Recent advances towards quantum operation of a microwave-mechanical-optical transducer

Future long-distance quantum networks based on local computational nodes of superconducting qubits connected by optical fibers will require a bidirectional, quantum-coherent transducer between microwave and optical frequencies. A converter can be realized by simultaneously coupling a MHz frequency mode of a SiN membrane to a superconducting LC circuit and an optical Fabry-Perot Cavity. We demonstrated such a converter in 2018 with 47% efficiency and 38 photons of added noise [1]. Significant contributions to this added noise come from the membrane thermal motion and fluctuation of the LC circuit parameters. Here, we present a new electromechanical circuit design that reduces the added noise by improving sideband cooling of the membrane.

[1] Higginbotham, A. P., et. al. “Harnessing electro-optic correlations in an efficient mechanical converter,” Nature Physics 14, 1038-1042 (2018)