Ac-induced thermal vortex escape in magnetic-field-embedded long annular Josephson junctions

TL;DR

This paper models the thermal escape of magnetic fluxons in long annular Josephson junctions under ac perturbation, explaining experimentally observed multi-peaked escape distributions through classical dynamical resonances.

Contribution

It demonstrates that multi-peaked escape distributions can be explained by classical thermal models, linking experimental data to dynamical resonances in the sine-Gordon framework.

Findings

Multi-peaked escape distributions are reproduced by the classical model.

Resonances between ac perturbation and fluxon oscillations explain the peaks.

The model aligns with experimental observations at low temperatures.

Abstract

We investigate theoretically the thermal escape behavior of trapped magnetic fluxons in long annular Josephson junctions in dc magnetic fields, and perturbed by a probing ac current. The study is motivated by recently published experimental data that show multi-peaked escape distributions for increasing bias current in the extreme low temperature regime when the system is perturbed by an ac current. We demonstrate that the observed behavior of multi-peaked escape distributions can be reproduced and predicted in the entirely classical, thermally driven sine-Gordon model, which is widely accepted as accurately describing the experimental system. We interpret the observed multi-peaked distributions as being directly induced by dynamical resonances between the applied ac perturbation and the natural oscillation frequency of a trapped fluxon.