Two-dimensional optomechanical crystals for microwave-to-optical quantum transduction

Piezo-optomechanical transducers are a promising platform for interfacing quantum signals between microwave and optical frequencies. Current state-of-the-art devices utilize optomechanical crystals based on one-dimensional (1D) nanobeam geometries, however the noise performance of such devices is ultimately limited by optical absorption heating induced by the laser pump used to mediate transduction. This parasitic heating limits operation to a low efficiency regime at reduced optical pump powers. Parallel experiments using two-dimensional (2D) optomechanical crystals with increased thermal contact to the cold bath have shown significant improvements in noise-efficiency metrics compared to 1D devices. We present the design and characterization of a transducer incorporating a 2D piezo-optomechanical crystal. These devices have the potential to break the efficiency-noise tradeoff inherent to 1D nanobeam geometries, opening a path towards integration of superconducting quantum processors with optical networks.