Decay and Fluctuation of a One-Dimensional Supercurrent from the Viewpoint of Nonlinear Nonequilibrium Statistical Physics

Abstract

Relaxation and fluctuation of a supercurrent in a thin superconducting wire are studied from the viewpoint of statistical physics of nonlinear non-equilibrium processes with the use of a stochastic model discussed previously by Langer and Ambegaokar. It is emphasized that the supercurrent is a typical physical example to which one can apply the system-size Ω-expansion method developed by van Kampen and Kubo. The nonlinear equations derived by van Kampen and Kubo for the deterministic path of an intensive macrovariable and the variance around it are extended so as to be used for the supercurrent. By solving the equations, nonlinear relaxation and fluctuations of the supercurrent are calculated explicitly for various initial conditions.