Equilibrium resistance fluctuations

Abstract

This paper is addressed to a theoretical understanding of the relation proposed by Voss and Clarke between nonequilibrium steady-state voltage fluctuations and equilibrium fluctuations in the band-limited Johnson-noise power. A nonlinear Langevin model is presented which satisfies local charge conservation and the fluctuation-dissipation theorem, and exhibits Gaussian equaltime statistics. The mode couplings in this model yield, in the appropriate limit, a non-Gaussian component in the equilibrium four-time voltage correlation function. This component can be interpreted in terms of equilibrium resistance fluctuations. It is also shown that the same mode-coupling terms give a small fluctuation renormalization of the average resistance. Our model is related to recently proposed Fokker-Planck models, in which local transport coefficients are functions of the instantaneous values of the state variables.