Superconducting granular aluminum resonators resilient to magnetic fields up to 1 Tesla

TL;DR

This study demonstrates that superconducting granular aluminum resonators maintain high quality factors up to 1 Tesla magnetic fields, making them suitable for quantum circuits requiring magnetic field resilience.

Contribution

The paper shows that granular aluminum microwave resonators retain high internal quality factors in magnetic fields up to 1 Tesla, a significant advancement for quantum device applications.

Findings

$Q_{i}$ exceeds $10^5$ up to 1T magnetic field

Small perpendicular fields (~0.5mT) enhance $Q_{i}$ by ~15%

Higher perpendicular fields degrade the resonators' quality factor

Abstract

High kinetic inductance materials constitute a valuable resource for superconducting quantum circuits and hybrid architectures. Superconducting granular aluminum (grAl) reaches kinetic sheet inductances in the nH/$\square$ range, with proven applicability in superconducting quantum bits and microwave detectors. Here we show that the single photon internal quality factor $Q_{\mathrm{i}}$ of grAl microwave resonators exceeds $10^5$ in magnetic fields up to 1T, aligned in-plane to the grAl films. Small perpendicular magnetic fields, in the range of 0.5mT, enhance $Q_{\mathrm{i}}$ by approximately 15%, possibly due to the introduction of quasiparticle traps in the form of fluxons. Further increasing the perpendicular field deteriorates the resonators' quality factor. These results open the door for the use of high kinetic inductance grAl structures in circuit quantum electrodynamics and hybrid architectures with magnetic field requirements.