Tunable superconducting nanoinductors

TL;DR

This paper investigates the properties of superconducting nanowire inductors made from niobium and niobium nitride, focusing on their inductance, temperature, and current dependence, with potential applications in microwave circuits.

Contribution

It provides detailed characterization and modeling of ultra-thin superconducting nanowire inductors, highlighting their tunability and suitability for microwave superconducting circuits.

Findings

Kinetic inductance scales linearly with nanowire length

Measured inductance values are 1 nH/um for NbN and 44 pH/um for Nb

Temperature and current dependence match theoretical predictions

Abstract

We characterize inductors fabricated from ultra-thin, approximately 100 nm wide strips of niobium (Nb) and niobium nitride (NbN). These nanowires have a large kinetic inductance in the superconducting state. The kinetic inductance scales linearly with the nanowire length, with a typical value of 1 nH/um for NbN and 44 pH/um for Nb at a temperature of 2.5 K. We measure the temperature and current dependence of the kinetic inductance and compare our results to theoretical predictions. We also simulate the self-resonant frequencies of these nanowires in a compact meander geometry. These nanowire inductive elements have applications in a variety of microwave frequency superconducting circuits.