Linear and Nonlinear Properties of a Compact HighKineticInductance WSi Multimode Resonator
Abstract
The kinetic inductance (KI) of superconducting devices can be exploited for reducing the footprint of linear elements as well as for introducing nonlinearity to the circuit. We characterize the linear and nonlinear properties of a multimode resonator fabricated from amorphous tungsten silicide (WSi ), with a fundamental frequency of f_{1}=172 MHz. We show how the multimode structure of the device can be used to extract the different quality factors and to aid the nonlinear characterization. In the linear regime, the footprint is reduced by a factor of approximately 2.9 with standard lateral dimensions, with no significant degradation of the internal quality factor compared to a similar Al device. In the nonlinear regime, we observe selfpositive frequency shifts at low powers, which can be attributed to saturation of tunneling twolevel systems. The crossmode nonlinearities are described well by a Kerr model with a selfKerr coefficient on the order of  K_{11} /2 π ≈1.5 ×10^{−7} Hz per photon. These properties, together with a reproducible fabrication process, make WSi a promising candidate for creating linear and nonlinear circuit quantum electrodynamics elements.
 Publication:

Physical Review Applied
 Pub Date:
 October 2021
 DOI:
 10.1103/PhysRevApplied.16.044017
 arXiv:
 arXiv:2107.13264
 Bibcode:
 2021PhRvP..16d4017K
 Keywords:

 Condensed Matter  Superconductivity;
 Physics  Applied Physics
 EPrint:
 7pages, 5 figures (+supplementary with 4 pages and 2 figures)