Metastability in a nano-bridge based hysteretic DC-SQUID embedded in superconducting microwave resonator

TL;DR

This paper investigates the metastable behavior of a hysteretic DC-SQUID with nano-bridges, revealing diamond-shaped stability zones through experimental, analytical, and numerical methods, and demonstrating their manifestation in microwave resonator reflection patterns.

Contribution

It provides a comprehensive analysis of the metastability in a nano-bridge DC-SQUID, combining experimental observations with analytical and numerical modeling, including temperature effects and non-sinusoidal current-phase relations.

Findings

Diamond-like stability zones observed experimentally and in simulations.

Good agreement between theoretical models and experimental data.

Manifestation of stability zones in microwave resonator reflection patterns.

Abstract

We study the metastable response of a highly hysteretic DC-SQUID made of a Niobium loop interrupted by two nano-bridges. We excite the SQUID with an alternating current and with direct magnetic flux, and find different stability zones forming diamond-like structures in the measured voltage across the SQUID. When such a SQUID is embedded in a transmission line resonator similar diamond structures are observed in the reflection pattern of the resonator. We have calculated the DC-SQUID stability diagram in the plane of the exciting control parameters, both analytically and numerically. In addition, we have obtained numerical simulations of the SQUID equations of motion, taking into account temperature variations and non-sinusoidal current-phase relation of the nano-bridges. Good agreement is found between experimental and theoretical results.