Speaker
Description
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)
