman spectroscopy allows for assessing the ratio between sp2- and sp3-hybridized carbon, the hydrogen content and the average sp2 carbon cluster size evaluating the binder performance.
The upcycling idea intends to develop a low/no carbon anode material for aluminum production. Substituting graphite electrodes by an MgO-steel composite would reduce the CO2 emission of the fused-salt electrolysis. During a pre-oxidation step in the production of the MgO-steel composite, different spinel phases are formed improving the corrosion resistance of the anode. As Raman spectroscopy is sensitive to cation disorder in spinel systems, it is employed to identify phases - right now in model spinel systems and in the future also in fresh and used MgO-steel anodes.
Finally, the application of the laser excitation to MgO-C itself reveals defect-related photoluminescence (PL) bands with phonon sidebands. The poster gives an overview on all three aforementioned use cases highlighting the potential of Raman and PL spectroscopy in refractory material science.

Speaker: Julia Richter (TU Bergakademie Freiberg)

29 Beyond Topography: Multimodal AFM for Biological Interfaces

Atomic Force Microscopy (AFM) is a versatile tool for studying biological systems from the single cell to the nanoscale. By combining tailored surface functionalization, single-cell force spectroscopy, FluidFM-based cell manipulation, and correlative AFM–confocal microscopy, we establish an experimental framework to investigate biological interfaces and microbial adhesion.

Silicon substrates with well-defined surface properties were prepared using octadecyltrichlorosilane (OTS) coatings [1,2,3], hydrophobin (HFBI) protein layers [1], or etching protocols that introduced nanoscale roughness [4]. These model surfaces facilitate a systematic investigation of how surface chemistry and topography govern interfacial structure, stability, and cell adhesion.

Single-cell force spectroscopy quantified the adhesion of individual Staphylococcus aureus and Shewanella oneidensis cells immobilized by either polydopamine or vacuum-based FluidFM probes. Force–distance measurements revealed species-specific and surface-dependent adhesion signatures [2,3,4], thus highlighting the importance of hydrophobicity [4] and nanoscale roughness [5] in microbial interactions.

Correlative AFM–confocal microscopy complements these measurements by linking mechanical, structural, and biochemical information. Applied to bacterial cell walls, extracellular vesicles, and hydrogel-embedded capsules, this multimodal approach provides a comprehensive view of biological interfaces and demonstrates how combining complementary techniques can reveal structure–function relationships that remain inaccessible to individual methods alone.

References:
[1] Wieland, B.; et al.: ACS Omega (2025) 10, 34, 38376–38384.
[2] Klein, E.; et al.: Scientific reports 14 (2024) 23174.
[3] Klein, E.; et al.: New BIOTECHNOLOGY 89 (2025).
[4] Spengler, C.; et al.: Nanoscale 11 (2019) 19713.
[5] Spengler, C.; et al.: Nanoscale 9 (2017) 10084.

Speaker: Hannah Heintz (Saarland University)

30 Depth- and orientation-resolved analysis of lithium penetration and interface chemistry in single-crystal silicon anodes

Silicon is a promising lithium-ion anode material, storing about ten times more lithium than graphite, but its large volume change and unstable solid-electrolyte interphase (SEI) limit the lifetime and quality of the cell. Whether the crystal lattice or the native-oxide/SEI surface layer governs how deep lithium penetrates remains unsolved, as the two contributions are difficult to separate in polycrystalline or nanostructured electrodes.
This study uses single-crystal Si(100), Si(110) and Si(111) wafers as a model system with one defined surface and one defined oxide, cycled against lithium in liquid-electrolyte coin cells. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) serves as the central method, complemented by X-ray photoelectron spectroscopy (XPS), X-ray reflectometry (XRR), white-light interferometry and focused ion beam (FIB) cross-sections.
On the pristine wafers, XPS resolves an orientation-dependent oxide, with Si(110) being the most oxidic. On cycled Si cells of different orientations, depth-calibrated ToF-SIMS profiles distinguish lithium penetration depths and FIB cross-sections provide an independent thickness of the modified layer. Raman spectroscopy and transmission electron microscopy/electron energy-loss spectroscopy (TEM/EELS) are planned to add the crystalline-to-amorphous transition and the local LixSi phase that ToF-SIMS cannot resolve. This work establishes the depth-resolved analytical chain required to disentangle lattice- and surface-controlled lithiation.

Speaker: Hariklea Athanasiou

31 In-situ nanodiamond-based quantum sensing of free radicals in photocatalytic reactions

Nanodiamonds with crystal defects have gained increasing importance in biological and chemical applications [1]. Most prominent are fluorescent nanodiamonds (FNDs) with nitrogen-vacancy (NV) centers due to their unique properties such as high photostability, chemical inertness and sensitivity towards magnetic and electric fields [2,3]. These properties make them highly suitable for the in-situ detection of paramagnetic species, such as free radicals, in chemical reactions [1,3,4]. This detection is enabled by NV center-based, microwave-free T1 relaxometry measurements, which are sensitive to magnetic fluctuations [1,4].
These FNDs with NV centers and their properties can be utilised in the increasingly important field of photocatalytic chemistry. Photocatalysis is emerging as a key option in the ongoing energy transition from fossil fuels towards more sustainable energy sources [3]. However, the material composition, efficiency and possible intermediates are not yet sufficiently well understood to enable photocatalysis to be implemented on a large scale in practical applications [3]. With the use of FNDs with NV centres for in-situ analysis of paramagnetic intermediates it is intended to gain a more profound understanding of photocatalytic reactions.
In this study, the photocatalytic reaction between cadmium selenide/cadmium sulfide nanorods (CdSe/CdS NR) with methyl viologen (MV) was investigated by means of NV center-based T1 relaxometry measurements.

References
[1] R. Schirhagl, ACS Sensors 5, 3862 (2020)
[2] C. L. Degen, Annu. Rev. Phys. Chem. 65, 83 (2014)
[3] A. E. Lanterna, Adv. Func. Mat., e76935 (2026)
[4] D. A. Simpson, Phys. Rev. Applied 20, 034018 (2023)

Speaker: Helena Gutheil (RPTU in Kaiserslautern)

32 Integration of Quantum Dots and Nonlinear Organic Materials into 3D- Printed Microstructures

Functional materials embedded in three-dimensional photonic microstructures offer new routes for advanced photonic devices. We present two different approaches towards such devices: the incorporation of colloidal quantum dots (QDs) into 3D-printed microstructures for hyperspectral sensing applications, and the integration of the nonlinear organic molecule DDMEBT into 3D microstructures to realize all-optical functionalities.

Quantum dots with size-dependent electronic properties are attractive as wavelength-selective optical materials for sensing applications. One key application benefiting from the spectral selectivity is hyperspectral imaging, where a complete optical spectrum is acquired for each image pixel, enabling the identification of materials in fields ranging from environmental monitoring to forensic analysis.
However, current systems rely on bulky dispersive optics with limited quantum efficiency and poor performance at low light levels. This restricts measurements on weakly illuminated or strongly absorbing samples and hampers integration into compact devices. To address these limitations, this project integrates size-tuned QDs into 3D-printed photonic waveguide structures, where stacked QD layers provide wavelength-resolved detection without large optical components.
In this contribution, suitable photoresists and polymer host materials are screened regarding QD compatibility and spectroscopic functionality as prerequisites for efficient waveguide infiltration.
In a complementary approach, DDMEBT is investigated in photoresist and polymer composite systems. Combining strong optical Kerr nonlinearity with a comparatively high refractive index, it offers potential for all-optical signal processing and switching. Here, the compatibility with different host materials and the resulting nonlinear optical properties are studied as a first step towards 3D-printed microstructures for integrated nonlinear photonic devices.

Speaker: Emily Kruel (RPTU Kaiserslautern-Landau)

33 Momentum-Resolved Excited-State Dynamics on ZnO Surfaces

ZnO is a prototypical wide-band-gap material with long-lived excitons, making it a central platform for modern optoelectronic and catalytic technologies, especially for investigating exciton-related phenomena [1]. Excitons—bound electron–hole pairs that can exist in various forms near the surface, significantly shape the material’s optical and electronic response and play an essential role in interfacial energy-conversion processes [2]. However, studies that directly characterize these excitons, particularly if they are defect-mediated, localized or mobile, or predominantly Frenkel- or Wannier-type, remain limited.

Here we address these questions using time-resolved momentum microscopy to map the fingerprints of excited states in energy, momentum and time [3]. We present first experimental momentum-space maps of the ZnO(10-10) surface exciton states and track their real-time evolution following photoexcitation. We observe clear signatures of surface exciton formation, including their emergence in the unoccupied band structure and their subsequent relaxation dynamics on ultrafast timescales.

Speaker: Hashima Marukara (University of Goettingen)

34 NV-center based thermometry for applications in microfluidic devices

Nitrogen-vacancy (NV) centers in diamond are an attractive platform for quantum sensing because they exhibit stable optical and spin properties at room temperature [1, 2]. An NV center consists of a nitrogen atom substituting a carbon atom and a neighbouring vacancy in the diamond lattice [2]. Owing to their environmental sensitivity, high spatial resolution, and excellent biocompatibility, NV centers are promising for high-resolution temperature sensing, particularly where conventional infrared thermography cannot be applied [1–4].

This work employs all-optical thermometry based on temperature-dependent shifts of the optical zero-phonon line (ZPL) [5, 6]. All-optical thermometry using NV centers in single-crystal diamond is investigated from approximately 20 °C to 55 °C. The samples are first characterised by confocal microscopy, followed by temperature-dependent measurements in a flow-cell system that simulates future application conditions. Fluorescence spectra are analysed in terms of ZPL position and amplitude, and their spatial variation is used to investigate temperature gradients within the diamond. This provides the basis for future applications in which the temperature of flowing water may be inferred from the measured temperature distribution. First results demonstrate the potential of all-optical NV thermometry for spatially resolved temperature measurements and the investigation of local thermal processes.

[1] M. W. Doherty et al., Physics Reports, vol. 528, no. 1, 2013.
[2] R. Schirhagl et al., Annual Review of Physical Chemistry, 2014, doi: 10.1146/annurev-physchem-040513-103659.
[3] P. G. Kucsko et al., Nature, vol. 500, pp. 54–58, 2013, doi: 10.1038/nature12373.
[4] P. Neumann et al., Nano Letters, vol. 13, no. 6, pp. 2738–2742, 2013, doi: 10.1021/nl401216y.
[5] M. Fujiwara and Y. Shikano, Nanotechnology, 2021, doi: 10.1088/1361-6528/ac1fb1.
[6] M. Li et al., Advanced Quantum Technologies, vol. 7, no. 3, 2024, doi: 10.1002/qute.202300293.

Speaker: Hannah Günster

35 Optical Characterizations on the Effect of Surface Terminations on Shallowly Implanted Tin-Vacancy Centers in Diamond.

Group-IV color centers in diamond are well known for their suitability as nodes within quantum networks due to their excellent spin and optical coherence. The tin-vacancy center (SnV-) in particular shows Fourier limited linewidths, a small inhomogeneous distribution of emission wavelengths, and excellent long-term spectral stability [1-3]. The latter two of which have been observed for deep implanted emitters, after high pressure high temperature (HPHT) annealing to reduce lattice damage.
However, these SnV-'s in bulk diamond are limited to a collection efficiency of only a few percent [4], insufficient for most applications. This may be improved through redirection of light towards collection optics. Further enhancement of the collected photon count rate can be obtained through Purcell enhancement in nanophotonic structures such as circular Bragg gratings. In these structures SnV- centers are always close to the diamond surface. However, HPHT annealing is damaging to the diamond surface, and so to benefit from these enhancements other ways of stabilizing emitters must be explored.
Here we present a statistical analysis of room temperature measurements on the effect of surface terminations on shallow (20 - 100 nm implantation depth) SnV- centers annealed under vacuum at 1200°C. A thermally oxidised sample, a hydrogen and hydroxyl group terminated sample are compared to a tri-acid cleaned sample. It is seen that compared to the tri-acid sample, the remaining all show improvements in charge state stability and reductions to background fluorescence, with the long term stability of both hydrogen and hydroxyl group terminations surpassing that of the thermal annealing. We intend to measure these samples also at < 2 K.
[1] M. Trusheim, et al., Phys. Rev. Lett. 124(2) (2020), 023602, [2] J. Görlitz, et al., npj Quantum Inf 8(1) (2022), 45, [3] Y. Narita, et al., Phys. Rev. Applied 19(2) (2023), 024061, [4] E. Janitz, et al., Optica 7(10) (2020), 1232-1252.

Speaker: Gabrielle Hunter-Smith (Universität des Saarlandes, Fachrichtung Physik)

36 Quantum-Based Pressure Metrology utilizing a Fabry–Perot Refractometer

Quantum-based approaches are emerging as a promising alternative for high-accuracy pressure metrology, offering direct SI traceability and the potential to reduce measurement uncertainties. This work presents the development and improvement of a Fabry–Perot refractometer as part of ongoing efforts to realize quantum-based pressure standards. The system was designed, assembled, and used to perform pressure measurements based on refractivity determinations at the National Metrology Institute of Germany “Physikalisch-Technische Bundesanstalt” (PTB). Its performance was evaluated through comparisons with conventional pressure standards, providing an initial assessment of its measurement capabilities and consistency with established methods. The poster presents the current status of the refractometer, highlights initial measurement results, and outlines ongoing efforts to further improve its performance. The presented work contributes to ongoing developments within the recently launched “25IEM03 EQB-Pascal” project within the European Partnership on Metrology (EPM) program.

Speaker: Sara Gehauf (Physikalisch-Technische Bundesanstalt)

37 Qudit-Based Quantum Error Correction with High-Spin Nuclei

High-spin nuclei have emerged as a promising resource for quantum computing, owing to their large, high-dimensional state spaces and the maturity of the solid-state hosts in which they reside. Because each nucleus behaves as a qudit rather than a two-level qubit, its extra dimensions can be used to encode and protect quantum information, opening new routes to quantum error correction.

Exploiting these dimensions at scale, however, remains challenging, since it also demands the ability to entangle individual nuclei and link them across a device. In our work, we study germanium-73 nuclei in silicon, a CMOS-compatible host in which each nucleus is a ten-level qudit. We investigate entanglement schemes in which an electron mediates the interaction between nuclei, using electron shuttling to establish entanglement over extended distances, and we model the realistic errors that arise during these processes.

With this approach, we aim to develop a building block for scalable, fault-tolerant quantum computing based on these high-dimensional nuclei.

Speaker: Sarah Elizabeth Budai

38 Spectroscopy of Tin-Vacancy color centers in a solid immersion lens

The negatively charged Tin-Vacancy (SnV$^-$) color center in diamond is a promising candidate for solid-state quantum network nodes due to its long spin coherence times and fourier limited optical transitions.
Diamond, as a host material, has a large refractive index of $n=2.4$ which limits the amount of light that can escape past its boundary surface caused by total internal reflection. This restricts the collection efficiency of a single SnV$^-$ color center.
Several approaches have been proposed to increase the detected photon rate, either by enhancing spontaneous emission through the Purcell effect or improving photon outcoupling and collection efficiency.
This work employs a hemispherical solid immersion lens (SIL) made out of diamond with a diameter of 1 mm. Such a geometry remedies the issue of total internal reflection and therefore promises a higher outcoupling rate.
We observe a fivefold increase compared to bulk-like countrates measured on the flat surface. This enhancement in photon collection therefore contributes to the development of efficient quantum network nodes.

Speaker: Julie Kolling

39 Structure and dynamics of the Fe-S-cluster of human Primase II

Without DNA replication human life would not be possible because cells would be unable to divide and renew themselves [1]. The enzyme responsible for DNA replication, DNA polymerase, cannot synthesize new DNA de novo from the DNA template [2]. It requires a primer, which is produced by primase [3]. The primary sequence of human primase II contains a binding motive for a [4Fe4S] cluster which has not yet been studied in detail. Therefore, we have used Mössbauer spectroscopy and synchrotron based nuclear forward scattering (NFS) to investigate the electronic properties of the [4Fe4S] cluster. In addition, we have explored the protein with synchrotron based nuclear inelastic scattering (NIS) and accompanying density functional theory (DFT) calculations together with vibrational mode analysis with the aim to identify cluster vibrations which might support an electron transfer function of the cluster.

References
[1] Jens Boenigk, "Boenigk Biologie": Der Begleiter in und durch das Studium, Springer Spektrum, Springer-Verlag GmbH, DE, Heidelberg, 2021, ISBN: 978-3-662-61269-9.
[2] B. Arezi, R.D. Kuchta, "Eukaryotic DNA primase", Trends in Biochemical Sciences 25 (2000) 572–576.
[3] B.E. Weiner, H. Huang, B.M. Dattilo, M.J. Nilges, E. Fanning, W.J. Chazin, "An iron-sulfur cluster in the C-terminal domain of the p58 subunit of human DNA primase", Journal of Biological Chemistry 282 (2007) 33444–33451.

Speaker: Vivien Christl

40 Synchrotron-based Mössbauer spectroscopy and density functional theory calculations of iridium(I) complexes with and without multimetallic bonding to fullerene

Iridium complexes have highly interesting photochemical, photophysical and catalytic properties. They are used for example in organic light-emitting diodes (OLEDs), organic solar cells and automotive exhaust catalysts.[1,2,3] Iridium complexes have also been used to initiate "water oxidation reactions“.[4,5] They also hold promise as photosensitisers and photocatalysts for directed photodynamic cancer therapy (PDT).[3,6] Recently nuclear forward scattering (NFS) on $^{193}$Ir at 73 keV has been established at beamline P01, PETRA III, DESY, Hamburg.[7] This technique can be regarded as Mössbauer spectroscopy in the time domain. We have applied $^{193}$Ir-NFS to yield information about the electronic properties of selected catalytically active Iridium complexes via the determination of Mössbauer parameters like isomer shift and quadrupole splitting . We have also performed Density Functional Theory (DFT) calculations to calculate the Mössbauer parameters of the complexes under investigation [8,9].

References
[1] Yang, C.-H., et al. Angew. Chem. 2007, 46(14), 2418-2421
[2] Dragonetti, C., et al. Inorg. Chim. Acta 2012, 388, 163
[3] M.L.P.Reddy, K.S.Bejoymohandas, J. Photochem. Photobiol. C: Photochem. Rev. 2016, 29, 29-47
[4] McDaniel, N.D., et al. J. Am. Chem. Soc. 2008, 130(1), 210-217
[5] Hull, J.F., et al. J. Am. Chem. Soc. 2009, 131(25), 8730-8731
[6] Day J. I. et al. Org. Process Res. Dev. 2016, 20(7), 1156-1163
[7] P.Alexejev et al., Sci. Rep. 2019, 9, 5097
[8] M.H.Hoock et al., Hyperfine Interact. 2023, 244, 24
[9] M.H.Hoock et al., Interact. 2026, 247, 51

Speaker: Maren Hoock (RPTU Kaiserslautern-Landau)

41 The Roving Laser System for Absolute Energy Calibration of the Fluorescence Telescopes at the Pierre Auger Observatory

The Fluorescence Detector (FD) of the Pierre Auger Observatory provides energy measurements of primary cosmic rays that are largely independent of specific interaction models. These measurements are crucial for calibrating the energy reconstruction of the Surface Detector. Consequently, the accuracy of the FD energy calibration plays a key role in the systematic uncertainties associated with nearly all scientific results of the Observatory.
To this end, a laser with a well-defined pulse energy will be fired into the field of view of the FD telescopes. Unlike other calibration methods, the response of the telescopes to the laser closely simulates the response to an actual cosmic-ray air shower. The system was designed with special attention to the depolarization of the laser beam to ensure a consistent relationship between laser energy and directional light yield.
This contribution presents results from laboratory measurements of the laser system, which were performed to validate and optimize its performance before field deployment. In addition, we present results from the first in-field tests of the system at the Pierre Auger Observatory in Argentina.

