Characterization of an on-chip microwave to optical transducer using ytterbium-doped crystals*

Microwave to optical transduction is essential for large-scale quantum networks and distributed quantum computing with superconducting quantum systems. Ensembles of rare-earth ions (REI) coupled to resonators are one of the promising systems for developing quantum transducers because of their ability to transfer a quantum state between electronic spin, nuclear spin and optical transitions. Among the REI, ytterbium is of special interest because of its simple hyperfine level structure, strong dipole moment, and narrow inhomogeneities in both optical and spin domains.

Here, we present the current progress of an on-chip ytterbium-based microwave to optical transducer. The optical structure is fabricated via focused-ion beam ensuring good overlap between the ions and the optical mode. The superconducting microwave resonator is patterned from niobium by surrounding the optical structure, thus ensuring good mode overlap of the microwave and optical modes. We characterize the transducer performance at temperatures below 500mK.

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, Co-design Center for Quantum Advantage (contract number DE-SC0012704)