Abstract: Coherent microwave-optical photon conversion is pivotal in the development of scalable quantum networks, which incorporate powerful local microwave quantum processors, such as superconducting qubits, with long-distance quantum channels through optical fibers. However, due to the dramatic mismatch in frequency and wavelength, establishing effective coupling between microwave and optical photons remains a challenging task.

In this talk, I will demonstrate an efficient superconducting piezo-optomechanical interface where the microwave-optical interaction is mediated and significantly enhanced by high-frequency phonons. Moreover, the implementation of high-frequency mechanics can greatly suppress added thermal noise, paving the way for quantum operation.

I will first introduce high-frequency piezo-optomechanical resonators above 10 GHz, next demonstrate multimode strong coupling in superconducting electromechanics, and then integrate the two systems together and present our most recent progress on bidirectional coherent microwave-optical photon conversion.

Finally, two promising future directions will be discussed. One is entanglement-based microwave-optical quantum transduction, which will be able to bypass the stringent requirements for direct conversion. The other one is the exploration of nonlinear micro-electromechanical system (MEMS) in the quantum regime for novel applications such as quantum memory.