Thermodynamics as a nonequilibrium path integral

Abstract

Thermodynamics is a well-developed tool to study systems in equilibrium but no such general framework is available for nonequilibrium processes. The only hope for a quantitative description is to fall back upon the equilibrium language as often done in biology. This gap is bridged by the work theorem. By using this theorem, we show that the Barkhausen-type nonequilibrium noise in a process, repeated many times, can be combined to construct a special matrix S whose principal eigenvector provides the equilibrium distribution. For an interacting system, S, the equilibrium distribution can be obtained from the free case without any requirement of equilibrium.