Speaker: Rukije Uzeiroska-Geyik (Deutsch)

42 „Mehr (für) Physik-Studentinnen*" – Networking, Enabling, Spotlighting: A pioneering subject-specific project on gender equality in physics

Physics continues to be regarded as a male-dominated subject with a ‘leaky pipeline’ throughout the career progression – from the beginning of undergraduate studies right through to a professorship. Since 2021, the "Mehr für Physikstudentinnen" ("More (for) Female Physics Students") project at the Department of Physics and the Gender Equality Office at Marburg University has been addressing this issue: not through an overarching gender equality programme, but through subject-specific, low-threshold initiatives – funded by the Professorinnenprogramm 2030.
The project is based on three pillars: networking through informal activities such as ‘Women Physicists’ breakfasts, group climbing, barbecues and boat trips, and the joint development of exercise sheets or protocols; Enabling opportunities through themed excursions to research institutions such as ESA, GSI and DESY, participation in conferences, supplemented by ad hoc financial support; and Spotlighting through an annual alumna presentation and a continuous presence within the department.
To the best of our knowledge, ‘Mehr für Physikstudentinnen’ is therefore a pioneering project: to our knowledge, no other university has a comparable structure permanently embedded within a department. In its equality strategy (Gleichstellungskonzept für Parität), Marburg University has made a conscious decision not to pool resources exclusively at central level, but to invest specifically in department-specific equality work.
The poster presents the concept, formats and initial success factors, and invites discussion on the potential for transferring this model to other departments and campuses.

Speaker: Stefanie Wittich (Marburg University)

43 Detailed balance and effective temperatures in a dissipative Spin-Boson model via rate equations

Larissa Schwarz1 and Simon B. Jäger2
1University of Kaiserslautern-Landau
2University of Bonn

Abstract

We derive an effective semiclassical rate-equation description of the collective spin dynamics of
the dissipative Dicke model in the strong spin–cavity coupling regime. Using a polaron trans-
formation and the Nakajima–Zwanzig projection method, we obtain a Pauli master equation
for the populations of the spin eigenstates, with transitions restricted to nearest neighbors. We
solve the corresponding detailed-balance steady state and, by accounting for the degeneracy of
the collective spin states, recover the superradiant phase transition of the Dicke model.
Additionally, we show that the resulting detailed-balance steady state can be expressed in a
quasi-thermal Gibbs form with a state-dependent effective temperature. In the large spin num-
ber limit, we map the rate equation onto a Fokker–Planck equation, whose stationary solution
provides an analytical solution of the steady state.

Speaker: Larissa Schwarz

44 Entanglement detection from syndrome data

Quantum error correction protects fragile quantum information by encoding it non-locally across many physical qubits, and stabilizer measurements, the syndromes used to diagnose errors, are performed continuously on any error-corrected device. In this work we ask what this routinely collected data certifies about entanglement, at no additional measurement cost. Focusing on the seven-qubit Steane code, we show that the syndrome statistics of the six stabilizer generators alone certify that the codespace is both a completely entangled subspace and a genuinely entangled subspace: every state supported on it, including arbitrary mixtures of codewords, is genuinely multipartite entangled. We construct several entanglement witnesses from syndrome data, characterise which states they detect, and quantify their noise tolerance under white and local depolarizing noise, finding that the ranking of the witnesses depends on the noise model. Adapting the witnesses to the measured syndrome extends entanglement certification to all 64 error sectors. Finally, we prove a fundamental limitation: for two encoded logical qubits, the syndrome is constant across the entire joint codespace and therefore provably blind to entanglement between logical qubits. Syndrome data thus certifies the physical entanglement that error correction relies on, while the logical information it protects remains, by design, invisible.

Speaker: Drashti Dhoriyani (University of Siegen)

45 Influence of Film Thickness on the Laser-Induced Switching Properties of the Phase Change Material Ge₂SeTe

Ge₂SeTe is a promising phase-change material (PCM) for programmable photonic integrated circuits (PICs) operating in the infrared spectral range. Since continuous tuning of such devices requires a detailed understanding of thickness-dependent switching behavior, thin films of 40, 80, and 160nm were investigated using a Phase-Change Optical Tester.
Under laser-induced crystallization, the thicker films require less energy to crystallize and exhibit faster crystallization than the thinner films, while the crystallization process itself showed inherently stochastic behavior. Similar thickness-dependent trends were observed during reamorphization and recrystallization.
Electron backscatter diffraction (EBSD) was used to further investigate the crystallization process and its stochasticity. The measurements indicate a low nucleation rate, while no clear dependence of the nucleation on film thickness was observed.

Speaker: Laura Gundermann (RWTH)

46 PHYSIKERINNEN: Zahlen und Fakten

Carola Meyer, Dagmar Paarmann, Agnes Sandner,
Beate Klösgen ( für die AKC-Kommission)

Der Arbeitskreis Chancengleichheit (AKC) wurde 1998 als ein Arbeitskreis
innerhalb der Deutschen Physikalischen Gesellschaft e.V. (DPG) gegründet.
Das Ziel des AKC ist die Verbesserung der Chancengleichheit für alle
Physiker:innen, beginnend auf allen Ebenen der DPG und im Sinne der
umfassenden Repräsentanz aller mit der Physik verbundenen Individuen. Der
AKC setzt sich für die allgemeine Akzeptanz von Diversität ein. Als größte
Minderheit in der DPG waren bisher Frauen und die Erhöhung der Sichtbarkeit
ihrer Beiträge in Wissenschaft und Entwicklung ein Schwerpunkt. Das Poster
weist die kontinuierliche Erhöhung des Frauenanteil in der Physik auf, zeigt
aber auch deutlich die weiterhin bestehende Ungleichverteilung bei
Preisverleihungen und in der Besetzung von Professuren.

Speaker: Beate Klösgen (University of Southern Denmark)

47 Zeno-Assisted Quantum Heat Engines

Selma Memić, Rafael Wagner, Susana F. Huelga, Martin B. Plenio
*Institut für Theoretische Physik, Universität Ulm, Ulm, Germany

Finite-time quantum heat engines suffer from quantum friction, generation of
coherences as the working fluid is driven – which, if not addressed, results in lowering the
efficiency of an engine1. Lubrication protocols address quantum friction by coupling an auxiliary
system (lubricant) which helps controlling and mitigating the coherences being generated2.
In this work, we construct a new form of lubrication using strong coupling between the
working system and the lubricant, and continuous monitoring of the lubricant, using the effect
known as quantum Zeno dynamics3.
We apply our idea to an Otto cycle, and show that in the
(perfect) Zeno limit our engine achieves the (quasistatic) Otto efficiency and non-zero power.
While idealized Zeno dynamics suggests that arbitrarily fast operation at optimal
efficiency is possible, its implementation incurs additional thermodynamic costs. These were
also investigated and proven not to limit practical usefulness of our findings, in specific regimes.
Finally, we showed that our protocol results in the same effective dynamics for the
working fluid as counter-diabatic driving5.
Our work showcases new applications of the Zeno
effect for the quantum control of nanoscale engines and motivates this as an interesting
platform for foundational work at the intersection of strongly interacting quantum
thermodynamics and quantum control.

References:
1 R. Kosloff and T. Feldmann, Discrete four-stroke quantum heat engine exploring the origin of
friction, Phys. Rev. E 65, 2002.
2 T. Feldmann and R. Kosloff, Quantum lubrication: Suppression of friction in a first-principles
four-stroke heat engine, Phys. Rev. E 73, 2006.
3 P. Facchi and S. Pascazio, Quantum Zeno dynamics: mathematical and physical aspects, J.
Phys. A: Math. Theor. 41, 2008.
4 D. Guéry-Odelin, A. Ruschhaupt, A. Kiely, E. Torrontegui, S. Martínez-Garaot, and J. G. Muga,
Shortcuts to adiabaticity: Concepts, methods, and applications, Rev. Mod. Phys. 91, 2019.

Speaker: Selma Memic (Institut für Theoretische Physik, Universität Ulm)

Tuesday 29 September

Registration

Sitzung des AKC

48 Informationsveranstaltung und Mitgliederversammlung des Arbeitskreis Chancengleichheit

Der Arbeitskreis Chancengleichheit (AKC) der DPG hält im Rahmen der DPT eine Informationsveranstaltung und seine jährliche Mitgliederversammlung ab. Alle Mitglieder sowie auch weitere Interessierte sind herzlich zur Teilnahme eingeladen!
Die AKC-Kommission berichtet über ihre Arbeit des vergangenen Jahres und gibt eine Vorschau auf geplante Projekte und Veranstaltungen. Alle Anwesenden sind aufgerufen, sich aktiv mit neuen Ideen und Vorschlägen einzubringen. Eure Mitarbeit an den einzelnen Projekten ist jederzeit willkommen.
Im Rahmen der Mitgliederversammlung wird zudem nach den Regularien des AKC die Wahl neuer Kommissionsmitglieder stattfinden.
Wir freuen uns auf Euch.

Speakers: Agnes Sandner, Dagmar Paarmann

Keynote II (Prof. Monika Ritsch-Marte)

Convener: Christina Jörg (RPTU University Kaiserslautern-Landau, Department of Physics and State Research Center OPTIMAS, Kaiserslautern, Germany)

49 Ultrasound-mediated Optical Tomography of Biomedical Samples

Organoids and cancer spheroids are often too opaque for optical imaging by single-sided illumination. Rotating the sample for multi-angle illumination solves this, enabling 3D tomographic reconstruction of the refractive index. Optical and acoustic forces can both manipulate microscopic samples in suspension without contact, but heavier samples require acoustic levitation. Tuning standing MHz ultrasound waves from various directions allows one to rotate a sample within a microfluidic chamber. The method is non-invasive and avoids the "missing-cone" artifact problem. Examples shown include 3D reconstructions of a levitated zebrafish larva via Optical Coherence Tomography (OCT) and of cell clusters via Optical Diffraction Tomography (ODT).

Speaker: Monika Ritsch-Marte (Medical University of Innsbruck)

10:15 Coffee Break

Physics@Work II

Convener: Sandra Wolff

50 From Research to Startup with LAHA – Laser Hearing Aids

After completing my degree in medical biophysics at RPTU Kaiserslautern, I joined LAHA – Laser Hearing Aids, a research transfer project with the goal of developing a laser-based hearing aid and founding a startup.
In my talk, I will share what it is like to work at the intersection of fundamental research and company building and how a biophysics degree prepares you for some of it – and leaves you to figure out the rest.
In my first year, I ran simulations and conducted lab experiments to prepare for our first-in-human study, a study in which we demonstrated that humans can indeed hear light, thanks to the optoacoustic effect. Following this milestone, I presented our results at scientific conferences and co-authored a publication.
In my second year, securing funding became the priority. I joined the investor-finding team, gained hands-on experience in startup financing, and began pitching at investor events alongside scientific conferences.
Beyond the science and business side, I will also reflect on what it means to start a family while working in a project with startup-like structures, a reality shared by several members of our team.

Speaker: Nina-Marie Burmeister

51 From Studies in Materials Science to Quantum Computing Industry

Looking back on my career, I can say that at the beginning I was not expected to be where I am now. Each stage - from university studies in materials science and engineering, doctoral research in metallurgical physics, and to industry work in cryogenics and quantum computing grew from opportunities, curiosity, and skills developed in the previous stages. My teachers, supervisors and colleagues aroused my interest in research work, and support from my family always encouraged me on this journey.
I enjoyed academic research in the laboratory of Engineering Materials in Aalto University (Espoo, Finland) during my PhD studies and Postdoctoral projects where I learned how to use different experimental equipment, from microscopes to high vacuum systems. I analyzed data and wrote scientific articles, but practical applications and industrial environment were always attractive for me. This brought me to cryogenic company, Bluefors, where my expertise in physics and materials science was beneficial. And then again unexpected turn happened – dilution refrigerators previously used mainly for research in physics became highly demanded for rapidly growing field of quantum computing, and it made me involved also in the field of quantum technology. I started working at Bluefors in Technical Support where I acquired strong technical expertise in cryogenic devices, and then I moved to Technical Sales, where I am working close to academic and industrial customers, helping them in getting necessary equipment and experimental setup for their scientific and technological needs.

Speaker: Olga Todoshchenko (Bluefors GmbH)

52 Computational Physics at Forschungszentrum Jülich

A traditional physics degree equips researchers with the knowledge and critical thinking skills to solve fundamental problems across a diverse range of fields, including quantum mechanics, optics, astrophysics, and solid state physics. However, many real-life problems cannot be solved by hand and must be recast into a format that can be processed by a computer. With rapid advancements in computing infrastructure, scientists now have access to some of the most powerful supercomputers in the world for their research.

This Physics@Work presentation explores the research landscape at Forschungszentrum Jülich (FZJ) and the expanding career pathways into computational physics. The Jülich Supercomputing Centre (JSC) is home to four supercomputers including JUPITER, which is Europe's first exa-scale system. Beyond the technology, this presentation outlines opportunities for physics students, such as the JSC Guest Student Programme on Scientific Computing, and the benefits of building a career at FZJ.

Speaker: Ekaterina Zossimova (Forschungszentrum Jülich)

53 From Academic Physics to Industry: Experiences from Risk Management Consulting

This contribution offers a personal account of the transition from academic physics research to industry. I share my experience of moving into consulting, where I currently work on risk management for financial institutions, an interdisciplinary field that has gained particular relevance in today’s environment of geopolitical uncertainty and volatile international markets.

The talk reflects on what facilitated the transition from academia, which skills from a physics background proved especially valuable, and which aspects of working in industry were unexpected. It also reflects on differences between academic and industrial work environments, particularly with respect to collaboration, decision‑making, and practical impact.

The objective of this contribution is to share lessons learned from this career path and to provide orientation for physicists exploring different professional opportunities,

Speaker: Katharina Dort (KPMG AG WPG)

Career_Talk_Physikerinnentagung.pdf

54 Physics Careers in Practice: Real Paths, Real Stories

In this talk, I will explore the often nonlinear nature of careers in physics, challenging the traditional notion of a single, predefined professional trajectory. Drawing from my own experiences moving between academia and industry, I will highlight how unexpected opportunities, personal decisions, and changing priorities have influenced my career path.

Through candid reflections on challenges along the way and overcoming professional and personal obstacles, this talk provides an honest perspective on shaping a career in physics today. Additionally, I will share insights into the diverse career journeys of women at Menlo Systems, illustrating a range of roles and pathways within a high-tech industry environment.

Speaker: Gabrielle Thomas (Menlo Systems GmbH)

Scientific Session III (Invited talk Julia Stähler)

Convener: Ellen Brennfleck (RPTU Kaiserslautern)

55 The physics of ultrafast CO2 reduction using cryogenic electrons

Global warming requires humanity to reduce atmospheric CO2 significantly - and fast. Chemically, CO2 reduction (i.e. electron attachment) is a vital step for its conversion to less harmful or even useful carbon-based products. One approach to capture CO2 is to freeze it at cryogenic temperatures before chemical modification. Whether or not single electron transfer to CO2 is feasible at these low temperatures and how it proceeds remained unknown.
In our study, we generate isolated electrons on a cryogenic ammonia film by photoexcitation using a pulsed femtosecond laser system. We monitor these solvated electrons using time-resolved photoelectron spectroscopy that provides us with information about their population dynamics and energy. Adding CO2 to the system reduces the electron lifetime and modifies the work function, i.e. surface potential, which we analyse with a rate equation model. In a nutshell, by using these solvated electrons as both, reactant in the electron transfer reaction and spectator of the same, we do not only show that single electron CO2 reduction is possible at 50 K, but also determine the electron transfer time of 77 ± 6 ps. Remarkably, no side reactions are observed: for sufficiently long solvated electron lifetimes, every electron reacts. These results provide mechanistic insights into a notoriously difficult yet technologically critical electron transfer reaction.

Speaker: Julia Stähler (Humboldt-Universität zu Berlin)

56 Tuning Spin-Charge Conversion at the hybrid heavy-metal/ organic semiconductor interface through Chiral Doping

Spintronics, the way forward to device miniaturization, leverages electron spin rather than charge. Though inorganic materials were predominantly given more attention in spin transport studies, organic semiconductor (OSC)/magnetic hybrid interfaces are quickly gaining interest, owing to the flexibility, scalability, and structural tunability of organic materials. Here, we probe the effect of chirality of the OSC on the spin-charge conversion efficiency and spin selectivity in hybrid heterostructures via spin pumping. For this, we probe the inverse spin Hall effect (ISHE) in a ferrimagnetic insulator/ heavy-metal/ OSC heterostructure and systematically dope the conjugated achiral polymer F8T2 with the chiral small molecule 1-aza[6]helicene. When we induce chirality in the F8T2 layer with opposite enantiomers of the dopant molecule, we observe a clear sign reversal in the spin selectivity. These results open the door to chiral doping as an effective tool to control spin injection across hybrid interfaces.

Speaker: Devamrutha I S (Johannes Gutenberg University Mainz)

57 Hybrid Laser–Chemical Functionalization of Stainless Steel Surfaces Using IR Picosecond Laser Pulses for Tailored Hydrophobicity

Functional metallic surfaces with tailored wettability are of increasing interest for applications requiring enhanced corrosion resistance, self-cleaning behaviour, and reduced fouling. While laser texturing and chemical functionalization are established approaches for producing hydrophobic metallic surfaces, their combined effect remains poorly understood. Addressing this challenge is essential for developing robust and scalable processes for functional steel surfaces with tailored wetting behaviour.
This contribution presents a hybrid laser–chemical process using IR-ps-laser pulses for the localized anchoring of stearic acid on stainless steel surfaces. Four surface conditions, including an unstructured reference and three ps laser-generated topographies (LIPSS, bumpy structures, and big bumpy structures), were investigated. Stearic acid was applied using different deposition strategies before selective laser-assisted anchoring. The influence of surface topography, laser energy input, deposition method, and post-treatment on the resulting wettability was systematically evaluated.
The proposed hybrid process transforms initially hydrophilic laser-structured surfaces into hydrophobic and superhydrophobic surfaces with contact angles up to more than 150°. The results demonstrate that the achievable wettability is governed by the interplay between the initial surface topography and the laser-assisted chemical functionalization. Furthermore, the process window for stable functionalization is strongly influenced by the applied laser energy, while the durability of the hydrophobic effect depends on the underlying surface morphology.
Ongoing work focuses on evaluating the long-term stability and corrosion performance of the functionalized surfaces as well as extending the concept to different liquid media. The presented hybrid laser–chemical approach provides a promising route towards robust, application-specific surface functionalization of steel components.

