Microwave-optical transduction with integrated gallium phosphide devices

Optomechanical resonators provide a route to interconversion of microwave and optical photons for quantum interconnects. We present a platform comprising a GaP photonic crystal cavity integrated on prefabricated niobium circuits, with mechanical modes at ~3.2 GHz and optomechanical coupling rates up to g0/2π ≈ 300 kHz.