Instanton Glass Generated by Noise in a Josephson-Junction Array

TL;DR

This paper analyzes how weak Gaussian noise affects the superconducting correlations in a 2D Josephson-junction array, revealing a state akin to a collective Cooper-pair insulator with exponential decay of correlations at low temperatures.

Contribution

It provides a theoretical computation of correlation functions in noisy Josephson arrays, linking noise effects to insulating behavior similar to disordered superconductors.

Findings

Correlations decay exponentially at low temperatures with large Josephson coupling.

The noisy array exhibits properties similar to a collective Cooper-pair insulator.

The state persists regardless of noise strength when coupling dominates.

Abstract

We compute correlation function of a superconducting order parameter in a continuous model of a two-dimensional Josephson-junction array in the presence of a weak Gaussian noise. When the Josephson coupling is large compared to the charging energy the correlations in the Euclidian space decay exponentially at low temperatures regardless of the strength of the noise. We interpret such a state as a collective Cooper-pair insulator and argue that it resembles properties of disordered superconducting films.