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 Qi>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.
@article{arxiv.1507.05126,
title = {Frequency-tunable Superconducting Resonators via Nonlinear Kinetic Inductance},
author = {Michael R. Vissers and Johannes Hubmayr and Martin Sandberg and Saptarshi Chaudhuri and Clint Bockstiegel and Jiansong Gao},
journal= {arXiv preprint arXiv:1507.05126},
year = {2015}
}