Studies of NbN high-impedance superconducting microwave resonators under optical illumination for quantum transduction applications*

Quantum microwave to optical transduction is an emerging technology for integrating microwave superconducting quantum circuits into large scale quantum networks. Combining superconducting circuits and optical devices in a chip-scale transducer is a key challenge due to disruption of the superconducting phase under optical illumination. Motivated by this challenge, we have developed high-Q (105 at single-photon-level), tunable, GHz-frequency niobium nitride (NbN) resonators on silicon-on-insulator for integration into a piezo-acoustic transducer. Our geometry comprises meandered loops, which allows for high impedance and 10% frequency tuning via kinetic inductance. Upon illumination with a lensed fiber parallel to the device, we observe resonator frequency shifts within the intrinsic linewidth for up to 250 μW of continuous wave laser power at 1.55 μm. Further, with pulsed illumination, we observe measurement-limited recovery on the microsecond timescale. With this, we expect 10 KHz repetition rate in pulsed mode operation, a 100x improvement compared with our previous aluminum-based transducer.