Effect of disorder on coherent quantum phase slips in Josephson junction chains

TL;DR

This paper investigates how different types of quenched disorder affect coherent quantum phase slips in Josephson junction chains, revealing that local junction parameters dominate fluctuations and that the total QPS amplitude can exhibit non-Gaussian statistics in shorter chains.

Contribution

It demonstrates that local junction parameters primarily influence phase-slip fluctuations, despite mode localization caused by disorder, and analyzes the statistical behavior of the total QPS amplitude.

Findings

Mode localization due to disorder has minimal impact on phase-slip fluctuations.

Fluctuations are mainly determined by local junction parameters.

Total QPS amplitude can be non-Gaussian in shorter chains.

Abstract

We study coherent quantum phase-slips in a Josephson junction chain, including two types of quenched disorder: random spatial modulation of the junction areas and random induced background charges. Usually, the quantum phase-slip amplitude is sensitive to the normal mode structure of superconducting phase oscillations in the ring (Mooij-Sch\"on modes, which are all localized by the area disorder). However, we show that the modes' contribution to the disorder-induced phase-slip action fluctuations is small, and the fluctuations of the action on different junctions are mainly determined by the local junction parameters. We study the statistics of the total QPS amplitude on the chain and show that it can be non-Gaussian for not sufficiently long chains.