A Lithium Niobate Electro-Optic Transducer for Quantum Networks

In order to create a quantum network in which superconducting qubit processors are connected over kilometer-scale distances, transducers capable of converting quantum information between microwave and optical frequencies are required to allow for fiber optical networking. We present the design and experimental demonstration of an electro-optic photon converter to connect superconducting qubit-based systems with light. We fabricate lithium niobate racetrack resonators with superconducting circuits and demonstrate microwave-to-optical photon coupling rates over 1.5 kHz at cryogenic temperatures. We characterize our transducer with resolved sideband spectroscopy to measure the electro-optically generated Stokes and anti-Stokes optical sidebands which show an extinction ratio of ~30 dB.