Talk: Multimode microwave-to-optical transduction with high-overtone bulk acoustic resonators

Organizer:
Lehrstuhl für Experimentalphysik (Eichler)

Speaker:
Benjamin Neubauer

Title:
Multimode microwave-to-optical transduction with high-overtone bulk acoustic resonators

Abstract:
A major challenge in realizing distributed quantum networks is linking superconducting circuits to optical fibers. Quantum transducers bridging microwave and optical frequencies are an essential building block in this effort. Their operation requires an efficient nonlinear interaction to mediate frequency conversion of single quanta with near-unity efficiency. In this talk, I will present a transducer design developed in the Hybrid Quantum Systems Group at ETH Zurich that employs a high-overtone bulk acoustic resonator (HBAR) as an intermediary oscillator. The HBAR couples to superconducting circuits via piezoelectric interactions and to laser light via optomechanical Brillouin scattering, enabling full microwave-to-optical transduction. A characteristic of this design is that the frequency spacing between acoustic eigenmodes of the HBAR is smaller than the transducer bandwidth, so that multiple acoustic modes participate in the transduction process. During my Master's thesis I worked on engineering the acoustic mode spectrum through geometry simulations to maximize the transduction efficiency. In addition, I performed electromechanical measurements on device prototypes to characterize acoustic mode lifetimes and electromechanical coupling strengths.