Low-Loss Superconducting Nanowire Circuits Using a Neon Focused Ion Beam

TL;DR

This paper demonstrates low-loss superconducting nanowire resonators with high quality factors at millikelvin temperatures, highlighting their potential for quantum circuits and addressing photon sensitivity issues.

Contribution

It introduces superconducting nanowire-embedded resonators with ultra-narrow wires and achieves quality factors comparable to traditional Josephson devices, advancing quantum circuit technology.

Findings

Internal quality factor up to 3.9x10^5 at 300mK

Nanowire sensitivity to stray infrared photons

Potential for superconducting nanowire quantum circuits

Abstract

We present low-temperature measurements of low-loss superconducting nanowire-embedded resonators in the low-power limit relevant for quantum circuits. The superconducting resonators are embedded with superconducting nanowires with widths down to 20nm using a neon focused ion beam. In the low-power limit, we demonstrate an internal quality factor up to 3.9x10^5 at 300mK [implying a two-level-system-limited quality factor up to 2x10^5 at 10 mK], not only significantly higher than in similar devices but also matching the state of the art of conventional Josephson-junction-embedded resonators. We also show a high sensitivity of the nanowire to stray infrared photons, which is controllable by suitable precautions to minimize stray photons in the sample environment. Our results suggest that there are excellent prospects for superconducting-nanowire-based quantum circuits.