Noise performance of a high-throughput microwave-optical transducer in upconversion and downconversion (Part 1)

A transducer bridging microwave and optical frequencies with sufficiently low noise would allow the deterministic generation of arbitrary optical quantum states and the networking of remote superconducting quantum processors. Here we present bidirectional measurements quantifying the performance of a membrane-based opto-electromechanical transducer operating at bandwidths that are compatible with state-of-the art superconducting qubit lifetimes. Continuous operation of our high-efficiency transducer at tens-of-kHz transduction bandwidths allows for high total transduction rates. By careful selection of a more limited bandwidth over which to constrain a potential signal, our device achieves input-referred added noise densities approaching single-photon levels in both upconversion and downconversion. These measurements elevate this platform as a compelling candidate for quantum transduction applications, with planned improvements to its noise performance.