Crossover from Kramers to phase-diffusion switching in hysteretic DC-SQUIDs

TL;DR

This paper investigates the transition in switching behavior of hysteretic DC-SQUIDs from Kramers' regime to phase diffusion, highlighting the impact of environmental impedance and retrapping on switching rates.

Contribution

It introduces a model for switching rates in the phase diffusion regime, accounting for retrapping effects influenced by environmental impedance.

Findings

Switching rates are reduced due to retrapping effects.

A peaked second moment of switching distribution occurs as a function of temperature.

Peak temperatures scale with the critical current of the DC-SQUID.

Abstract

We have measured and propose a model for switching rates in hysteretic DC-SQUID in the regime where phase diffusion processes start to occur. We show that the switching rates in this regime are smaller than the rates given by Kramers' formula due to retrapping of Josephson phase. The retrapping process, which is affected by the frequency dependent impedance of the environment of the DC-SQUID, leads to a peaked second moment of the switching distribution as a function of temperature. The temperature where the peaks occur are proportional to the critical current of the DC- SQUID.