High Kinetic Inductance Superconducting Nanowire Resonators for Circuit QED in a Magnetic Field

TL;DR

This paper introduces superconducting nanowire resonators with high quality factors in strong magnetic fields, enabling advanced circuit QED experiments involving quantum dots and magnetic environments.

Contribution

The development of NbTiN nanowire resonators with high magnetic field resilience and enhanced zero-point voltage fluctuations for circuit QED applications.

Findings

Intrinsic quality factors exceed 2×10^5 at 6 T magnetic field.

Resonators maintain quality factors above 3×10^4 at 350 mT perpendicular field.

High characteristic impedance enhances zero-point voltage fluctuations.

Abstract

We present superconducting microwave-frequency resonators based on NbTiN nanowires. The small cross section of the nanowires minimizes vortex generation, making the resonators resilient to magnetic fields. Measured intrinsic quality factors exceed $2\times 10^5$ in a $6$ T in-plane magnetic field, and $3\times 10^4$ in a $350$ mT perpendicular magnetic field. Due to their high characteristic impedance, these resonators are expected to develop zero-point voltage fluctuations one order of magnitude larger than in standard coplanar waveguide resonators. These properties make the nanowire resonators well suited for circuit QED experiments needing strong coupling to quantum systems with small electric dipole moments and requiring a magnetic field, such as electrons in single and double quantum dots.