Thermal hopping and retrapping of a Brownian particle in the tilted periodic potential of a NbN/MgO/NbN Josephson junction

TL;DR

This study investigates the complex escape dynamics of a Brownian particle in a tilted periodic potential within a Josephson junction, revealing multiple hopping and retrapping phenomena through experimental and simulation analyses.

Contribution

It introduces a detailed experimental and theoretical analysis of multiple hopping and retrapping in Josephson junctions, highlighting the role of temperature and damping effects.

Findings

Second moment of switching distribution increases at low T

Distribution shape changes and narrows above T*

Model based on multiple retrapping fits experimental data well

Abstract

We report on the occurrence of multiple hopping and retrapping of a Brownian particle in a tilted washboard potential. The escape dynamic has been studied experimentally by measuring the switching current distributions as a function of temperature in a moderately damped NbN/MgO/NbN Josephson junction. At low temperatures the second moment of the distribution increases in agreement with calculations based on Kramers thermal activation regime. After a turn-over temperature T*, the shape of the distributions starts changing and width decreases with temperature. We analyze the data through fit of the switching probability and Monte Carlo simulations and we find a good agreement with a model based on a multiple retrapping process.