Thermodynamic Limit in Quantum Stochastic Process

Abstract

Asymptotic evaluation of quantum mechanical master equation of specific form is presented. It is shown in the thermodynamic limit that time evolution of intensive observables and that of fluctuation observables are given by a set of ordinary differential equations and a master equation of the type of damped harmonic oscillators, respectively. This can be regarded as a quantum mechanical extension of van Kampen's system size expansion method. Two applications are shown: 1) super-radiance from two level atoms and from Josephson oscillators, and 2) laser oscillation caused by two-photon process.