Environmental effects on Coulomb blockade in a small tunnel junction: A nonperturbative calculation

A nonperturbative theory of environmental effects on the Coulomb blockade of single-electron tunneling, using the nonequilibrium Green's-function technique and the path-integral method, is presented. A set of self-consistent equations for the current-voltage (I-V) characteristics and the related correlation functions is derived. It is demonstrated that the two existing theories, viz., the microscopic phase correlation theory and the phenomenological quantum Langevin equation approach, are just two special cases of the present self-consistent theory under some particular approximations.