Theory of two-dimensional macroscopic quantum tunneling in a Josephson junction coupled with an LC circuit

TL;DR

This paper provides a theoretical analysis of how coupling a Josephson junction with an LC circuit affects thermal activation and quantum tunneling escape rates, revealing suppression of quantum tunneling and slight reduction of thermal activation.

Contribution

It introduces a two-dimensional model for classical and quantum phase dynamics in Josephson junctions coupled with LC circuits, providing analytical escape rate calculations.

Findings

MQT escape rate is significantly suppressed by LC coupling

TA escape rate experiences slight reduction due to coupling

Results help interpret recent experiments on YBCO Josephson junctions

Abstract

We investigate classical thermal activation (TA) and macroscopic quantum tunneling (MQT) for a Josephson junction coupled with an LC circuit theoretically. The TA and MQT escape rate are calculated analytically by taking into account the two-dimensional nature of the classical and quantum phase dynamics. We find that the MQT escape rate is largely suppressed by the coupling to the LC circuit. On the other hand, this coupling gives rise to slight reduction of the TA escape rate. These results are relevant for the interpretation of a recent experiment on the MQT and TA phenomena in grain boundary YBCO Josephson junctions.