Speaker: Mareike Schäfer (Institut für Oberflächen- und Schichttechnik GmbH)

58 Controlling Floquet-Feshbach resonances in an ultracold quantum gas

Resonant scattering is central to atomic, molecular, and optical physics and provides a powerful tool for controlling interactions in ultracold quantum gases. In ultracold atomic systems, magnetically tunable Feshbach resonances enable precise control of the interaction strength. Building on our recent demonstration that periodic magnetic-field modulation Floquet-engineers additional Feshbach resonances in an ultracold quantum gas [1], we now further investigate how these resonances depend on the strength of the periodic drive. Numerical calculations reveal a characteristic Bessel-function scaling of the resonance strength depending on the modulation amplitude, where the Bessel order is set by the RF-photon order of the corresponding Floquet-Feshbach resonance. This prediction is supported by first experimental evidence, confirming the expected scaling behavior. The observed amplitude dependence enables selective enhancement or suppression of individual Floquet-Feshbach resonances. These results deepen our understanding of Floquet-engineered scattering resonances and establish a versatile tool for controlling interaction landscapes in driven quantum gases.

[1] A. Guthmann et al., Science Advances 11, eadw3856 (2025)

Speaker: Louisa Marie Kienesberger (RPTU)

59 Making Perovskite Photovoltaics Sustainable – Material Choice Guidelines from a Comprehensive Sustainability Perspective

The research community has urged for broader sustainability considerations to guide the development of next generation photovoltaics (PV). We propose a practical sustainability framework with quantifiable indicators for ecological impact, planetary boundaries, social risks, and supply constraints. We apply this framework to raw material mining for a large-scale deployment scenario of perovskite PV.
For both ecological and social impacts, principal component analysis is applied to (social) life cycle impact assessment indicators to identify six representative parameters that capture most relevant impacts. Supply risk is assessed using eight risk indicators. Impacts relative to planetary boundaries are quantified by allocating a representative share of the safe operating space to the PV industry using a grandfathering approach.
The results demonstrates that planetary boundaries are a valuable reference point, but insufficient on their own, as materials within the allocated safe operating space may still pose local environmental, social, or supply-related concerns. Several key materials in particular indium, tin, and iodine are associated with elevated supply constraints. Perovskite PV substantially reduce the environmental impact compared to coal-based electricity generation. Yet, the material selection can significantly influence the environmental profile of PV technologies, as the environmental impact of the materials vary by up to five orders of magnitude. We find that the social risk assessment needs to be carried out at a granular scale. A country-level perspective reveals that high shares of all relevant materials for perovskite PV are mined in countries with high social risk factors.
This study shows that clean energy technologies must be evaluated beyond performance and climate-mitigation potential, as their material requirements may pose environmental, social, and supply-related risks. This mandates trade-offs in the technology development process.

Speaker: Lea Obermüller

Scientific Session IV (Invited talk Maria Dienerowitz)

Convener: Eva Rexigel

60 Observing molecular motors at work: trapping single molecules in solution

Molecular motors are the tiny building blocks of life and are key to a wide range of biological functions at the molecular level. They change their shape upon interacting with a substrate molecule. Identifying these conformational changes is critical to understanding the intricate catalysis and signalling processes of a cell. Since the lateral dimensions of molecular motors are two orders of magnitude below the diffraction limit, standard microscopy cannot resolve them. Fluorescence microscopy techniques and methods such as smFRET (single-molecule Förster resonance energy transfer) provide the tools to locate single molecules and observe their conformational changes. In their natural environment, these molecules diffuse freely in solution. Brownian motion renders them challenging to observe since they only spend a few milliseconds within the observation volume. This contribution presents a way to investigate molecular motors at work in real time by extending the observation time from milliseconds to seconds with electrokinetic trapping. By tracking the position of a diffusing molecule, it is possible to apply an electric field that acts on the surface charge of the molecule and pushes it back to the centre of the observation volume. This enables us to examine the rotation of FoF1-ATP synthase, a protein present in almost every living organism and central to cellular energy conversion, as well as the state transitions of the Rep helicase, which is key to DNA replication by separating double-stranded DNA into single strands

Speaker: Maria Dienerowitz (Ernst-Abbe-Hochschule Jena University of Applied Sciences)

61 sSNOM-driven modeling of the electric field-resolved response of biological cells

The proper function of cells is directly related to the subcellular compartmentalization and spatial distribution of a broad range of molecular species, from enzymes to metabolites and signaling molecules. Determining the spatial distribution of biomolecules within cells is therefore crucial for understanding fundamental cellular mechanisms; yet there is a lack of technologies capable of in vivo, label-free chemical mapping of subcellular structures with the necessary high sensitivity, chemical specificity, and spatial resolution.
Field-resolved spectroscopy (FRS) has shown unprecedented sensitivity and dynamic range [1] and is therefore capable of detecting chemical species within a wide range of concentrations. We envision that FRS combined with near-field microscopy provides a uniquely well-suited configuration for subcellular, label-free chemical imaging of living cells. Spatially resolving the near-field field-resolved light-matter interactions via electro-optic sampling, as demonstrated for the first time down to the near-infrared spectral range [2], can deliver sensitivity to low chemical concentrations and spatial resolution beyond the diffraction limit.
To understand the complex near-field interactions, contrast, and resolution, we perform finite-difference time-domain simulations using the open-source nonlinear optics simulation software Lightwave Explorer [3]. Here, we define the subcellular structure and organelle material properties of the green alga C. reinhardtii based on experimental data from scattering-type scanning near-field optical microscopy (sSNOM) [4]. Namely, the internal cell structure is defined according to atomic force microscopy images, and the index of refraction and extinction coefficients are derived from scattered near-field spectra, each recorded on a specific organelle.
This numerical study is crucial for guiding our current efforts in setting up a near-field FRS microscope and subsequent FRS data analysis and interpretation.

Speaker: Katerina Kanevche (RPTU - Kaiserslautern)

62 ForMOST: Energy Storage For the Future

The man-made climate crisis is, irrefutably, one of the greatest challenges of the 21st century. Scientists across the entire globe and every research field have put forth possible solutions in an effort to mitigate its effects and slow its progress. The MOST concept, short for “Molecular Solar Thermal”, is focused on the development of organic photoswitches that transform into high-energy isomers upon irradiation. These thermally meta-stable (ideally long-lived) isomers, upon contact with specifically developed catalysts, return back into their initial lower energy states. The energy difference between the two isomers will be released in the form of heat, which is e.g. transferred into the water-circulation system of a building.

Figure 1: Schematic representation of the MOST concept.

The Wachtveitl Group, as part of the ForMOST research group (3), carries out not only the fundamental photophysical characterization of MOST compounds but also investigates ultrafast photoreactions using transient absorption spectroscopy (4–6). Here, we present insights into systematically substituted azobenzenes to highlight the design principles at the centre of efficient photoswitch design (manuscript in preparation).

---

References
1. B. Parida, S. Iniyan, R. Goic, Renewable and Sustainable Energy Reviews. 15, 1625–1636 (2011).
2. D. Kim, K. K. Sakimoto, D. Hong, P. Yang, Angew Chem Int Ed. 54, 3259–3266 (2015).
3. H. A. Wegner et al., DFG Research Group 5499 - FORMOST. DFG-Forschungsgruppe FOR 5499, (available at https://www.uni-giessen.de/de/forschung/aktuell/formost). Last accessed: July 29, 2026
4. T. Saßmannshausen et al., Angew Chem Int Ed. 63, e202314112 (2024).
5. D. Sun et al., Chemistry A European J. 31, e01976 (2025).
6. S. M. Biebl et al., J. Am. Chem. Soc. 148, 10776–10787 (2026).

Speaker: Merle Strack (Goethe Universität Frankfurt am Main)

63 Orbitals in photonic waveguides enable non-dimerized SSH-chains

Quantum phenomena in condensed matter that are difficult to access experimentally can be investigated using photonic analog quantum simulation, where classical light emulates quantum dynamics. In coupled optical waveguide arrays, evanescent coupling mimics electronic tunneling, enabling the study of tunable band structures and topological effects. Topological materials exhibit topologically protected properties that remain robust even in the presence of disorder. This remarkable resilience has made topology a subject of longstanding interest in condensed matter physics. One of the most widely studied examples is the Su–Schrieffer–Heeger (SSH) model, typically realized by alternating strong and weak couplings in dimerized waveguide lattices, giving rise to topological edge states. To date, the SSH model and many other condensed matter phenomena have been investigated in photonic waveguide systems almost exclusively using the fundamental Gaussian mode as the input. Here, we extend this framework by exploiting higher-order transverse electromagnetic (TEM) modes as an additional degree of freedom. We demonstrate that the spatial structure of these modes alone can induce the alternating coupling required for the SSH model, eliminating the need for a physically dimerized waveguide lattice. This approach provides a new route to engineering topological photonic systems through modal control rather than structural modulation.

Speaker: Sabrina Hammel (RPTU University Kaiserslautern-Landau, Department of Physics and State Research Center OPTIMAS, Kaiserslautern, Germany)

64 Nanofabrication Approaches for Integrated Quantum Photonics

Quantum technologies are reshaping our understanding of computation and communication, promising capabilities fundamentally beyond classical limits. Among the many physical platforms under investigation, solid-state emitters stand out for their potential scalability and on-chip integrability — making them attractive building blocks for future quantum network nodes.
Color centres in diamond are particularly compelling candidates, combining exceptional optical coherence with long-lived spin states. Yet extracting useful signal from single emitters remains a central challenge: efficient, coherent photon emission is essential for both computation and communication protocols, and bulk diamond is notoriously uncooperative in this regard.
Various approaches have been explored to overcome these limitations — thin membranes, nanodiamonds, and structured bulk diamond among them. This talk focuses on the last: integrating emitters into photonic structures fabricated directly in diamond. Waveguides offer a natural first step, routing single photons on-chip and dramatically improving collection efficiency compared to bulk. Building on this, coupling emitters to resonator structures introduces cavity quantum electrodynamic effects, further enhancing emission rates and light-matter interaction — as demonstrated in nanobeam and photonic crystal cavities, open microcavities, and ring resonators.
The key challenge underlying all of this is fabrication. Here we present our nanofabrication approach for diamond photonic structures and characterise the resulting devices — from waveguides to resonators. We show that the process preserves emitter properties, an essential but often overlooked requirement. Finally, we offer a glimpse of the experiments these structures are now enabling. While robustness and yield remain active areas of development, these results demonstrate a viable path toward integrated diamond photonic devices for quantum applications.

Speaker: Victoria Voinkova (University of Stuttgart)

Tue: Company Exhibition Tuesday

12:30 Lunch

Equal Opportunities: Panel Discussion

Convener: Natasha Compes

65 Panel on Equal Opportunities Measures

In this interactive panel discussion, we will discuss measures to enhance equal opportunities and diversity.
Panelists:
• Karoline Irschara (Atom*innen)
• Stefanie Wittich (Uni Marburg)
• representative (Women4Quantum)
• Anna Voigt (Nationales MINT Forum, AG Frauen 4.0)

Scientific Session V (Invited talk Angela Wittmann)

Convener: Alena Erlenbach

66 Chiralitronics: Exploring the interplay between spin and chirality

Chirality is omnipresent in nature, bridging magnetic and molecular spin phenomena. At the core of this connection lies the chiral-induced spin selectivity (CISS) effect, describing the highly efficient generation of spin polarized currents in chiral molecules. Despite extensive experimental evidence, the underlying mechanisms of CISS remain debated. Here, we explore how chirality is directly linked to the intrinsic magnetic moments in molecules and how molecular design can be harnessed to control spin phenomena at hybrid chiral molecule magnetic interfaces. Our findings pave a pathway towards functional "chiralitronic" devices – turning a fundamental puzzle into a technological opportunity.

Speaker: Angela Wittmann (Johannes Gutenberg University Mainz)

67 Nitrogen-Vacancy Center Diamond Quantum Sensing for Applications in Materials Science, Chemistry and Biology

Nitrogen Vacancy (NV) centers in diamond have emerged as versatile quantum sensors, enabling nanoscale detection of magnetic and electric fields, temperature shifts, strain and chemical environments under ambient conditions. The unique spin properties of NV centers combined with the exceptional properties of diamond provide a powerful platform for investigating physical, chemical, and biological systems with high spatial resolution.
Our research focuses on the application of NV-based quantum sensing techniques using several experimental platforms including confocal microscopy, scanning NV magnetometry, (cryo-) widefield microscope and spin-to-charge conversion microscopy. These approaches are employed to study two-dimensional and nanostructured materials, perform nanoscale thermometry and detect paramagnetic species via T₁ relaxometry. In addition, we explore fluorescence-based techniques such as Förster Resonance Energy Transfer (FRET) using NV-bulk diamonds and photosynthetic molecules.
By combining advanced optical microscopy with quantum sensing, our work contributes to the development of robust, non-invasive sensing technologies capable of addressing fundamental questions in condensed matter physics, materials science, chemistry, and biology.

References:
J.P. Leibold, L.M. Todenhagen, M. Althammer, N. Khera, S. Levashov, E. Neu, M.S. Brandt, H. Huebl, D.B. Bucher, Influence of Platinum Thin Films on the Photophysical and Quantum Properties of Near-Surface NV Centers, Adv. Optical Mater.14, no. 7 (2026): e03544
S. Westrich, N. Oshnik, N. Thiele, N. Burmeister, Y. Abdedou, N. Khera, S.J. Müller-Schüssele, E. Neu, FRET Between NV Centers In Diamond And Chlorophyll Molecules: A Novel Resource For Multimodal Sensing And Imaging In Plant Cells, Advanced Optical Materials (2026): e00003
E. Herbst, S. Westrich, A. Erlenbach, J. Gutsche, M. Wächtler, E. Neu, Towards Application of Nanodiamonds for in-situ Monitoring of Radicals in Liquid Phase Chemical Reactions, arXiv

Speaker: Emma Herbst (RPTU Kaiserslautern-Landau)

68 Repetitive readout for sensitivity enhancement in ensemble NV-diamond NMR

Nitrogen-vacancy (NV) centers in diamond are promising quantum sensors for nuclear magnetic resonance (NMR) on micro- and nanoscale sample volumes. At the Bucher Group, we are developing this technology to probe microscopic and complex biological systems. A key challenge is sensitivity: Small samples contain fewer nuclear spins and therefore generate weak NMR signals. In ensemble NV sensing, this weak signal is detected through a spin-dependent change in fluorescence. However, optical readout has limited contrast and photon collection efficiency, so only a fraction of the spin-state information is converted into a measurable optical signal in each cycle. Repetitive readout (RR) addresses this limitation by improving the effective readout fidelity.
RR is based on a concept from quantum information experiments: spin information can be transferred from one quantum system to another. In NV centers, the optically readable electron spin can be coupled to a nearby nuclear spin, which acts as a longer-lived memory. The spin information is first stored in this nuclear spin memory and then repeatedly mapped back onto the electron spin, where it can be read out optically. This RR process increases the information obtained from one spin-state preparation, improving the signal-to-noise ratio per cycle and thereby increasing the sensitivity of NV-based NMR measurements.
The aim of this work is to implement and evaluate RR as a modular sensitivity enhancement for existing ensemble NV-NMR measurement protocols. Once implemented, it will be incorporated into different experimental schemes. We will further investigate extensions of the RR protocol and explore their combination with other sensitivity-enhancement strategies to further improve sensitivity. By improving the detection of weak signals, RR can enable NV-NMR measurements on smaller and more challenging microscopic systems, including biological samples and cell-like systems.

Speaker: Kathrin Neuhauser

69 Vectorial spin-to-charge conversion by supramolecular chirality

The phenomenon of the chiral-induced spin selectivity (CISS) effect refers to the spin-polarization of electrons in the presence of chiral molecules or structures. Their potential for high polarization efficiencies makes hybrid chiral molecule / magnet devices promising for efficient and sustainable spintronic devices. Despite various experimental reports on different facets of the CISS effect, understanding the underlying mechanisms is still a major challenge. In this work, we explore the vectorial nature of the CISS effect with supramolecular chiral adsorbates in hybrid metal / chiral molecule heterostructures. Using angle-resolved spin pumping, we inject a pure spin current in a Au thin film to probe the spin-to-charge conversion at the chiral interface. To maximize the polarization efficiency, we investigate the CISS effect in the well-ordered system of Bromium-oxoamide single crystals that are physisorbed on the Au via lamination. Through a combination of in-plane and out-of-plane measurements, we identified a single axis that maximizes the CISS efficiency.
Our results confirm a high sensitivity of the CISS effect to the orientation of the crystal relative to the spin direction, and demonstrate that the CISS effect does not need to rely on chemical bonds, but also works with physisorbed molecular structures. These findings open new ways for the vectorial manipulation and functionalization of hybrid spintronic devices through chirality.

Speaker: Sophie Knewitz (JGU Mainz)

70 Effects of high-temperature annealing on SiV ensembles in CVD-grown diamond

Monocrystalline diamonds (MCD) embedded with color centers have emerged as promising candidates for applications in quantum optics, namely sensing. Specifically, negatively-charged silicon vacancy centers (SiV) stand out as ideal due to their narrow zero phonon line (ZPL) at 738 nm, coupled with a high Debye-Waller factor of up to 70 %. However, their application remains hindered by the fabrication challenges associated with producing high-quality, dense, homogeneous SiV ensembles.
The plasma-enhanced chemical vapor deposition (PE-CVD) process can be employed to grow nearly relaxed ensembles of high densities (up to 1013 cm-3). We employed a slow growth rate (tens of nm/hour) on pre-selected MCD substrates, aiming to achieve high homogeneity of centers and low stress in the diamond matrix. The concentration of SiH4 gas, used as a Si precursor, was varied in order to investigate its effects on the optical properties of SiVs.
To further optimize the material quality, the grown samples were subsequently subjected to high-temperature annealing in the range of 600–1200 °C. High-temperature annealing is a widely used post-processing technique that promotes the formation of SiV centers through vacancy diffusion and pairing with silicon atoms. We observe a pronounced increase in the absolute ZPL room-temperature photoluminescence intensity with increasing annealing temperature, accompanied by enhanced low-temperature ZPL splitting. Pump–probe spectroscopy and PL decay measurements were further employed to investigate the time-resolved processes, while Raman spectroscopy was employed to characterize possible structural changes in the material.

