Nonlinear WSi Nanowire Constrictions in Superconducting Quantum Circuits

Kinetic inductance materials have been used to provide high inductance and nonlinearity while maintaining a small device footprint in superconducting devices such as detectors, amplifiers and other inductive elements. Inclusion of these nanowires in superconducting qubits has the potential to provide new nonlinear elements such as weak link junctions or quantum phase slip elements. In this talk, we explore the nonlinear behavior of nanowire constrictions fabricated from tungsten silicide (WSi), an amorphous high kinetic inductance material. We study various devices including RF-SQUIDs with different nanowire geometries. We report on the current phase relationship of these WSi constrictions and their potential to expand the toolbox of superconducting qubits.