Fluctuation-induced noise in out-of-equilibrium disordered superconducting films

TL;DR

This paper investigates fluctuation-induced noise in disordered superconducting films out of equilibrium, analyzing how different fluctuation processes affect transport properties near the superconducting transition.

Contribution

It provides a theoretical framework for calculating nonequilibrium current correlations considering multiple fluctuation contributions in disordered superconductors.

Findings

Derived the nonequilibrium current-current correlation function.

Quantified the impact of fluctuation processes on conductivity.

Connected out-of-equilibrium results to near-equilibrium fluctuation-dissipation relations.

Abstract

We study out-of-equilibrium transport in disordered superconductors close to the superconducting transition. We consider a thin film connected by resistive tunnel interfaces to thermal reservoirs having different chemical potentials and temperatures. The nonequilibrium longitudinal current-current correlation function is calculated within the nonlinear sigma model description and nonlinear dependence on temperatures and chemical potentials is obtained. Different contributions are calculated, originating from the fluctuation-induced suppression of the quasiparticle density of states, Maki- Thompson and Aslamazov-Larkin processes. As a special case of our results, close-to-equilibrium we obtain the longitudinal ac conductivity using the fluctuation-dissipation theorem.