Nonequilibrium stochastic transitions and quantum-mechanical tunnelling

Abstract

The classical problem of diffusion over a potential barrier and quantummechanical tunnelling through a barrier are shown not to be equivalent. In the classical case, the WKB approximation can only be applied when the thermodynamic potential has the Landau-Ginsberg form; the zeroth-order approximation coincides with Kramer’s approximation. For finite values of Boltzmann’s constant, for which random thermal fluctuations are taken into account, a nonequilibrium generalization of the Landau-Ginsberg theory is obtained.