Macroscopic quantum tunneling in "small" Josephson junctions in magnetic field

TL;DR

This paper investigates macroscopic quantum tunneling in small Josephson junctions under magnetic fields, analyzing how the magnetic field influences tunneling behavior and calculating key parameters like crossover temperature and escape time.

Contribution

It introduces a model for MQT in finite-size Josephson junctions with magnetic fields, extending previous point-like analyses to spatially dependent potentials.

Findings

Derived the general expression for the crossover temperature T_0.

Calculated the escape time tau_esc for the junctions.

Analyzed the effect of magnetic field-induced Fraunhofer modulation on MQT.

Abstract

We study the phenomenon of macroscopic quantum tunneling (MQT) in small Josephson junctions (JJ) with an externally applied magnetic field. The latter results in the appearance of the Fraunhofer type modulation of the current density along the barrier. The problem of MQT for a point-like JJ is reduced to the motion of the quantum particle in the washboard potential. In the case of a finite size JJ under consideration, this problem corresponds to a MQT in potential which itself, besides the phase, depends on space variables. Finally, the general expression for the crossover temperature T_0 between thermally activated and macroscopic quantum tunneling regimes and the escaping time tau_esc have been calculated.