Vortex dynamics in two-dimensional Josephson junction arrays

TL;DR

This paper models vortex dynamics in 2D Josephson junction arrays near the Kosterlitz-Thouless transition, explaining experimental anomalies in dielectric response and flux noise spectra through vortex interactions and pair motions.

Contribution

It introduces a detailed theoretical framework for vortex dielectric function considering free vortices and pair motions, clarifying observed experimental anomalies.

Findings

Explanation of anomalous dielectric response features

Understanding flux noise spectra behavior

Differentiation of free vortex and pair contributions

Abstract

The dynamic response of unfrustrated two-dimensional Josephson junction arrays close to, but above the Kosterlitz-Thouless($KT$) transition temperature is described in terms of the vortex dielectric function $\epsilon(\omega)$. The latter is calculated by considering separately the contribution of $\ll$free$\gg$ vortices interacting by a screened Coulomb potential, and the $\ll$pair motion$\gg$ of vortices that are closer to each other than the $KT$ correlation length. This procedure allows to understand various anomalous features in $\epsilon(\omega)$ and in the flux noise spectra that have been observed experimentally and in dynamic simulations.