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

• Contributions to the current noise induced by superconducting fluctuations are calculated.
• Nonequilibrium physics is studied.
• Nonlinear dependence of the noise on temperatures and chemical potentials of the reservoirs is found.

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.