Speaker: Irena Hlaváč Bydžovská (Institute of Physics CAS)

Scientific Session VI (Invited talk Viola Vogel)

Convener: Maren Hoock (RPTU Kaiserslautern-Landau)

71 From Single Molecule Mechanics towards the Clinic

Single-molecule mechanics emerged in the late twentieth century from the convergence of polymer physics, biophysics and new force-measurement technologies that made it possible to pull, bend and unfold individual biomolecules rather than infer their behavior from ensemble averages. Optical and magnetic tweezers, as well as atomic force microscopy revealed that biomolecules are not passive structural entities, but mechanically responsive systems whose conformations, binding sites and lifetimes can be regulated by force. Despite their profound impact on biophysics, most classical single-molecule mechanics studies have not yet translated directly into routine clinical applications. The field is now moving toward clinical relevance, as single-molecule insights are getting converted into scalable probes and assays that report mechanically regulated molecular states in tissues. Here we discuss the development of tension-sensitive extracellular matrix nanoprobes which can distinguish between stretched (healthy organ tissues) and relaxed (pathological organ tissues) states of fibronectin fibers as found in the extracellular matrix of tissues. Distinguishing between stretched and relaxed fibronectin fibers introduces a novel and clinically meaningful class of “mechano-markers.” These mechanobiological markers go beyond traditional diagnostics, which rely solely on detecting molecular presence through antibody tests, by uncovering how disease alters the physical properties of extracellular matrix components.

Speaker: Viola Vogel (ETH Zurich)

72 From Plant Virus Templates to Virus-Based Nanoactuators

Plant viruses represent highly uniform and genetically programmable nanoscale building blocks for bottom-up nanotechnology. Over the past years, we have used the icosahedral Tomato Bushy Stunt Virus (TBSV, diameter ~ 30 nm) as a versatile platform for the fabrication of ordered virus-based nanostructures. This work summarizes a research line developed in our group from virus self-assembly and pattern formation to multilayer virus architectures and the first TBSV-templated nanoactuator system based on upright M13 viruses (rod-shaped bacteriophages, 800 nm long, diameter 6 nm).
Starting from the controlled self-assembly of genetically modified TBSV particles, we demonstrated how parameters like electrostatic interactions and virus concentration govern the formation of highly ordered two-dimensional virus monolayers on solid substrates. Subsequently, directed patterning approaches based on focused ion beam lithography and FluidFM enabled the fabrication of predefined 2D virus architectures (top-down and bottom-up) with micrometer and sub-micrometer resolution.
To overcome the limited stability of purely electrostatic assemblies, specific molecular recognition systems were introduced. Covalently immobilized Strep-Tactin layers in combination with Strep-Tag II modified TBSV particles yielded highly stable virus monolayers and enabled the realization of multilayer virus architectures through layer-by-layer assembly.
Building on these developments, we recently established a hierarchical virus nanoarchitecture consisting of a covalently immobilized TBSV template and specifically bound filamentous M13 bacteriophages. Modified M13 bacteriophages were immobilized via specific recognition on top of the Strep-Tag II TBSV layer and remained predominantly upright, as verified by high-resolution scanning force microscopy (SFM). The resulting architecture represents an important step toward biologically derived nanoactuators and virus-based electromechanical systems.
The presented work illustrates how fundamental studies on virus self-assembly can evolve into functional hierarchical nanostructures and highlights the potential of plant-virus-based architectures for future biosensing and nanoactuation applications.
[1] A. Lüders, C. Müller, K. Boonrod, G. Krczal, C. Ziegler, Colloids Surf. B 91 (2012) 154–161.
[2] V. Rink, C. Müller-Renno, M. Braun, K. Boonrod, G. Krczal, C. Ziegler, Phys. Status Solidi C 13 (2016) 163–166.
[3] V. Rink, C. Müller-Renno, C. Ziegler et al., Electrostatic Conditions Define the 2D Self-Assembly of Tomato Bushy Stunt Viruses on Solid Surfaces (2017).
[4] C. Müller-Renno, D. Remmel, M. Braun, K. Boonrod, G. Krczal, C. Ziegler, Phys. Status Solidi A 218 (2021) 2100259.
[5] T. He, M. Braun, K. Boonrod, C. Müller-Renno, G. Krczal, C. Ziegler, 2D-Ordered Layers of Tomato Bushy Stunt Virus via Specific Binding (2025).
[6] T. He, C. Zobeley, M. Braun, K. Boonrod, C. Müller-Renno, G. Krczal, C. Ziegler, Layer-by-Layer Assembly of Plant Viruses Utilizing Specific Binding, Phys. Status Solidi A (2025).

Speaker: Christine Müller-Renno (RPTU Kaiserslautern-Landau)

73 Feasibility of the Grovers algorithm for finding gene regulatory networks

In this talk, I will present the feasibility of using the Grover algorithm to reconstruct gene regulatory networks from bioinformatics data. For this purpose, we modify the Grover algorithm to use multiple distinct oracles belonging to different cells and different cell types. We apply the algorithm to simulated and real bioinformatics datasets demonstrating its applicability to noisy data.

Speaker: Greta Sophie Reese (Center for Optical Quantum Technologies, University of Hamburg, 22761 Hamburg, Germany. The Hamburg Centre for Ultrafast Imaging, Hamburg, Germany)

74 Closing the Phosphorus Loop

The essential nutrient phosphorus is mined in only a few regions of the world and is mainly processed into fertilizers distributed worldwide. Its limited availability, together with increasing geopolitical uncertainties, highlights the need for a more resilient and circular phosphorus supply. Recovering phosphorus from wastewater treatment plants (WWTPs) is a promising approach to closing the phosphorus loop (Raniro et al. 2025).
In municipal wastewater treatments (WWTP), phosphorus is removed by biological uptake and, in some countries like Germany, by chemical precipitation, mainly using iron salts (Barjenbruch et al. 2024). As a result, most phosphorus is transferred to sewage sludge, which can be used as resource for phosphorus recovery (Raniro et al. 2025). One recovery approach is the Stuttgart Process, in which phosphorus is released by acidification and subsequently precipitated as struvite using ammonia from the sewage sludge and an external magnesium source (Meyer et al. 2019). At the WWTP Offenburg, phosphorus leaching efficiencies ranged from 40–70% at pH 3.5–4.5 (n = 18) (Meyer et al. 2019). These variations could not be explained by the measured sludge composition or the applied pH alone (Mohn et al. 2017). Further laboratory studies showed that ion concentrations and target pH influence phosphorus leaching but could not fully explain the observed variability (Monea et al. 2020; Keller et al. 2022).
This presentation introduces the motivation for phosphorus recovery from wastewater and presents the current challenges in evaluating a large dataset to better understand the factors affecting the leaching efficiency in the first step of the Stuttgart Process.
This project is funded by the German Research Foundation (Deutsche Forschungsgemeinschaft – DFG) as part of the Research Training Group 2908 "Valuable Wastewater (WERA) - Recovery of Critical Raw Materials by the Example of Phosphorus".

Speaker: Linda Müller (RPTU Kaiserslautern-Landau | REWA)

Physics and Society II

Conveners: Agnes Sandner (Working Group Equal Opportunities (AKC) of the German Physical Society (DPG)), Dagmar Paarmann

75 From Lab to Life: Evidence-Based Insights into Building an Inclusive Quantum Innovation Ecosystem

The International Year of Quantum Science and Technology (2025) highlighted not only the scientific progress of quantum technologies but also the need to accelerate their transition from research laboratories into practical applications. To better understand the factors that enable or hinder this transition, the Working Group on Equal Opportunities (AKC) of the German Physical Society (DPG) conducted a survey among members of DPG working groups and partner networks. A total of 264 completed responses were statistically analyzed [1].
The survey intended to identify the principal barriers perceived by the quantum tech expert and broader community, including high infrastructure costs, limited practical applications, shortages of qualified personnel, industrial resistance, and regulatory challenges. While quantum technology experts prioritize demonstrating practical value through successful proof-of-concept applications, the broader community places greater emphasis on accessibility, education, and workforce development. Analyses further reveal a significant relationship between concerns about skills shortages and the demand for open-source tools and educational resources.
Beyond technological aspects, the survey demonstrates broad awareness that quantum technologies may unintentionally reinforce existing societal inequalities unless diversity and inclusion are integrated into ecosystem design from the outset.
This contribution presents the survey results, key correlations, and their implications for research policy, education, and innovation management. The results suggest that successful quantum ecosystems require not only scientific excellence and technological maturity but also open education, equitable participation, and interdisciplinary collaboration.

[1] Ağanoğlu, R., & Sandner, A. (2026). Vom Labor in die Anwendung: Eine Umfrage des DPG-Arbeitskreises Chancengleichheit identifiziert Wege zur Beschleunigung der Quantentechnologien. Physik Journal, 25(3), 59–61.

Speaker: Ruzin Aganoglu (Working Group Equal Opportunities (AKC) of the German Physical Society (DPG))

76 Equity Lens: A Transparency Tool for Bias-Aware Selection in Physics

Despite growing awareness of structural inequalities in physics, unconscious bias remains a persistent challenge in selection processes – from awards and speaker invitations to hiring. Gender disparity, institutional concentration, and career-stage imbalance often remain invisible until after decisions are made.
This talk introduces Equity Lens, a prototype developed under the Working Group Equal Opportunities (AKC) of the German Physical Society (DPG). It provides committees with a privacy-preserving dashboard of potential bias indicators before final decisions. It does not rank candidates or store individual votes – it makes hidden patterns visible. The tool calculates career-stage-adjusted metrics (m-quotient) and flags gender imbalance, institutional over-representation, and repeat invitations.
Equity Lens was presented as a selected side event at the UN Global Dialogue on AI Governance (Geneva, July 2026) [1]. The prototype is now publicly accessible as a live demo on GitHub and open for feedback [2]. The talk presents the design, feedback, and roadmap toward an open-source tool for fairer selection in physics.

[1] https://www.un.org/global-dialogue-ai-governance/sites/default/files/2026-07/13_o-20_equity_lens_ai_dialogue_concept_note_template_v3_clean1.pdf

[2] https://akc-equity-lens.github.io/equity-lens/

Speaker: Ruzin Aganoglu (Working Group Equal Opportunities (AKC) of the German Physical Society (DPG))

77 Why Diversity Makes Better Physics

Studies have repeatedly demonstrated that diverse teams lead to increased creativity, productivity and innovation - a phenomenon that can be observed in both academic and industrial settings. However, substantial gender imbalances persist in physics: Although the number of women studying physics in Central Europe has grown steadily over the last years, they remain underrepresented at senior levels. In Germany, for example, women hold only 12% of physics professorships, which is clearly too low a proportion to constitute a critical mass.

This presentation will present recent data on gender representation in physics, examine the factors driving these disparities and explain why diversity is essential for the scientific community and beyond. We will showcase best practices and introduce atom*innen, a new interactive platform designed to support and connect women and gender minorities in quantum physics. We will conclude by outlining concrete measures to strengthen inclusion and equal opportunities throughout the physics community.

Speakers: Ulrike Boehm (DPG Arbeitskreis Changengleichheit), Karoline Irschara (Institute for Quantum Optics and Quantum Information, Innsbruck, Austria)

15:30 Coffee Break

Scientific Session VII (Invited talk Katharina Franke)

Convener: Christine Müller-Renno (RPTU Kaiserslautern-Landau)

78 Atomic-scale spectroscopy of magnetic nanostructures on superconductors

In addition to being an ideal tool for imaging and manipulating atoms and molecules on surfaces, the potential of the scanning tunneling microscope (STM) for high-resolution spectroscopy has been recognized in the fields of single-molecule physics, magnetism, and superconductivity.

Here, we use the STM to resolve the interplay of magnetic atoms and molecules with superconducting substrates. The magnetic adsorbates induce bound states, so-called Yu-Shiba-Rusinov (YSR) states, within the superconducting energy gap. These states provide a wide range of opportunities for engineering hybridized states, band formation, and topology. We exploit flexible molecular structures, molecular self-assembly and atomic manipulation to showcase the exquisite control over the corresponding quantum states [1-5].

References

[1] E. Liebhaber, L. M. Rütten, G. Reecht, J. F. Steiner, S. Rohlf, K. Rossnagel, F. von Oppen, K. J. Franke, Nat. Commun. 13, 2160 (2022).
[2] L. M. Rütten, H. Schmid, W. M. J. van Weerdenburg, E. Liebhaber, K. Rossnagel, K. J. Franke, Phys. Rev. B 111, 205424 (2025).
[3] L. M. Rütten, E. Liebhaber, G. Reecht, K. Rossnagel, K. J. Franke, Nanoscale 17, 26811 (2025).
[4] L. M. Rütten, H. Schmid, E. Liebhaber, G. Franceschi, A. Yazdani, G. Reecht, K. Rossnagel, F. von Oppen, K. J. Franke, ACS Nano 18, 30798 (2024).
Oppen, K. J. Franke, ACS Nano 18, 30798 (2024).
[5] L. Farinacci, G. Reecht, F. von Oppen, K. J. Franke, Nat. Commun. 15, 6474 (2024).

Speaker: Katharina Franke (Fachbereich Physik and Halle-Berlin-Regensburg Cluster of Excellence CCE, Freie Universität Berlin, Germany)

79 Refinements of the Eigenstate Thermalization Hypothesis: a Free Probability Perspective

The Eigenstate Thermalization Hypothesis (ETH) provides one of the main paradigms for understanding the emergence of thermal behavior in isolated quantum many-body systems. Recent developments in quantum dynamics have highlighted that a deeper understanding of quantum chaos and thermalization requires going beyond the standard ETH ansatz by considering higher-order correlations, a framework that can be naturally formulated using mathematical tools from free probability theory. In this talk I will discuss recent progress in this direction, focusing on how the property of local rotational invariance refines the full ETH framework. I will then briefly present how these ideas are connected to the notion of freeness, illustrating how free probability provides a unifying framework for understanding the behavior of complex quantum systems.

Speaker: Elisa Vallini (University of Cologne)

80 Experimental evaluation of total ionizing dose effects in HfO₂-based RRAM 1T1R arrays

Reliable non-volatile memories capable of operating under radiation are essential for harsh-environment applications, such as microsatellites in low Earth orbit (LEO). Radiation-tolerant devices can improve mission reliability while reducing system complexity and the need for additional radiation mitigation techniques. Resistive random-access memory (RRAM) is a promising candidate due to its non-volatility, ion-based resistive switching (RS) mechanism, and multi-level storage capability, which significantly enhances memory density. However, its radiation tolerance is still under investigation.
This work studies the total ionizing dose (TID) effects of HfO₂-based one-transistor-one-resistor (1T1R) RRAM arrays fabricated in IHP’s 130 nm BiCMOS technology under X-ray and γ-ray irradiation. Since the access transistor is the most radiation-sensitive element of the memory cell, the array integrates an enclosed layout transistor (ELT) as a radiation-hardened-by-design (RHBD) solution. Memory cells were programmed into four resistance states, i.e., one high resistance state (HRS) and three low resistance states (LRSs), and irradiated up to 1 Mrad(Si). Retention was periodically monitored during irradiation under worst-case conditions, while the electrical characteristics of the stand-alone ELT were also evaluated.
The results indicate a high degree of radiation tolerance under both irradiation sources, with no resistance drift observed during γ-ray exposure. At a higher X-ray dose rate, the stability of the cells was state-dependent. While cells programmed to the LRS showed no resistance drift, approximately 42% of the cells in HRS exhibited resistance variations. The ELT exhibited negligible variations in its electrical characteristics under both irradiation sources. Furthermore, all cells could be reprogrammed and no degradation of the RS parameters was observed after 1 Mrad(Si) exposure.
This work was financially supported by the DFG under Project 551916740.

Speaker: Mar Puigibert Perez (IHP - Leibniz Institute for High Performance Microelectronics)

81 Superhyperfine interaction and spin dynamics in ¹⁷¹·¹⁷³Yb:LiYF₄

Rare-earth ions in crystalline hosts are promising candidates for quantum memory applications, offering long-lived nuclear spin states and frequency compatibility with superconducting quantum circuits. A key factor limiting spin coherence in these systems is the interaction of the electron spin with the surrounding nuclear spin bath, the superhyperfine (SHF) interaction, which can be also exploited for longer storage of coherence into the nuclear spin states. We investigate the SHF interaction of ¹⁷¹Yb³⁺ and ¹⁷³Yb³⁺ impurity ions co-doped in an Er:⁷LiYF₄ crystal at millikelvin temperatures using broadband electron spin resonance spectroscopy based on superconducting coplanar waveguides. By sweeping an external magnetic field from zero to 50 mT with the field applied along the crystal c-axis, we map the spin transition spectra and resolve their SHF substructure arising from the eight nearest-neighbor ¹⁹F nuclei in the S₄ site symmetry of LiYF₄. Complementary measurements with the field perpendicular to the c-axis are also performed. We identify Zero First-Order Zeeman (ZEFOZ) transitions and characterize their spectral positions. Spin Hamiltonian simulations are overlaid on the two-dimensional experimental spectra, allowing direct comparison. Pulsed spin echo measurements are performed near the ZEFOZ transitions, where free induction decay signals are observed and Hahn echo sequences aim to characterize the coherence time T₂.

Speaker: Melike Calhan (Walther-Meißner-Institut, Bayerische Akademie der Wissenschaften, School of Natural Sciences, Technische Universität München)

Scientific Session VIII (Invited talk Gesa Welker)

Convener: Emma Herbst (RPTU Kaiserslautern-Landau)

82 Magnetic Quantum Sensing with Single-Spin Sensors

Dr. Gesa Welker, Eindhoven University of Technology
Quantum sensing is one of the pillars in the currently ongoing second quantum revolution. In my talk, I will explain how impurities in diamond, quantum sensors of just the size of an atom, can detect extremely tiny magnetic fields. Such so-called color centers in diamond are used for many applications, they have e.g. been used to map the Earth’s magnetic field. I will also show how muons produced at particle accelerators can be implanted in samples and used as tiny magnetic field sensors, every muon being one quantum sensor.

Speaker: Gesa Welker (Delft University of Technology)

83 Spin-Selective Optical Cycles in Color Centers

Prototypical Color Centers in semiconductors, such as the $\mathrm{NV^-}$-center in diamond, the Silicon vacancy ($\mathrm{V_{Si}^-}$) and the di-vacancy ($\mathrm{V_{C}V_{Si}}$) in 4H-Silicon carbide (4H-SiC) are promising candidates for the implementation of quantum bits (qubits) in semiconductors. Their coupled electron spins exhibit correlated high- and low-spin states,enabling spin-selective manipulation via optical excitation, magnetic fields or strain. Optical spin manipulation involves excitations within the high-spin multiplet and spin-selective non-radiative transitions (intersystem-crossing, ISC), mediated by spin-orbit,spin-spin, and electron-phonon interactions. Together with the zero-field splitting in ground and excited states, these processes enable diverse spin-photon protocols. A quantitative understanding of spin-selective interactions is essential for optimizing such quantum interfaces. We describe Color Centers using an embedding approach based on a configuration-interaction (CI) Hamiltonian with an effective screened Coulomb interaction [1,2], extended by a perturbative treatment of the spin-orbit coupling [3]. In combination with the electron-phonon coupling this framework provides access to spin-selective transition rates and photo ionization [3,4]. We demonstrate the approach by analyzing the spin-selective optical cycle of the $\mathrm{V_{Si}^-}$ in 4H-SiC. Our results yield a quantitative understanding of the underlying processes and open the door to theory-guided qubit engineering.

