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Description
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.
