Toward on-chip microwave to optical transduction using erbium doped crystals

Future quantum networks based on superconducting circuits that operate at microwave frequencies will strongly benefit from optical interconnects between the distant nodes. One promising platform to achieve bidirectional conversion between microwave and optical photons are ensembles of rare-earth ions (REIs) strongly coupled simultaneously to an optical and a microwave resonator. The strong interactions between the REIs and photons are critical to minimize the optical power required to mediate the conversion process and for potential operation at temperatures below 100 mK.
Here, we present our progress towards a REI-based transducer using superconducting microwave resonators and amorphous silicon photonic crystal resonators patterned on the surface of an erbium-doped yttrium orthovanadate crystal. Both resonators are designed to maintain high quality factors while preserving the mode overlap between the optical and microwave fields required for high conversion efficiency. We present initial results characterizing the device performance at cryogenic temperatures.