Microwave to optical quantum conversion

Microwave and optical photons are two principle carriers for quantum information. Microwave photons can be effectively manipulated by superconducting circuits at milli-Kelvin environments; optical photons transmit information over long distances in optical fibers. Therefore, microwave-to-optical (MO) quantum converters, which interface superconducting qubits and optical photons, represent an indispensable component in future quantum networks. Here, we present our recent efforts on developing integrated gigahertz piezo-optomechanics and electro-optics (EO) MO converters. We demonstrate efficient bi-directional conversion in both schemes at cryogenic temperatures. Moreover, we realized MO conversion with the device in the quantum ground state, while achieving efficient conversion efficiency. Our results represent a substantial step towards faithful microwave to optical quantum conversions.