Towards microwave-to-optical transduction using Fermilab's high quality factor microwave cavities

An efficient quantum transducer that faithfully and reversibly converts optical quantum signals to microwave quantum signals could be used as an interface between superconducting-based quantum devices, such as transmon qubits, and optical photons. Despite the great potential for quantum sensors and heterogeneous quantum networks, and many theoretical studies dedicated to transduction protocols, there are relatively few demonstrations of microwave-to-optical transduction at the quantum level. Most demonstrations have demonstrate either low conversion efficiency or high noise, and thus are not suitable for quantum signals. One way to improve the efficiency of a transducer is to use high quality factor (Q) microwave cavities. Fermilab has developed bulk Nb superconducting cavities with record-high 2 second photon lifetime (Q=1011), a significant improvement compared to previous efforts. We will present preliminary studies and solutions to determine an optimum transducer design for these cavities.