Exact Langevin equation for electrons in thermostat, Fokker-Planck kinetics and flicker noise

Abstract

Generalized Langevin equation for characteristic functional of many-electron system dynamically interacting with a thermostat and besides subjected to external perturbation and observation is derived and formulated in terms of one-particle but stochastic density matrix. The scheme naturally includes also direct electron-electron interactions. Corresponding approximate Fokker-Plank kinetic equation is discussed. We point out that it possesses continuous degeneracy of stationary solution and therefore can hide long-correlated fluctuations of electron transport even if thermostat noise is short-correlated.