Efficiency and noise characterization of an on-chip microwave to optical transducer using ¹⁷¹Yb³⁺: YVO₄ crystals

Microwave-to-optical transduction is essential for large-scale quantum networks and distributed quantum computing based on superconducting qubits. Rare-earth ion (REI) ensemble is one of the promising systems because of the narrow inhomogeneous linewidth in both optical and spin domain at cryogenic temperature, which provides strong nonlinearities for facilitating the interaction between microwave and optical fields. Ytterbium-171 is of special interest because of its strong dipole moment and simplest hyperfine structure.

Here, we present our on-going efforts on an on-chip REI-based microwave to optical transducer using ¹⁷¹Yb³⁺: YVO₄, with integrated superconducting microwave resonators and gold reflectors. The microwave resonator was fabricated out of niobium on top of ¹⁷¹Yb³⁺: YVO₄ substrate. A thin layer of gold was evaporated on the back of the chip for light collection. We characterized the transducer performance at dilution temperature. Strong coupling between the resonator and excited state spin was observed. We calibrated efficiencies in both continuous-wave mode and pulsed mode. The added noise during pulsed operations was measured on a single photon detector. We’ll discuss the future directions as well in the presentation.

The authors acknowledge support from Office of Naval Research Award No. N00014-22-1-2422 and U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Codesign Center for Quantum Advantage (contract number DE-SC0012704).