Continuous microwave-to-optical quantum transduction via silicon nanomechanics

A microwave-optical quantum interface is required for distributed quantum information processing using superconducting qubits. In order to entangle distant quantum processors, a microwave-to-optical transducer must operate with high efficiency, large bandwidth, and less than one photon of input-referred added noise. Here, we meet these requirements in an integrated electro-optomechanical device that utilizes electrostatic coupling between high-impedance microwave resonators and crystalline silicon nanomechanical oscillators. By leveraging the small acoustic loss and low optical absorption heating of silicon, we demonstrate continuous quantum-enabled microwave-to-optical conversion with an external efficiency of 2.20 ± 0.06%, bandwidth of 88.9 ± 2.1 kHz, and an input-referred added noise of 0.94 ± 0.03. With further improved noise performance, our device presents a realistic path towards high rate entanglement of remote superconducting qubits.