[1] M. Bockstedte et al., npj Quantum Materials 3, 31 (2018).
[2] M. Niethammer et al., Nano Letter 19, 7173 (2019).
[3] M. Neubauer et al., Key Eng. Mat. 984, 1 (2023).
[4] T. Steidl et al., Nat. Commun. 16, 4669 (2025).

Speaker: Mirjam Neubauer

84 Quantum sensing with spin defects in emerging platforms beyond diamond

Optically addressable spin systems, such as nitrogen-vacancy (NV) centers in diamond, have been widely studied for quantum sensing applications. Recently, our group demonstrated two novel quantum sensing platforms based on naturally occurring spin defects in boron nitride nanotubes (BNNTs) (1,2). These defects combine high surface area with omnidirectional spin control—key features that enhance sensing performance. We present strong evidence that these defects form weakly coupled spin pairs, akin to recently identified centers in hBN (3), and demonstrate coherent spin control over ensembles embedded within dense, microscale BNNT networks. Through dynamical decoupling, we enhance spin coherence times by over 300-fold and achieve high-resolution detection of radiofrequency signals. Integration of the BNNT mesh sensor into a microfluidic platform enables chemical sensing of paramagnetic ions in solution, with detectable concentrations nearly 1000 times lower than those reported for comparable hBN-based systems (4,5). This highly porous and flexible architecture positions BNNTs as a powerful new host material for quantum sensing. (2) Flavin-based cryptochrome proteins: These proteins generate radical pairs upon optical excitation and exhibit optically detected magnetic resonance, a hallmark of electronic spin manipulation essential for quantum sensing (6). We demonstrated that the optical spin interface and associated quantum properties can be tuned via protein structural engineering. Radical pairs within proteins thus provide a versatile biomolecular platform for quantum sensing. Compared to solid-state spin systems, protein-based quantum sensors offer unique advantages for biosensing due to their genetic encodability and the potential for evolutionary design.

Speaker: Linyan Nie (Technical University of Munich)

85 A Portable Fiber-Based NV Quantum Sensor for Bioinspired Magnetic Field Detection

Over the past decade, nitrogen-vacancy (NV) centers in diamond have emerged as a powerful platform for quantum sensing, generating increasing interest in biomedical applications due to their high spatial resolution, inherent biocompatibility, and ability to operate under ambient conditions. One of the key advantages of NV-based sensors is the chemical and mechanical robustness of the diamond host material, which allows direct contact with biological samples while enabling the detection of nearby magnetic signals such as those produced by muscle activity or nerve impulses.
While a variety of fiber-integrated NV sensor configurations have been demonstrated, most suffer from limited portability, restricting their usability in surgical or in vivo environments where compactness and flexibility are a crucial requirement.
This work presents a compact, flexible, and portable fiber-based NV sensor specifically designed to address these challenges. Our device is fabricated using direct laser writing, to create functional microstructures composed of silver and polymer materials directly on the tip of an optical fiber. The silver structure enables efficient microwave excitation of the NV centers, while the polymer component provides mechanical stabilization for a 40 μm diamond crystal mounted at the fiber tip and assists in the alignment of optical excitation and fluorescence collection.
We validate the sensor's performance by detecting bioinspired electrical signals. The device achieves a magnetic field sensitivity of 6 nT/√Hz under ambient conditions. This demonstration is a step towards future use in minimally invasive biomedical diagnostics and intraoperative applications.

Speaker: Alena Erlenbach

Scientific Session XIV: Particle Physics

Convener: Volker Schünemann (RPTU University Kaiserslautern-Landau)

86 Background Suppression in the SHiP Experiment with the SBT

SHiP (Search for Hidden Particles) will be a fixed-target experiment at CERN’s SPS designed to probe long-lived feebly interacting particles (FIPs) in the GeV range. Installed in a dedicated beam-dump facility in the ECN3 cavern, SHiP will use 400 GeV/c SPS protons to accumulate $6\cdot10^{20}$ protons on target over 15 years, while reducing backgrounds from the intense muon and neutrino flux to a negligible level. An essential component is the Surrounding Background Tagger (SBT), which encloses a 50 m helium-filled decay volume and tags charged particles entering from the sides as well as inelastic interactions occurring in the Helium or within the SBT itself. The SBT consists of aluminum cells filled with a liquid scintillator. Each cell contains two wavelength-shifting optical modules (WOMs) that detect scintillation light produced when charged particles traverse the detector. This contribution presents the SBT, its design and functionality, as well as simulation studies investigating the suppression of the muon-induced background.

Speaker: Jasmin Weiß

Physikerinnentagung_SBT.pdf

87 The SHiP/NA67 experiment at the ECN3 high-intensity beam facility at the CERN SPS

Search for Hidden Particles (SHiP/NA67) is a new general-purpose, high-intensity beam dump experiment at CERN approved in 2024 and designed to explore the largely uncharted domain of feebly interacting particles with masses from 100 MeV to a few GeV. These particles are predicted by a large number of theories beyond the Standard Model capable of explaining phenomena such as dark matter, neutrino oscillations, and the origin of the baryon asymmetry in the Universe.
By fully exploiting the intense 400 GeV proton beam of CERN’s Super Proton Synchrotron, SHiP will provide leading sensitivity to most models predicting particles within this mass range, such as heavy neutral leptons, dark photons, axion-like particles and light dark matter. In addition, the intense flux of neutrinos of all flavours produced in the beam dump will enable a rich programme of Standard Model and neutrino physics with notably millions of neutrinos expected to be detected over approximately 15 years of operation and the potential first observation of tau antineutrinos.
This contribution summarises the physics motivation, the experimental concept and the detectors systems and outlines the expected sensitivity and timeline.

Speaker: Ida Woestheinrich (Humboldt University of Berlin)

SHiP_experiment_Woestheinich_DPT.pdf

88 BOLT: Imaging Lightning and Terrestrial Gamma-ray Flashes at the Pierre Auger Observatory$^*$

The detectors of the Pierre Auger Observatory, primarily designed to observe ultra-high energy cosmic rays and identify their sources, simultaneously take advantage of their sensitivity and large coverage area to detect transient luminous events and terrestrial gamma-ray flashes (TGFs), atmospheric phenomena closely linked to lightning and thunderstorms. Owing to their sensitivity to high-energy photons, the 1600 water-Cherenkov detectors recently revealed a unique characteristic of downward TGFs. However, the TGF production mechanism is not well understood and requires further observations of lightning processes in their earliest stages. To meet this challenge, the Broadband Observatory of Lightning and TGFs (BOLT) is a detector set up to image lightning propagation in three dimensions with high temporal resolution using radio interferometry. With eleven modified Auger Engineering Radio Array (AERA) stations and their bandwidth ranging from 30 – 80 MHz, the necessary spatial and temporal resolution can be provided.
This contribution presents recent hardware developments, including progress toward selective triggering and precision timing, and the first field data recorded with BOLT, which have been analyzed using the knowledge gained from previous AERA measurements. Together with the existing detector systems of the Pierre Auger Observatory, BOLT establishes a powerful experimental framework for advancing our understanding of lightning physics and associated high-energy atmospheric phenomena.

$^*$Supported by BMBF Verbundforschung Astroteilchenphysik (Vorhaben 05A23PX1)

Speaker: Melanie Joan Weitz (Bergische Universität Wuppertal)

89 Strangeness fluctuations in the HADES experiment*

Fluctuations of conserved charges such as baryon number, electric charge, and strangeness are effective probes of the QCD phase diagram. Their higher-order cumulants are particularly sensitive to critical phenomena and remain an important focus of current heavy-ion research.

In this work, an exploratory study of strangeness fluctuations in Ag+Ag collisions at $\sqrt{s_{NN}} = 2.55~\text{GeV}$, measured with the High Acceptance Di-Electron Spectrometer (HADES), a fixed-target experiment at GSI, Germany, is presented. Operating in the $1–2A~\text{GeV}$ regime, HADES accesses QCD medium at high net-baryon density and low temperature, providing complementary coverage to higher-energy programs.
The very low strange-hadron yields at these energies necessitate robust particle identification. Therefore, a fuzzy-logic-based probabilistic technique is employed to reconstruct strange-hadron multiplicity moments.

This contribution focuses on the feasibility study of strangeness fluctuations at HADES, including the identification and reconstruction performance for strange particles, and the resulting cumulants of their multiplicity distributions.

$^*$This work is supported by ``Netzwerke 2021'', an initiative of the Ministry of Culture and Science of the State of Northrhine Westphalia.

Speaker: Athira Sreejith (Bergische Universität Wuppertal)

DPT2026_Athira.pdf

Postersession II

90 Navigating Quantum Education at Uni-level: Didactic Pathways and a Roadmap for Textbook Selection

Quantum mechanics (QM) textbooks both shape classroom instruction and reflect the pedagogical strategies of the lecturers and researchers who write them. This study analyzes the didactic structures of university-level QM textbooks across nations and eras by mapping the chapter-level placement of mathematical formalisms, illustrative physical systems, foundations and interpretations. The comparison reveals distinct pedagogical priorities: what is treated as fundamental, what is introduced as accessible, how much is connected to modern developments, and how conceptual understanding is balanced against formal competence. It also identifies a shift from traditional “wave-first” and “spin-first” trajectories toward more diverse approaches, including concept-oriented and synthetic presentat ions that connect formalism, experiment, and applications. Based on these differences, we propose a roadmap for students, lecturers, curriculum designers, and independent learners seeking textbooks aligned with their backgrounds, goals, and visions of quantum education.

Speaker: Yajie Liang

91 Evaluating natural magnitudes in the photometric system of astronomical photo plates

Accurate photometric calibration of astronomical photographic plates remains a fundamental challenge in astronomy due to the mismatch of spectral sensitivities of photographic plates and pass bands of modern calibration catalogs.
We intend to derive consistent natural magnitudes for celestial sources within the intrinsic photometric systems of astronomical photographic plates by using Gaia Data Release 3 (DR3) blue-photometer (BP) and red-photometer (RP) low-resolution spectral data, and to show its superiority over former methods.
We compiled spectral characteristic data for emulsions and filters applied in photometric observations using glass plates. The collected color sensitivities, modified by atmospheric reddening depending on the air mass, were then used to compute accurate natural magnitudes and fluxes of objects in the photographic plates through synthetic photometry. These natural magnitudes are then compared with results from the color-term method used to compile the data in existing photoplate archives.
We were able to reveal systematic errors of the existing data in the range of $\pm 0.3$ mag and higher. In addition, the presented method allows for an accommodation of stars with similar color index but of different luminosity classes as well as an effective correction of atmospheric reddening at higher air masses (approximately 0.2 mag). First results of the calibration of a photoplate using the new natural magnitudes are presented.

Speaker: Maryam Raouph (Marburg University)

92 Characterizing the coupling between plasmonic nano-antennas and an atomically thin semiconductor

The combination of plasmonic nano-antennas and atomically thin semiconductors offers an ideal platform to explore light matter coupling on the nanoscale. One reason is that the natural Bohr radius of excitons in these materials is in the range of a few nanometers and therefore significantly smaller than the optical diffraction limit, i.e. the resolution of standard far-field optical setups. In contrast the near-fields of plasmonic nano-antennas naturally provide sub-diffraction limited confinement of light. It has been shown that the optical spectra of such hybrid nano-systems have distinct spectral features [1, 2]. In addition, the coupling results in the generation of enhanced linearly polarized absorption and emission of the involved excitons [1,2].
Here, we report on our first steps using a scattering type scanning near-field microscope to study the optical response of these coupled systems. Through the unprecedented optical resolution, we can expect deeper insights in the interplay between particle plasmons and monolayer excitons. Moreover, we expect the nanoscale optical excitation to actively change the resonance properties of the antenna, contributing to the overall optical properties of the hybrid system.

References
[1] J. Kern et al., ACS Photonics 2, 1260-1265 (2015)
[2] M. M. Petrić et al., Nano Lett. 22, 561-569 (2022)

Speaker: Hannah Unterberg

93 Characterization of Compositionally Tunable InGaAs/InAlAs Core-Shell Nanowire Lasers

Compact and efficient light sources are essential for integrated photonic circuits, yet their direct integration with silicon-based platforms remains challenging due to the inefficient light emission of silicon. III–V semiconductor nanowires offer a promising route towards nanoscale light sources, combining a small footprint and efficient strain relaxation with the direct band gap required for optical gain and lasing.

In this work, InGaAs/InAlAs core–shell nanowires are investigated as individual Fabry–Pérot laser cavities for long-wavelength emission relevant to silicon photonics. Nanowire samples with different nominal indium contents were studied using a combination of optical simulations, growth optimization, structural characterization, and single-nanowire μ-photoluminescence spectroscopy. The simulations were used to guide the design of nanowire geometries supporting guided-mode lasing, while structural characterization provided insight into the morphology of the grown nanowire ensembles.

Photoluminescence measurements confirmed a systematic red shift of the emission with increasing indium content, demonstrating the tunability of the InGaAs/InAlAs material system. Power-dependent measurements on individual lying nanowires revealed a clear transition from spontaneous emission to stimulated emission and lasing, with spectral features consistent with Fabry–Pérot cavity modes. Temperature-dependent measurements further demonstrated lasing from single InGaAs nanowires up to room temperature.

In addition, mode-profile simulations were performed in the experimentally relevant lying-nanowire geometry to support the interpretation of future optical measurements. Overall, these results highlight InGaAs/InAlAs core–shell nanowires as a promising platform for long-wavelength single-nanowire lasers and provide design guidelines for their future integration into photonic circuits.

Speaker: Alicia Robles Pérez (Walter Schottky Institute)

94 A Portable Endstation for Nanobeam X-ray Spectromicroscopy in the Soft and Tender X-ray Range

The combination of scanning transmission X-ray microscopy (STXM) and X-ray fluorescence (XRF) analysis enables the simultaneous acquisition of elemental distribution maps and multiple transmission imaging modes. In the soft and tender X-ray range, this combination has become an increasingly powerful tool for materials science, biomedical, and environmental research.
We present the portable endstation AnImaX (Analytical Imaging with X-rays) for synchrotron-based analytical imaging and spectroscopy with nanometer-scale spatial resolution [1,2]. Originally developed for the P04 beamline at PETRA III (Hamburg), AnImaX is currently operated at the PGM beamline for undulator radiation of the Physikalisch-Technische Bundesanstalt at BESSY II (Berlin), demonstrating its portability and adaptability across synchrotron facilities. Simultaneous acquisition of transmission images and XRF maps is achieved using a 2D detector in transmission mode and a four-segment silicon drift detector with a large solid angle of detection (1.1 sr), enabling dwell times as short as 1 ms, depending on beamline capabilities and sample conditions. The current set of zone plate optics covers a photon energy range of 250–3000 eV.
AnImaX is currently used for studies in environmental science and nanoelectronics for the investigation of memristive devices [3]. In this contribution, we want to highlight recent experiments of the analysis of artificial nanostructures to demonstrate the instruments capabilities. In addition, we will present selected insights from studies of biomedical samples, demonstrating how optimized fluorescence excitation conditions can improve elemental sensitivity and support nanoscale chemical imaging of biologically relevant structures.
[1] L. Lühl et al, J. Synchrotron Radiation 26, 2019, 430-438.
[2] A. Haidl et al, Microscopy and Microanalysis 24(S2), 2018, 230-231.
[3] A. Wählisch et al, Advanced Electronic Materials, 2026, e00784.

Speaker: Mara Mußhoff (Hochschule Koblenz)

95 Appraoching sustainably scalable perovskite photovoltaics

A successful and effective global energy transition requires an enormous expansion of renewable energy technologies at the terawatt scale. Perovskite solar cells have high potential to address this challenge as they are offering high efficiency, cost-effective fabrication and material flexibility. Alongside performance, sustainable development also requires a consistent focus on scalability. In this contribution, I will present an overview on the research activities in our group. Our research thus follows a three-tiered approach including sustainability analysis, solar cell optimization and characterization and ageing methods. As guiding compass our sustainability analyses model solar expansion for cost-efficient climate protection, critically analyze materials and identifies priority measures. Building up on that we are developing printable carbon electrodes for maximum stability and are using a layer system for minimal losses and maximal lifespan. We then perform opto-electrical characterization, customized electronics enabling high-throughput characterization during aging and AI-supported big data analyses. To understand and verify our results we use drift-diffusion-based modelling. Overall, our integrated approach combines sustainability assessment, materials optimization and degradation analysis aiming to advance perovskite photovoltaics that are efficient and sustainably scalable, both economically and ecologically.

Speaker: Hannah König (Uni Marburg)

96 Cold Chemistry with Single Polyatomic Molecular Ions

Polyatomic molecular ions offer new opportunities for precision spectroscopy and quantum control due to their rich internal structure. At the same time, their complex energy levels and lack of cycling transitions makes their state-preparation and readout challenging. I will present a cryogenic trapped-ion experiment which we recently developed and our first results demonstrating chemistry with single molecular ions, enabling control and detection at the level of individual reaction events. We will also discuss how this single-ion methodology opens a new route to studying cold ion-neutral collisions, pushing into the cold regime where quantum effects can influence reaction dynamics. I will also outline our efforts toward quantum logic spectroscopy of polyatomics in which a co-trapped atomic ion serves as a coolant and messenger for the internal state of the molecular ion, enabling non-destructive internal-state identification by mapping molecular information onto an atomic ion for state-resolved reaction control.

Speaker: Prerna Paliwal (University of Basel)

97 Cryogenic Nitrogen Vacancy Magnetometry for Single-Molecule Magnets

Scanning nitrogen-vacancy (NV) magnetometry is a powerful technique for nanoscale magnetic imaging. In this approach, the conventional atomic force microscopy tip is replaced by a diamond nanopillar containing a single NV center, which serves as a highly sensitive local magnetic field sensor. By scanning the NV center over a sample, the magnetic stray field can be mapped with high spatial resolution. While this technique has been widely applied at room temperature to study, for example, magnetic textures in thin films and local current flow patterns, many phenomena of interest—including emergent magnetic phases and superconductivity—only appear at cryogenic temperatures. As the NV center retains its ability to sense magnetic fields at low temperatures, we have been working towards a variable temperature cryogenic scanning NV system. This platform enables nanoscale magnetic imaging of materials at low temperature and offers a unique opportunity to directly probe magnetic phase transitions in quantum materials.

We have recently obtained our first low-temperature magnetic field maps at 7 K, and are now applying the technique to our first target system: single-molecule magnets. These molecules exhibit magnetic hysteresis at low temperatures, making them promising candidates for applications in information storage, molecular spintronics, and quantum computing [1]. The ability of our setup to operate over a broad range of temperatures and timescales makes it well suited for studying the strongly temperature-dependent behaviour of these molecules.

