Frequency-tunable Superconducting Resonators via Nonlinear Kinetic Inductance

TL;DR

This paper presents a superconducting resonator with a tunable frequency range of 180 MHz around 4.5 GHz, maintaining high quality, useful for quantum computing, superconductor studies, and sensor readout.

Contribution

It introduces a frequency-tunable high-Q superconducting resonator using nonlinear kinetic inductance controlled by DC current injection.

Findings

Achieved continuous frequency tuning of 180 MHz

Maintained high internal quality factor Q_i > 180,000

Demonstrated potential applications in quantum computing and superconductor measurement

Abstract

We have designed, fabricated and tested a frequency-tunable high-Q superconducting resonator made from a niobium titanium nitride film. The frequency tunability is achieved by injecting a DC current through a current-directing circuit into the nonlinear inductor whose kinetic inductance is current-dependent. We have demonstrated continuous tuning of the resonance frequency in a 180 MHz frequency range around 4.5 GHz while maintaining the high internal quality factor $Q_i> 180,000$. This device may serve as a tunable filter and find applications in superconducting quantum computing and measurement. It also provides a useful tool to study the nonlinear response of a superconductor. In addition, it may be developed into techniques for measurement of the complex impedance of a superconductor at its transition temperature and for readout of transition-edge sensors.