In this poster, we discuss our cryogenic scanning NV magnetometry setup, including experimental challenges associated with low-temperature operation, and present our first measurements on the single-molecule magnet Tb₂@C₈₀(CF₃)-Ih acquired at 7.5 K.

[1] Liu, F., Krylov, D., Spree, L. et al. Nat Commun 8, 16098, (2017)

Speaker: Lotte Boer (Max Planck Institute for Chemical Physics of Solids)

98 Electronic-Structure Descriptors for Stiffness in High-Entropy Transition-Metal Diborides from First-Principles Supercell Modeling

High-entropy transition-metal diborides (HEDBs; HETMB$_2$) retain the hexagonal AlB$_2$ structure while introducing severe multication disorder, raising practical questions about how large and how random a supercell must be for reliable first-principles predictions. Here, density functional theory calculations (ABINIT, PBE, norm-conserving pseudopotentials) are used to connect electronic structure to elastic stiffness, with the bulk modulus determined from near-equilibrium pressure--volume equations of state. Disorder is sampled using multiple cation configurations and two representative model sizes: an ordered 36-atom supercell for systematic composition scans and a 144-atom supercell with random site occupancy for convergence testing. Although larger cells promote like-cation clustering, the key density-of-states features and computed bulk moduli are essentially unchanged with supercell size and specific cation arrangement within numerical uncertainty. Across binary diborides and designed four-component HEDBs, the average metal-sublattice $d$-electron occupancy, $n_{\mathrm{dest}}$, emerges as the primary descriptor: it sets the Fermi-level position relative to the pseudogap and correlates with a monotonic increase in stiffness. Residual variations at fixed $n_{\mathrm{dest}}$ arise from metal-size dispersion, 4$d$/5$d$ substitution, and transition-metal vacancies, with vacancies providing a plausible route to experimentally reduced stiffness in real ceramics.

Speaker: Nebahat Bulut

99 Energy distribution of surface plasmon-induced hot carriers

Are the spectroscopic properties of plasmon- and photon-induced carriers fundamentally different? This question is crucial for advancing plasmonic energy conversion. Initial studies have suggested characteristic energy and momentum distributions for the photoemission of both bulk plasmon resonances and surface plasmons. For surface plasmons, however, the separation of plasmon and photon-induced emission patterns by their inherent spatial and temporal dynamics remains challenging [1].
To further characterize the electron emission pattern of surface plasmons, we combine a femtosecond laser system with a spatial light modulator to generate a vector vortex beam to excite surface plasmon polaritons at an annular structure. Our photoemission electron microscope enables us to compare the spectroscopic properties of photoemitted electrons and those generated by plasmonic emission at the center of the structure, providing valuable insights into the distinct emission mechanisms.
[1] Hartelt et al., ACS Nano 15, 12 (2021), 19559-19569

Speaker: Ellen Brennfleck (RPTU Kaiserslautern)

100 Engineering Germanium-Superconductor Hybrid Interfaces

Germanium has emerged as a promising platform for superconductor–semiconductor hybrid devices [1,2] due to its compatibility with existing CMOS technology, high carrier mobility [3], and a relatively strong spin–orbit coupling [4]. A critical requirement for such hybrid systems is the realization of a transparent and well-defined interface between the superconductor and the semiconductor at the nanoscale.

Achieving this is particularly challenging due to the presence of native oxides on the surface, which can act as barriers to efficient charge transport. In our work, we investigate reactive ion etching based on the gases SF6/CHF3 as a method to remove surface oxides and create a clean superconductor-semiconductor interface.
To quantify the interface quality and device performance, we conducted DC measurements at mK temperatures.

With this method, we aim to fabricate reliable superconductor-germanium contacts, enabling further research into germanium-based Josephson junctions.

Publications/References:
[1] Tosato, A. et al, Commun Mater 4, 23 (2023)
[2] Aggarwal K. et al, Phys. Rev. Research 3, L022005 (2021)
[3] Dobbie A. et al, Appl. Phys. Lett. 101, 172108 (2012)
[4] Mizokuchi R. et al, Appl. Phys. Lett. 111, 063102 (2017)

Speaker: Katarina Stanojević (JARA-FIT Institute for Quantum Information, Forschungszentrum Jülich GmbH and RWTH Aachen University)

101 Gate-Tunable Excitonic Features in TMD Monolayers and Heterostructures

Laura Rojo Guerrero1, Niklas Schmidt1, Elena Blundo1,2, Jonathan J. Finley1,3
1Walter Schottky Institut and TUM School of Natural Sciences, Technische Universität München, Am Coulombwall 4, Garching, Germany
2Physics Department, Sapienza University of Rome, 00185 Rome, Italy
3Munich Center for Quantum Science and Technology (MCQST), Munich, Germany 1
Department of Nanoscale Research, University of Munich, Munich, Germany
Contact Email: laura.rojo@tum.de
Two-dimensional (2D) semiconducting materials provide a unique platform for studying strongly bound excitons and their interactions due to reduced dielectric screening and quantum confinement. By controlling layer composition, twist angle, applied electric field, and doping, both interlayer and intralayer excitons can be engineered.

We investigate gated MoSe2 monolayer and MoSe2-based heterostructure devices using photoluminescence and reflectance contrast spectroscopy. Through these measurements we probe how carrier density influences excitonic resonances and many-body interactions.
This work contributes to a deeper understanding of light-matter interactions in low-dimensional systems and supports the development of next-generation optoelectronic and quantum photonic devices based on 2D materials.

Speaker: Laura Rojo Guerrero (Technical University of Munich)

102 Heralded generation of a three-mode NOON state

Sukhjit P. Singh,1 Elnaz Bazzazi,
2, ∗ Diego N. Bernal-Garc´ıa,1 Simon White,1 Hassan Jamal Latief,3 Alison
Goldingay,3 Sven Rogge,3 Sergei Slussarenko,1 Farzad Ghafari,1 Emanuele Polino,1 and Nora Tischler1
1Queensland Quantum and Advanced Technologies Research Institute,
Centre for Quantum Computation and Communication Technology,
Griffith University, Yuggera Country, Brisbane, Queensland, 4111 Australia
2Department of Physics, Humboldt University of Berlin, Berlin, 12489 Germany
3Centre for Quantum Computation and Communication Technology,
School of Physics, The University of New South Wales, Sydney, NSW 2052, Australia
Entangled states of photons form the foundation of quantum communication, computation, and
metrology. Yet their generation remains fundamentally constrained: in the absence of intrinsic
photon–photon interactions, the generation of such states is inherently probabilistic rather than
deterministic. The prevalent technique of post-selection verifies the creation of an entangled state by
detecting and thus destroying it. Heralding offers a solution in which measuring ancillary photons in
auxiliary modes signals the state generation without the need to measure it. Here, we introduce and
experimentally demonstrate a scheme to generate a three-mode NOON state, where the detection
of a single photon in one heralding mode signifies the presence of the state in three target modes.
We validate the generated state by estimating a fidelity of 0.823 ± 0.018 with respect to an ideal
three-mode NOON state and certifying genuine multipartite entanglement. By virtue of the high
success probability and small resource overhead of our scheme, our work provides a theoretical and
experimental stepping stone for entangled multi-mode state generation, which is realizable with
current technology. These multi-mode entangled states represent a key direction for linear optical
quantum information that is complementary to multi-qubit state encoding. enables.

Speaker: Elnaz Bazzazi (Humboldt-Universität zu Berlin)

103 Interface-Engineered Phonon Localization in Gradient $\text{Si}_x\text{Ge}_{1-x}$ Multilayers for Enhanced Thermoelectrics

Approximately 80\% of global energy is currently lost as low-grade waste heat (300–600 K). While solid-state thermoelectric (TE) generators present a promising solution for waste heat recovery, conventional high-efficiency TE materials are typically toxic and incompatible with standard Complementary Metal-Oxide-Semiconductor (CMOS) manufacturing, severely hindering their large-scale industrial integration. To address this bottleneck, this study demonstrates the potential of non-toxic, fully CMOS-compatible Group IV materials for efficient near-room-temperature TE energy harvesting. The fundamental advantage of our designed $\text{Si}_x\text{Ge}_{1-x}$ multilayer structure lies in a novel fabrication process that enables a continuous Ge concentration gradient from 0\% to 100\%, yielding strain-relaxed layers as evidenced by X-ray diffraction (XRD) and polarization-resolved Raman spectroscopy. Crucially, the engineered interfaces between each $\text{Si}_x\text{Ge}_{1-x}$ layer provide strong phonon scattering, thereby significantly reducing the material's thermal conductivity. Using non-destructive Raman thermometry coupled with analytical models, we accurately determine this reduced thermal conductivity without requiring complex sample preparation. In parallel, Scanning Transmission Electron Microscopy (STEM) reveals ~10 nm dislocations at the interfaces. Our established physical heat-profile model elucidates how these structural imperfections induce phonon localization, effectively confining heat within individual layers to boost TE efficiency. Finally, we utilize Technology Computer-Aided Design (TCAD) to demonstrate the promising application potential of these novel TE materials in next-generation devices.

Speaker: Shu-Hua Kuo (IHP GmbH Leibniz-Institut für innovative Mikroelektronik)

104 Investigating absorption spectra of fluorescent proteins driven by quantum light

Speaker & Author: Isabella Starflinger

Co-Authors and supervisor: Nikolas Rapp, Dr. Weiyu Zhang and Prof. Dr.
Thomas Pfeifer (Max-Planck-Institut für Kernphysik, Heidelberg)

Description:
This Master thesis lies at the interface of physics and the life sciences and explores whether non-classical properties of light can influence biological processes beyond conventional light–matter interactions. The project is motivated by a recent theoretical prediction of enhanced two-photon absorption in green fluorescent protein (GFP) due to entangled light [1]. We investigate whether the quantum properties of light can affect how fluorescent proteins absorb light and test how entangled photons can change two-photon absorption compared with classical coherent light.
As a light source we use bright squeezed vacuum (BSV) which is an intense quantum state of light with zero mean field and strong photon-number correlations [2]. The BSV at 800 nm is generated via high-gain spontaneous parametric down-conversion in a thick BBO crystal, producing broadband, multimode radiation. As a sample we are exploring fluorescent proteins like mAmetrine or ECFP with a high two-photon absorption rate at the wavelength of the light source. The incident and transmitted BSV spectra are recorded with a multimode spectrometer, from which absorption spectra are extracted. Simultaneously, shot-to-shot photon statistics are measured to capture the BSV's quantum properties.
This project involves developing a measurement setup for protein solutions (microscope slides, capillaries, flow system) and performing absorption measurements under BSV versus classical illumination, testing whether entangled photon pairs measurably alter two-photon absorption efficiency compared to classical light of equal intensity.

References:
[1] Enhancing Two-Photon Absorption of Green Fluorescent Protein by Quantum Entanglement Vl. R. Aslopovsky, A. V. Scherbinin, and A. V. Bochenkova The Journal of Physical Chemistry B 2025 129 (8), 2168-2174
DOI: 10.1021/acs.jpcb.4c07869
[2] Single-shot pulse retrieval of femtosecond bright squeezed vacuum Y. Kern, I. Nisim, M. Birk, A. Rasputnyi, D. Behar, Z. Chen, I. Kaminer, P. Sidorenko, O. Cohen, M. Krüger arXiv, 2025 https://doi.org/10.48550/arXiv.2509.17746

Speaker: Isabella Starflinger (Max-Planck-Institut für Kernphysik, Heidelberg)

105 Investigation of optical losses in the UVC spectral range in AlGaN-based multimode waveguides using photonic integrated circuits and ray tracing simulations

Ultraviolet (UV) photonic integrated circuits (PICs) have many interesting applications, such as biochemical sensing, atomic clocks, and UV Raman spectroscopy. For realizing PICs in the UV spectral range, materials with a large bandgap are required to facilitate low optical losses. One exciting option is AlGaN as it allows the monolithic integration of AlGaN based UV light emitting diodes (UV-LEDs), UV lasers, and photo detectors. However, the optical properties of AlGaN materials, especially the optical losses have not yet been studied in detail in the UV-C spectral range. In this work, the optical losses in 220$\,$μm wide n-Al$_{0.76}$Ga$_{0.24}$N waveguides are determined from LED–detector pairs with waveguide lengths from 400$\,$μm – 1000$\,$μm. The PIC consisting of waveguides, LEDs and photodetectors were fabricated from an AlGaN heterostructure grown by metal-organic vapor phase epitaxy (MOVPE) on sapphire substrates. Our measurements show that the detector signal actually exhibits two different exponential dependencies on the waveguide length with a much smaller slope for waveguide lengths longer than 1000 μm. Monte-Carlo ray tracing simulations showed that scattering at the substrate’s backside can dominate the signal for long waveguide lengths, which we could confirm by applying an absorbing layer on the backside of the sample and measuring the LED-detector pairs again. By ray tracing, we also identified different contributions of the optical losses, namely, the propagation losses and scattering losses. Here, a major challenge is the implementation of the waveguide surface roughness that was measured by atomic force microscopy. In conclusion, we find a total waveguide loss of 30$\,$cm$^{-1}$ to which scattering losses contribute with 6$\,$cm$^{-1}$ and propagation losses with 24$\,$cm$^{-1}$.

Speaker: Verena Kowallik (Technische Universität Berlin)

106 Low dimensional perovskites with controlled orientation and dimensionality for perovskite solar cells

Photovoltaics play a central role in climate change mitigation. Perovskite solar cells are a promising future technology with respect to sustainability and scalability towards the terawatt scale. Current research is focusing on long-term stability and their application in tandem solar cells.
Low dimensional perovskites (LDPs) are being investigated as surface passivation and charge blocking layers for stable perovskite solar cells. LDPs consist of alternating organic cation layers between inorganic perovskite-like slabs. The former are hydrophobic and prevent moisture-induced degradation enhancing the long-term stability. LDPs also show great promise as high-bandgap perovskite photoabsorbers for tandem solar cells. The high bandgap arises from quantum confinement effects rather than from the mixing of halides, thereby minimizing the risk of phase separation. One of the biggest remaining challenges is the control of the orientation and dimensionality n (i.e. thickness of inorganic slabs between the organic cations) of LDPs. Especially low-n LDPs preferably orientate themselves parallel to the substrate, hindering charge transport and limiting the performance of the solar cell.
In this work, we fabricated thin film perovskite samples and characterized them using spectral and spatial photoluminescence, UV-Vis and XRD. We present two approaches for controlling the dimensionality and orientation of LDPs, respectively: By adding lead iodide to the LDP precursor and selecting a poorly-dissolving solvent, it was possible to adjust the stoichiometry and thus the dimensionality of the LDP passivation layer on top of the 3D perovskite substrate.
In pure LPD absorbers with a high bandgap for application in all-perovskite tandem solar cells, the preferred orientation was changed from horizontal to vertical by employing partial halide substitution, which leads to a compressed unit cell and induced crystal growth in the desired direction.

Speaker: Malwine Lühder

107 Method development for quantitative investigation of protein and polysaccharide adsorption on dental materials

Upon exposure to saliva, solid surfaces in the oral cavity are rapidly covered by a bacteria-free pellicle, mainly composed of proteins and polysaccharides. This presents the first step in oral biofilm formation. Despite its importance for subsequent bacterial adhesion, the quantitative contribution of its components remains poorly understood. While protein adsorption has been extensively studied, polysaccharides in mixed biomolecular adsorption layers are difficult to quantify because, spectroscopic signals may overlap and matrix effects complicate component-specific analysis [1,2].
Bovine serum albumin (BSA) and dextran (70 kDa) were used as a simplified model system to investigate simultaneous adsorption on silicon surfaces, which resemble a flat, hydrophilic, oxide-covered surface. For component-specific quantification, direct UV-based determination of BSA in the low UV range was combined with an indirect sulfuric acid-based UV assay for dextran [3]. Ion-exchange chromatography seperated both components prior to quantification, thereby minimizing matrix effects and improving analytical reliability.
The optimized approach was applied to adsorption experiments at different BSA-dextran ratios and pH values. The results were complemented by quartz crystal microbalance measurements and force spectroscopy. The adsorbed-layer composition strongly depended on solution conditions. Both BSA and dextran were detected, with relative contributions varying with pH and mixing ratio.
Together with previous studies on strongly and weakly bound fractions in biomolecular adsorption layers, these findings suggest that BSA-dextran layers contain components with different binding strengths [publication in preparation]. The methodology provides a robust basis for more reliable component-specific quantification of mixed protein-polysaccharid adsorption layers and highlights the relevance of polysaccharides in simplified pellicle-like model systems.

Speaker: Clara Zobeley

108 Natural-Orbital Diagnostics of Optical Excitations Across the SDW-CDW Transition of an Extended Hubbard Chain

We characterize the lowest optically active excitation of a one-dimensional extended Hubbard chain with on-site repulsion $U_0$ and nearest-neighbor repulsion $U_1$. Two complementary natural-orbital diagnostics disentangle the character of the excitation: the one-particle-one-hole (1p1h) weight $W_{1p1h}$, which measures how completely a single particle-hole picture accounts for the transition, and the participation ratio $P_{1p1h}$, which counts the effective number of particle-hole channels contributing to it. A depletion of $W_{1p1h}$ signals beyond-1p1h, strongly correlated physics (2p2h and higher) that a single-excitation description cannot capture, whereas a large $P_{1p1h}$ identifies a collective excitation coherently distributed over many channels while remaining within the 1p1h sector. Mapping both quantities across the $U_0U_1$ plane at half filling, we distinguish regimes of nearly single-particle response, collective-but-1p1h behavior, and genuinely correlated beyond-1p1h excitations, and we resolve how the excitation character changes qualitatively across the $U_0 \simeq 2U_1$ quantum critical point separating the spin-density-wave (SDW) and charge-density-wave (CDW) phases. The natural-orbital framework thus yields a compact, basis-independent map of how competing local and non-local interactions reshape the excitations of a correlated system.

Speaker: Franka Freytag (University of Rostock)

109 Optical Neural Network for MNIST Classification

Artificial intelligence (AI) has become widely adopted across many domains, but
conventional electronic implementations still suffer from high computational cost and
significant energy consumption during inference. Building on previously reported
optical neural networks for MNIST handwritten digit (0–9) classification (X. Lin, Y.
Rivenson et al., 2018), we simplify a diffractive architecture by using a visible laser
wavelength and a spatial light modulator (SLM) to assess its performance and
feasibility under a new optical configuration. The model is trained on a digital
computer, and the learned phase information is then encoded onto the SLM. By
moving to a shorter laser wavelength, we increase the achievable neuron density per
unit area, effectively enlarging the capacity of the optical neural network without
expanding its footprint. By adjusting the freespace propagation distances, we are able
to mimic the connections between neurons in successive layers. In future work, we
plan to extend this visiblewavelength optical neural network from classification tasks
to generative AI, targeting optical image generation on the same platform. This
progression would bridge optical classification and optical generative models, and
help quantify how spectral choices impact the quality, diversity, and energy efficiency
of optical platforms for AI generation.

Speaker: Shou Jou Huang

110 Plasma-enhanced atomic layer deposition of ultra-thin and conformal cobalt nitride catalyst layers

Nina Miller, and Johanna Eichhorn —
Physics Department, School of Natural Sciences, Technical University
of Munich, Am Coulombwall 4, 85748 Garching, Germany

Earth-abundant electrocatalysts—such as transition metal oxyhydroxides and oxides—have emerged as promising and cost-effective alternatives to noble metals for water-splitting applications. To be viable, these electrocatalysts must meet several critical criteria, including long-term chemical stability, adequate electronic conductivity to support efficient charge transfer, and high intrinsic catalytic activity. Recent research has focused on enhancing non-noble metal catalysts through material design and structural engineering. Disordered and porous architectures, in particular, offer improved activity due to a higher density of active sites and larger surface areas compared to crystalline materials. However, these structural advantages often come at the cost of reduced stability under operational conditions, frequently due to electrochemical degradation or insufficient adhesion to the supporting substrate. To address these challenges, strategies focusing on catalyst-support integration and interface engineering have become essential for achieving electrocatalytic layers that are not only highly active but also durable during long-term operation. To move beyond typically applied metal oxyhydroxides and oxides, we apply PE-ALD to grow cobalt nitride catalyst layers. Specifically, we employ Co(iPr-MeAMD)2 as a precursor and systematically explore the impact of deposition parameters on film composition, morphology, and catalytic activity. Reactants, plasma parameters, and substrate temperature are optimized for high Co and low oxygen and carbon content. Interfacing these conformal and ultra-thin catalytic layers with semiconductor light absorbers is a promising strategy to overcome the poor efficiency and material stability of the semiconductor photoelectrodes under harsh photoelectrochemical operating conditions.

Speaker: Nina Miller (Technical University of Munich)

111 Plug-and-Play kHz Laser Control System for Advanced Fluorescence Microscopy

Single-molecule microscopy utilizing alternating laser excitation (ALEX) is an established method for the characterization of biomolecules. However, existing laser control systems are often costly and OEM-specific, limiting flexibility in customized microscopy environments.
To overcome these limitations, we developed an independent, user-friendly laser control approach based on a microcontroller architecture capable of managing up to four individual laser sources. The system is specifically designed for advanced fluorescence microscopy, allowing users to implement preconfigured as well as fully customizable triggering schemes via an intuitive Graphical User Interface (GUI). This enables complex illumination modes such as ALEX for Total Internal Reflection Fluorescence (TIRF) and confocal fluorescence microscopy assays.
The developed solution supports both external hardware triggering and flexible frequency or pulse-width modulation (PWM), achieving pulse durations from 20 µs to 10 s with pulse repetition rates reaching up to 50 kHz. The approach is compatible with any laser source that can be externally modulated via standard TTL signals, providing a highly adaptable and ready-to-use solution for integrated optical systems in the life sciences and beyond

Speaker: Josephine Meitzner

112 PUNCH2.0: Towards a New Level of Reproducibility in Fundamental Physics

PUNCH4NFDI unites Germany's astroparticle, particle, astrophysics, hadron, and nuclear physics communities to collaboratively develop and implement infrastructures that enable FAIR data management across the full research data lifecycle within an integrated digital ecosystem. Over its first funding phase, the consortium established the core building blocks of this ecosystem: the concept of Digital Research Products (DRPs) to capture datasets, software, workflows, and provenance in a reusable form; a Science Data Platform guiding researchers through preparation, retrieval, analysis, and publication; unified authentication via the PUNCH-AAI; and the federated Compute4PUNCH and Storage4PUNCH infrastructure, offering transparent access to heterogeneous HPC, HTC, and cloud resources. Reproducible execution of analysis pipelines is supported through REANA, and first tools and services, such as DRP Hub, have demonstrated the practical feasibility of this approach across PUNCH4NFDI's diverse communities.

Building on these foundations, PUNCH2.0 shifts the consortium's focus towards its users: consolidating and maturing the developments of the first phase, closing the gap between initial implementations and everyday research practice, and actively engaging researchers, students, and other community members in adopting reproducible, FAIR-compliant workflows. This contribution reviews the key outputs of PUNCH1.0 and outlines the strategic priorities for PUNCH2.0, including infrastructure consolidation and community adoption.

This work is supported by the DFG grant "NFDI 39/1" for the PUNCH4NFDI consortium.

Speaker: Victoria Tokareva (Karlsruhe Institute of Technology)

113 Quantized Motion in Two-Dimensional Emitter Arrays

An ensemble of atoms coupled to a common electromagnetic environment displays collective effects, such as sub- and superradiance. These can be harnessed experimentally in cold atom array experiments, where the atoms are tightly confined and close to the motional ground state. This requires to treat atomic motion, both quantum and thermally induced, as a quantum degree of freedom which couples to the internal degrees of freedom of the atoms. Here, we develop a theoretical framework to describe two-dimensional quantized motion in subwavelength atomic arrays within the Lamb-Dicke limit. We derive the Lindblad master equation for a 1D chain of atoms as well as 2D square and ring lattices, demonstrating that this formalism can be readily applied to multiple geometries. In 1D, we show that thermally induced motion results in a change of the exponential decay laws, even for temperatures approaching zero. In 2D, we also study how quantized motion affects the reflectance of an atomic optical mirror, revealing a general dependance on the reduced interatomic distance, dipole moment orientation and detuning. The quantized motion results in a decreased reflectance, while preserving the collective character of the response, as visible from the width of the reflectance spectra and collective Lamb Shift.

Speaker: Siri Raupach (Universität Tübingen)

114 Rapid state-resolved single-atom imaging of alkaline earth fermions

The large ground-state nuclear-spin manifold of fermionic alkaline-earth atoms is an attractive resource for quantum information, thanks to its weak coupling to external perturbations. However, detection schemes that combine fast state-resolved imaging beyond two states with single-atom resolution remain a significant challenge. State-of-the-art quantum simulators with single-particle and spin detection, such as quantum gas microscopes, also suffer from limited state selectivity and long detection times.
In our experiment, we employ the large ground-state nuclear spin manifold of Sr-87 and introduce a detection technique that combines optical Stern-Gerlach separation with high-fidelity ultrafast fluorescence imaging in free space. We achieve state-resolved detection fidelities for up to four states of a single fermionic strontium atom of 93.6-99.7% within 100 microseconds. These results offer a promising perspective for quantum science with multi-electron atoms, including experimental exploration of SU(N) Fermi-Hubbard physics.

Speaker: Sophie Häfele (Universität Hamburg)

115 Setup of a transportable THz-ATR system for liquid investigations

The poster deals with the alignment of a transportable THz-ATR system for the analysis of hazardous liquids. By using an ATR prism, liquids with a high absorption coefficient, such as water, can be investigated. The system uses photoconductive antennas with a high bandwidth of up to 6 THz. The poster describes the alignment of the collimating lenses. Since the expected bandwidth was not achieved with the collimating lenses, the setup was optimized by replacing them with parabolic mirrors. This increased the maximum bandwidth to 3 THz. Further optimization of the focusing lenses and the prism improved the bandwidth of the system. To avoid water vapor absorption lines, an enclosure was built around the setup and nitrogen was supplied. A transportable THz-ATR setup was built and aligned, achieving a THz range up to 3 THz. A comparison with the literature values of Jepsen for the recorded water measurements in the terahertz range showed agreement within the margin of error.

Speaker: Annette Wist (deutsch)

116 Thermalization of optically excited electrons in metals: electron-electron scattering dynamics

When a metal is irradiated with an ultrashort optical laser pulse, the electrons become excited, disturbing the electron distribution into a state far from equilibrium. The subsequent relaxation dynamics determine how the absorbed energy is redistributed within the electronic system and transferred to the lattice, making electron thermalization a key process in ultrafast laser-matter interaction.

In this work, we focus on electron-electron scattering which drives the electrons toward a hot Fermi distribution. We derive the full Boltzmann collision integral in the random-k approximation to calculate the temporal evolution of the electron energy distribution.
Furthermore, we examine to what extent these dynamics can be reproduced by the numerically simpler relaxation-time approach, considering both a constant relaxation time and an energy-dependent relaxation time based on Fermi-liquid theory.

Our results provide insights into the microscopic mechanisms that govern ultrafast thermalization and highlight the advantages and limitations of simplified scattering models.

Speaker: Stephanie Roden (Department of Physics and Research Center OPTIMAS, RPTU University Kaiserslautern-Landau)

117 Towards an all-optical magnetic field quantum sensor based on an ensemble of Tin-vacancy color centers in diamond

Quantum sensing promises new opportunities in applied physics and
life sciences due to high sensitivity, precision, and high spatial resolution.
A possible implementation of a quantum sensor that became well
known in recent years is based on NV centers in diamond. Whereas NV
center based quantum sensors are based on microwave manipulation
of their spin states, the negatively charged group IV-vacancy centers
in diamond offer the option of an all-optical, microwave-free coherent
control of their spin states. This allows for applications where the use
of microwave fields is detrimental or technically challenging.
We here investigate an ensemble of negatively charged Tin-vacancy
(SnV$^{-}$) centers for its suitability for quantum sensing. To this end
we use an experimental implementation based on coherent population
trapping where two spin states are coupled to an excited state via two
laser fields. To detect small magnetic changes we fix the laser frequency
to the steepest slope of the dark-state resonance and detect
the Zeeman shift by a change in the absorption signal. We report
first experimental results on characterising our sample for achievable
sensitivities.

Speaker: Anna Fuchs

Conference Dinner

Wednesday 30 September

Registration

Keynote III (Dr. Maria Azhar)

Convener: Imke Schneider

118 More than Whirls – The Topology of Magnetic Textures

Humans have a natural instinct to characterize objects and sort them into categories. Topology builds on this idea in a particularly unusual way: everyday objects can be classified according to properties that survive continuous deformation. A coffee mug and a doughnut, for example, are topologically equivalent because each has one hole.

Similar ideas have become remarkably powerful in physics. Two-dimensional whirls known as skyrmions have been discovered in a wide range of materials and are now among the best-known examples of topological structures in condensed matter in particular in magnetism.

In three dimensions, vector fields can be even more twisted contain knots and braids. However, it becomes difficult to visualize such fields directly, yet topology allows us to classify them through their global structure.

In this talk, I will show how we can understand magnetic textures by asking whether their underlying field structures contain hidden braids, knots, or links—revealing the beautiful textures nature creates.

Speaker: Maria Azhar (The University of Duisburg-Essen)

09:45 Coffee Break

Scientific Session IX (Invited talk Andrea Bergschneider)

Convener: Louisa Marie Kienesberger (RPTU)

119 Quantum simulation of unconventional pairing with ultracold atoms

Quantum mechanics lies at the heart of many fascinating phenomena in condensed matter physics. One prominent effect is superconductivity, where fermionic electrons pair up to form composite bosons. Their collective quantum coherence gives rise to superconductivity and closely related superfluid behavior.

Ultracold atoms provide a powerful platform for studying these phenomena on a microscopic scale. Fermionic atoms at nanokelvin temperatures mimic electrons on slower timescales and larger length scale. Their interaction strength can be tuned experimentally and the trapping potential can be shaped almost arbitrarily. Imaging techniques allow for local resolution and momentum-resolved measurements. This makes ultracold atoms an ideal platform for quantum simulation of complex many-body systems.

In this talk, I will discuss ultracold fermions in optical lattices, which emulate electrons in a crystal. In these systems, the interplay between interactions and tunneling gives rise to strong correlations that are notoriously difficult to describe theoretically. As a consequence, the pairing mechanism cannot be described by the conventional BCS theory and remains an open question. Using ultracold potassium atoms in optical lattices, we investigate unconventional pairing in the presence of repulsive interactions.

Speaker: Andrea Bergschneider (University of Bonn)

120 Rydberg-Mediated Cooling of a GHz Bulk Acoustic Wave Mechanical Resonator

Rydberg atoms provide electric dipole–allowed transitions that span from optical to microwave frequencies, combining optical control with strong, tunable coupling to microwave-frequency solid-state systems. This makes them a powerful candidate for interfacing atomic ensembles with on-chip electromechanical devices. In this work, we study such an interface between Rydberg atoms and a high-overtone bulk acoustic wave resonator (HBAR), with the objective of cooling a selected mechanical mode close to its quantum ground state.

Our implementation integrates ultracold rubidium atoms with a cryogenic atom-chip platform hosting the HBAR. The atoms are first produced in a magneto-optical trap, then magnetically transferred into a 4 K environment, where they are confined in a superconducting Z-wire trap at a distance of roughly 50 µm from the resonator surface and subsequently excited to Rydberg states.

The atom chip incorporates a coplanar waveguide resonator (CPWR) designed such that its second harmonic is jointly resonant with the targeted Rydberg transition and an acoustic mode of the HBAR. This element is used both to locate and drive the mechanical resonance via microwave fields and to shape the effective interaction landscape experienced by the atoms, thereby influencing the cooling protocol.

We support this architecture with detailed numerical calculations of the electric field distribution and the expected cooling performance of the hybrid system. Our results indicate that efficient dissipation-assisted cooling of the mechanical mode is achievable, enabling significant cooling toward the ground-state regime across realistic parameter ranges. This establishes a realistic route toward atom-mediated control of mechanical quantum systems.

Speaker: Julia Gamper (University of Bonn)

121 Position-Dependent Entanglement-Assisted Quantum Walks with GHZ Coin State

Quantum walks provide a powerful platform for exploring non-classical transport phenomena and for designing controllable quantum dynamics in discrete systems. Here, we investigate the transport properties of a one-dimensional discrete-time quantum walk driven by a three-qubit Greenberger–Horne–Zeilinger (GHZ) entangled coin state, focusing on the contrasting effects of position-dependent (PD) and position-independent (PI) coin operators. The quantum evolution is analyzed under two distinct conditional shift protocols for a range of rotation angles $\theta$, with the resulting dynamics characterized through position-space probability distributions and Shannon entropy. We demonstrate that the combined influence of multipartite coin entanglement, coin rotation, spatial dependence, and the choice of conditional shift operator enables precise control over quantum transport. In the limiting cases $\theta=0$ and $\theta=\pi/2$, the dynamics recover transport regimes analogous to those observed in Bell-state quantum walks, whereas intermediate rotation angles exhibit distinct spreading behaviors ranging from boundary-peaked ballistic transport to enhanced spatial delocalization. The evolution of Shannon entropy provides a quantitative characterization of these transitions, revealing the role of GHZ-induced coherence and interference in shaping the walker dynamics. Our results establish position-dependent operations on multipartite entangled coin states as a versatile approach for controlling transport and localization phenomena in quantum walks, with potential applications in quantum simulation, quantum information processing, and programmable quantum transport systems.

Speaker: Saba Arshad (TU Chemnitz)

122 Dynamics of 40Ca+ Ions Confined in a Tapered Paul Trap

When multiple harmonic oscillators are coupled, they exhibit normal modes, which can be either delocalized or localized. The delocalized modes are used to exchange information between qubits in a Paul trap for quantum information processing, while localized modes can be used for frequency-resolved addressing. In this work, we observe both delocalized and localized normal modes depending on the coupling regime of a tapered Paul trap. We present the radial dynamics of multiple trapped ions, including the radial eigenfrequencies and eigenvectors of two and three calcium ions, studied both theoretically and experimentally [1]. A transition from delocalized to localized radial oscillations was observed as the axial confinement of the trap was decreased. The emergence of the localized modes at lower axial confinements is a direct consequence of the funnel-shaped potential of the tapered ion trap [2]. This behavior is fundamentally different from that of linear ion traps. This work lays the foundation for studying many-body phenomena with trapped ions and for advancing future quantum technologies.

[1] M. Bhardwaj, M. Göb, B. S. Nikolova, B. Bauerhenne, P. A. Ivanov, and K. Singer, “Transition from Collective to Local Radial Motional Modes in a Tapered Paul Trap”, arXiv: 2605.25125 (2026).
[2] B. Deng, M. Göb, M. Masuhr, J. Roßnagel, G. Jacob, D. Wang, and K. Singer, “A comprehensive study on a tapered Paul trap: from design to potential applications”, Quantum Science and Technology 10, 015017 (2024).

Speaker: Manika Bhardwaj (Experimental Physics I, University of Kassel, Heinrich-Plett-Strasse 40, 34132 Kassel, Germany)

Scientific Session X (Invited talk Anja Metelmann)

Convener: Viviane Bauer

123 Dissipation as a Powerful Resource in Engineered Quantum Systems

Engineered quantum systems provide unprecedented opportunities to design, control, and explore quantum phenomena. Platforms such as superconducting circuits and optomechanical systems offer remarkable flexibility in tailoring interactions between electromagnetic and mechanical degrees of freedom, opening new avenues for quantum technologies as well as for fundamental studies of quantum dynamics.
Dissipation, however, is an unavoidable ingredient of any realistic quantum system and is conventionally regarded as detrimental: coupling to an environment leads to loss of coherence and ultimately limits quantum control. This perspective changes when the interaction with the environment itself becomes an object of engineering. Rather than merely suppressing dissipation, one can tailor dissipative processes and exploit them as an active resource for controlling quantum dynamics.
In this talk, I will discuss how deliberately engineered dissipation can give rise to functionality that would be difficult to achieve through coherent interactions alone. I will illustrate how the interplay of coherent dynamics, dissipation, and external driving can be harnessed to steer quantum systems toward desired behavior and generate nontrivial quantum phenomena. These ideas highlight a broader shift in perspective: the environment need not only be an adversary of quantum control, but can become an integral part of the quantum-engineering toolbox.

Speaker: Anja Metelmann (KIT)

124 Deep Neural Networks for generating Path Integral Monte Carlo Configurations

Path Integral Monte Carlo (PIMC) is an exact and powerful framework to describe nuclear quantum mechanical properties of different systems with complex electronic structures at finite temperatures. However, those computations come with a slow convergence rate, also a high variance strongly impacts the accuracy of computed observables.

To overcome those challenges, we introduced a generative neural network, more specifically a Variational Autoencoder (VAE) to enhance sampling efficiency by reproduction and generation of imaginary-time configurations, whereas those configurations shall be consistent with the PIMC statistics. By the use of the VAE, we are able to map the high-dimensional imaginary-time configurations onto a high-dimensional latent space, which contains the underlying statistical structure of the PIMC configurations. From the latent space we can sample and generate new configurations.

By the use of the VAE we are able to enable parallel generation of configurations, also we can integrate symmetry-aware architectures to ensure physical properties like translational or rotational invariance.

Speaker: Zarah Aigner

125 Learning microstructure in active matter

Understanding the full parameter dependence of microscopic structure
in active matter remains a central challenge, particularly for strong activity
and high density, where simulations become increasingly expensive. Here,
we present a data-driven approach that learns radial and angular correla-
tions in terms of the pair-correlation function g$(r,\theta)$ of passive and active
Brownian particles. Our predictions are in close quantitative agreement with
Brownian dynamics simulations, even for parameter values that the neural
networks had not previously encountered during training. Our predictions
are subsequently distilled into compact, closed-form expressions using sym-
bolic regression, providing an interpretable description of the underlying
structure. Our approach offers a unified and computationally efficient route
to understanding non-equilibrium correlations.

Speaker: Writu Dasgupta (TU Darmstadt)

126 Is Device-Independent Certification of Multipartite States Composable Secure?

The goal of quantum key distribution is to establish a secure key between two or more parties. Depending on the exact task, different protocols are available. In the context of multiple parties, for example, we can distribute a common secret key among all participating parties [1]. Another task is to anonymously distribute a key between a subset of parties [2]. Both examples require multipartite entangled states, more precisely GHZ states. It is often assumed that the distribution of the state can be manipulated by an eavesdropper. Therefore, besides distributing a key, the parties would like to ensure that they actually received the assumed states. This can be accomplished if all parties have access to some measurement devices. State certification protocols are provided for different levels of assumptions. In the scenario where the measurement devices are well characterised, the GHZ state can be verified using the protocol presented in Ref. [3]. Also for the more secure device-independent (DI) scenario, where no assumptions are made about the quantum states or the working behaviour of the devices, the state can be certified [4].

Proving that a protocol, such as state certification or key distribution, is secure is already a demanding task. Most protocols are proven to be 'standalone secure'. However, this does not imply that the protocol remains secure when used as a subroutine for more complex tasks. A protocol is 'composable secure' if it can be used securely as a building block in any application. Since proving that a protocol is composable secure is even more challenging, only a few security proofs meet this standard. We aim to prove that DI state certification of multipartite states [4] is composable secure, even in the presence of dishonest parties. I will present intermediate results in my talk.

[1] Cabello, arXiv:quant-ph/0009025 (2000)
[2] Grasselli, PRX Quantum 3, 040306 (2022)
[3] Pappa, PRL 108, 260502 (2012)
[4] Murta, PRL 131, 140201 (2023)

Speaker: Lina Vandré (neQxt, TU Wien)

Scientific Session XI (Invited talk Giovanna Morigi)

Convener: Larissa Schwarz

127 Search as quantum selforganized process

Efficient retrieval of information is a core operation in the world wide web, is essential for the sustainance of living organism, and is a paradigm for optimization algorithms. Inspired by the food search dynamics of living organisms, we discuss a search on a graph where the dynamics is a selforganized process resulting from the interplay of coherent dynamics and noise. We show that noise can be beneficial to the search dynamics leading to significantly faster convergence to the optimal solution.

Speaker: Giovanna Morigi (Saarland University)

128 How Quantum Information Excites Chemists: Optimizing Excited State Orbitals with Tools from Quantum Information Theory

Accurately computing the electronic energy of molecular reactants and during chemical reactions is the central challenge of quantum chemistry. Unlike mean-field methods such as Hartree-Fock or Kohn-Sham density functional theory, configuration interaction (CI) methods exactly calculate the repulsive interaction between electrons based on a many-particle wave function rather than relying on approximate functionals. This leads to a systematically improvable accuracy, but also requires far greater computational resources and becomes increasingly intractable for large molecules. Complete Active Space (CAS) methods mitigate this computational cost by restricting the full configuration interaction (FCI) calculation to a subset of orbitals (the active space) while keeping the occupation of the remaining (nonactive) ones fixed. This simplification inevitably introduces an error depending on the quality of the involved orbitals, but it was shown that this error can be minimised by an algorithm based on quantum information: minimizing the entanglement of the nonactive orbitals also leads to a minimization of the resulting CAS ground-state energy. This method is called Quantum Information-Assisted Complete Active Space Optimization (QICAS).
QICAS has previously only been formulated and tested for calculations on electronic ground states. Due to the high relevance of excited states in most subfields of chemistry including catalysis, photonic materials, and spectroscopy, and their more complex electronic structures, there is a significant demand for their reliable and efficient computational modeling. Motivated by this, we extended QICAS to target excited states (and ensembles thereof) as well. We present a newly developed quantum information cost function based on the ensemble variational principle and discuss that without its invocation, the QICAS cost function loses its validity as a proxy for active-space quality.

Speaker: Emma Woerz (TUM/LMU)

129 Pulse Engineering via Projection of Response Functions at Infinite Nonlinear Order

Quantum computers promise new ways of solving problems that are difficult for classical computers, but their practical realization requires extremely precise control of quantum systems. In this talk, I will introduce the general challenge of controlling quantum devices and explain why reliable quantum operations are essential for scalable quantum computing. I will then present a new approach for quantum optimal control that iteratively improves control parameters by evaluating how the implemented operation responds to applied control fields¹. Compared to conventional optimization strategies, the method avoids the need for hyperparameter tuning, making it more practical and accessible for real-world applications. Using the example of multi-qubit gate optimization, I will give an overview of how such control methods can help improve the fidelity and robustness of quantum operations.

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¹Kley, L. and Mathey, L., “Pulse engineering via projection of response functions at infinite nonlinear order”, arXiv:2607.24725, 2026. doi:10.48550/arXiv.2607.24725.

Speaker: Lia Kley (Uni Hamburg, ZOQ)

130 Decoherence and Quantum Darwinism in a Scattering Model

In the quantum computation era, the need of controlling the coherence lifetime of open quantum systems has increased considerably, making decoherence a critical topic. Quantum Darwinism (QD), a concept popularized by W. Zurek [1], can be viewed as a special case of decoherence with unique characteristics and can shed some light on the quantum-to-classical transition. In this scenario, nearly all classical information available about a system is spread redundantly in
small fragments of a reservoir-like environment. However, although one can find experiments reporting direct tests of QD [2-4], it is still a challenge to make experimental realizations in more realistic setups. To address this, we studied different scenarios of a model where the system-environment interaction happens via quantum scattering subject to a potential with the Fermi-Huang pseudo-potential [5,6] form. In this talk I will briefly introduce the main concepts, and present the results we could reach and how they could help make more realistic experimental
setups feasible.

References
[1] Zurek, Wojciech, Nature physics 5.3 (2009)
[2] M. A. Ciampini, G. Pinna, P. Mataloni, and M. Paternostro, Phys. Rev. A 98, 020101(2018).
[3] M.-C. Chen, H.-S. Zhong, Y. Li, D. Wu, X.-L. Wang, L. Li, N.-L. Liu, C.-Y. Lu, and J.-W.Pan, Sci. Bull. 64, 580 (2019).
[4] T. Unden, D. Louzon, M. Zwolak, W. H. Zurek, and F. Jelezko, Phys. Rev. Lett. 123,140402 (2019).
[5] E. Fermi, Ricerca Sci. 7, 13 (1936).
[6] K. Huang and C. N. Yang, Phys. Rev. 105, 767 (1957).

Speaker: Sheilla Marques (RPTU)

11:40 Break

Gründerinnenpanel: Female Founders Panel

131 Founders Panel

In this panel we want to highlight young female founders and encourage you for this exciting career path.
The panel will be moderated by Claus Roll (OPTICA) und Serina Almassu (EPS Young Minds).
Confirmed panelist include:
Monica Arenas (Trace Crystal, Luxemburg) und Qiaoshuang Zhang (Rheoo GmbH, Karlsruhe)

12:50 Lunch

Physics@Work III

Convener: Katerina Kanevche (RPTU - Kaiserslautern)

132 Encouraging Female Scienepreneurs in Deep-Tech – TUM Venture Lab Quantum / Semicon

This talk explores entrepreneurship as a viable and rewarding career path for women in physics — one that's often underrepresented in traditional academic career narratives. Drawing on experience in quantum technology venture building , the talk will help attendees think about their own PhD work through a commercial lens: how to recognize when their research might have real-world applications, what questions to ask about market relevance, and how technical expertise built during a PhD can translate into founding a company. The session aims to demystify the transition from academia to entrepreneurship and encourage more women physicists to see their PhD work as a potential foundation for a startup & not just a dissertation.

Speaker: Gargi Kodgirwar (TUM Venture Lab Quantum / Semicon)

Scientific Session XII (Invited talk Zlata Fedorova)

Convener: Sabrina Hammel (RPTU Kaiserslautern)

133 Valleytronics meets nanophotonics: from fundamental light–matter interactions to scalable photonic platforms

Two-dimensional transition-metal dichalcogenides (TMDs) are atomically thin semiconductors that exhibit strong excitonic effects, high optical nonlinearities, and valley-contrasting optical selection rules. In monolayer TMDs, circularly polarized light selectively addresses the inequivalent K and K′ valleys, enabling optical initialization and readout of the valley degree of freedom. These unique properties, combined with their intrinsically planar geometry, make TMDs an attractive platform for valleytronics and their integration with nanophotonic architectures.
In this talk, I will present our recent work on hybrid TMD-nanophotonic systems, where valley-polarized excitons interact with resonant dielectric and plasmonic nanostructures. I will show how engineered optical environments can modify emission properties and enable control over the valley degree of freedom, ranging from enhanced and redirected valley-polarized photoluminescence to the manipulation of spin-valley excitations with structured light. I will further discuss hybrid platforms operating from the weak- to the strong-coupling regime, highlighting how nanophotonic design enables new opportunities for tailoring exciton-photon interactions and creating valley-dependent hybrid light-matter states. Finally, I will outline prospects for scalable valleytronic and quantum-photonic technologies based on 2D semiconductors, including integrated quantum light sources, active metasurfaces, and on-chip photonic architectures.

Speaker: Zlata Fedorova (Friedrich-Schiller-Universität Jena)

134 Distortion-driven bond strength in IV-VI chalcogenides and LaSb

Binary group IV-VI chalcogenides, like SnTe, GeTe and SnSe, are of great scientific interest due to their diverse possible applications ranging from thermoelectrica to phase change memory. As possible origin of these remarkable properties, the interatomic bonding is center of an ongoing scientific debate. All binary group IV-VI compounds exhibit an average number of five valence electrons per lattice site similar to elemental Sb. The crystal structures differ for the different compounds: whereas SnTe exhibits a cubic rocksalt structure, GeTe and SnSe have a rhombohedral or orthorhombic structure, respectively. The crystal structure of both GeTe and SnSe could either be viewed as layered structure or as distorted cubic structure, which would be associated with either (polar-)covalent or multicenter bonding. LaSb exhibits an ideal cubic rocksalt structure, like SnTe, but has four valence electrons per lattice site on average. Therefore, it is an ideal material for comparison of bonding characteristics with SnTe. To study the bonding characteristics of the IV-VI chalcogenides SnTe, GeTe and SnSe as well as LaSb, extended X-ray absorption fine structure spectroscopy (EXAFS) was performed at the respective pnictogen and chalcogen K-edges at ten different temperatures ranging from 10 K to 295 K at beamline P65 of PETRA III at DESY in Hamburg. Interatomic force constants up to the 4$^{th}$ nearest neighbor were extracted from the temperature dependence of the mean square relative displacement $\sigma^2$ using a correlated Einstein model. The behavior of the force constants with increasing interatomic distance is compared for the IV-VI compounds and LaSb and to other experimental and theoretical force constants reported in the literature. In relation with the distortion of the crystal structure this contributes to the fundamental understanding of the bonding characteristics in IV-VI compounds as potential origin of their remarkable properties.

Speaker: Franziska Zahn (Felix Bloch Institute for Solid State Physics, Leipzig University)

135 Directional Transport in a Plasmonic Ratchet Induced by Tailored Dissipation

We present a joint experimental and theoretical study of a ratchet implemented in arrays of evanescently coupled plasmonic waveguides with tailored losses. In this setup the time-periodic dissipation is the only active mechanism and notably, we find better rectified transport and lower losses in the transmitted signal with increased local dissipation. Using Floquet theory, we uncover a driving regime that allows efficient directional transport for suitable driving frequencies and loss rates, which are linked to linear quasienergy bands with minimal losses. These regions are separated from non-resonant behavior by sharp transitions with characteristic exceptional points in the spectrum. Direct experimental observation of the Floquet-dissipative ratchet effect using a combination of real- and Fourier-space leakage radiation microscopy is provided.

Speaker: Anna Sidorenko (Physikalisches Institut, University of Bonn)

Scientific Session XIII (Invited talk Iris Niehues)

Convener: Emily Kruel

136 Multispectral near-field studies of boron nitride micro- and nanostructures

Scattering-type scanning near-field optical microscopy (s-SNOM) and nanoscale infrared point spectroscopy (nano-FTIR) are powerful techniques for nanoscale optical mapping of various material properties. Both rely on elastic light scattering from an atomic force microscope tip illuminated by either monochromatic or broadband laser light. This metallic tip acts as an optical antenna, concentrating the illuminating field into a highly localized near field at its apex. By interferometrically recording the light scattered by the tip as it scans across the sample, s-SNOM generates near-field amplitude and phase images – revealing information about the local dielectric function when using monochromatic laser illumination. Alternatively, Fourier-transform spectroscopy of the tip-scattered field (using IR broadband illumination) enables nano-FTIR spectroscopy [1,2]. Beyond elastic scattering, the near-field microscope can detect inelastically scattered light, including techniques like tip-enhanced Raman spectroscopy and photoluminescence spectroscopy.
We utilize our s-SNOM setup to investigate the nanoscale optical properties of boron nitride (BN). In my talk I will focus on two different excitations in BN:
1. Phonon polaritons in BN layers: s-SNOM is widely used to generate and study phonon polaritons in hexagonal BN (hBN). While most works focus on exfoliated flakes, I will present new results on MOVPE grown hBN crystals. In contrast to previous studies, we observe clean polariton fringes only with a higher damping rate, i.e., a shorter propagation length, compared to their counterparts in exfoliated hBN. In addition, we demonstrate phonon polariton confinement in MOVPE grown isotopically pure BN micro-triangles and fully characterized the confined modes in these structures by s-SNOM and nano-FTIR measurements.
2. Color centers in hBN: These single-photon emitters (SPEs) represent an exciting system, as they provide stable and bright single-photon emission even at room temperature. We employ the near-field optical microscope, to detect PL signals in the visible spectral range influenced by the presence of the metallic tip (TAPL) and the near-field nanofocus (TEPL) [3].

References
[1] N. Ocelic, et al., Appl. Phys. Lett. 89, 101124 (2006).
[2] M. Schnell, et al., Nat. Commun. 5, 349 (2014).
[3] I. Niehues et al., Nanophotonics 14(3), 335-342 (2025).

Speaker: Iris Niehues (University of Münster)

137 MBE-grown Germanium Heterostructures as a Platform for Superconducting Quantum Devices

Hybrid superconductor-semiconductor devices are of interest for various applications in quantum physics – they can host different types of qubits or can be used for compact, low-noise, cryogenic electronics elements such as parametric amplifiers [1]. As semiconductor, we employ strained germanium quantum wells embedded in planar silicon-germanium heterostructures. Germanium was shown to be a suitable platform for spin qubit applications due to its small effective mass, suppressed hyperfine interaction, and high mobility [2]. Due to the proximity effect, germanium inherits superconducting properties when contacted by a superconductor and is thus also a promising host for superconducting spin qubits.

Aiming at a pristine super-semi interface, we developed a complete hybrid super-semi heterostructure stack, with an in-situ grown superconducting film of aluminum on top of the semiconductor. We characterise four different hybrid super/semi heterostructure stacks in terms of their structural, transport and microwave [3] properties, enabling a choice of a suitable heterostructure design for specific future applications.

References
1. Phan, D. et al. Gate-Tunable Superconductor-Semiconductor Parametric Amplifier.
Physical Review Applied 19, 064032 (June 9, 2023).
2. Nigro, A. et al. Demonstration of Microwave Resonators and Double Quantum Dots on
Optimized Reverse-Graded Ge/SiGe Heterostructures. ACS Applied Electronic Materials 6,
5094–5100 (June 26, 2024).
3. Ruggiero, L. et al. High-Quality and Field Resilient Microwave Resonators on Ge Quantum
Well Heterostructures. npj Quantum Information 12, 118 (June 11, 2026).

Speaker: Vera Jo Weibel (Department of Physics, University of Basel)

14:30 Break

15:00 Break

Labtours (registration onsite)

17:30 Break

Public Talk (Prof. Dr. Sibylle Günter)

Convener: Baerbel Rethfeld (Department of Physics and Research Center OPTIMAS, RPTU University Kaiserslautern-Landau)

138 Fusionsenergie – Die Sonne auf die Erde holen?

Prof. Dr. Sibylle Günter,
Max-Planck-Institut für Plasmaphysik Garching und Greifswald

Der nahezu unbegrenzte, weltweit verfügbare Brennstoff sowie seine äußerst günstigen Sicherheitseigenschaften machen die Kernfusion zu einer äußerst attraktiven Alternative zur Kernspaltung. Dank ihres vergleichsweise geringen Flächenbedarfs eignet sie sich besonders für die Energieversorgung von Megacities und energieintensiver Großindustrie.
Für die Fusion muss Materie auf Temperaturen von über 100 Millionen Grad erhitzt werden – etwa zehnmal heißer als das Innere der Sonne. Unter diesen Bedingungen liegt die Materie als vollständig ionisiertes Plasma vor. Die geladenen Teilchen können mithilfe starker Magnetfelder eingeschlossen werden, die zugleich die notwendige Wärmeisolierung sicherstellen.
Für den magnetischen Einschluss haben sich zwei Konzepte als besonders vielversprechend herauskristallisiert: Tokamak und Stellarator. Das Tokamak-Konzept, das im internationalen Großprojekt ITER in Cadarache (Südfrankreich) umgesetzt wird und zu dessen Vorbereitung der Tokamak ASDEX Upgrade am IPP in Garching wesentlich beiträgt, gilt derzeit als die technologisch am weitesten entwickelte Einschlusskonfiguration. Allerdings erfordert der Tokamak einen kontinuierlichen Stromfluss im ringförmigen Plasma, was einen dauerhaft stationären Betrieb erheblich erschwert.
Eine Alternative dazu ist der Stellarator. Er besitzt eine deutlich komplexere Magnetfeldgeometrie, ermöglicht jedoch von Natur aus einen stationären Betrieb. Die besondere Herausforderung besteht darin, die komplexe Magnetfeldstruktur so zu optimieren, dass ausreichend gute Plasmaeinschlusseigenschaften erreicht werden.
Mit Wendelstein 7-X in Greifswald wurde erstmals ein optimierter Stellarator realisiert, der groß genug ist, um das Kraftwerkspotenzial dieses Konzepts experimentell zu demonstrieren. Bereits in den ersten Experimentierkampagnen konnte die erfolgreiche Optimierung der Magnetfeldstruktur nachgewiesen werden. Damit eröffnet der Stellarator die Perspektive auf besonders effiziente und wirtschaftliche Fusionskraftwerke der Zukunft.

Speaker: Sibylle Günter (Max Planck Institute for Plasma Physics Greifswald)