Quantum theory of dissipation of a harmonic oscillator coupled to a nonequilibrium bath; Wigner-Weisskopf decay and physical spectra

摘要

We extend the quantum theory of dissipation in the context ofsystem-reservoir model, where the reservoir in question is kept in anonequilibrium condition. Based on a systematic separation of time scalesinvolved in the dynamics, appropriate generalizations of thefluctuation-dissipation and Einstein's relations have been pointed out. We showthat the Wigner-Weisskopf decay of the system mode results in a rate constantwhich depending on the relaxation of nonequilibrium bath is dynamicallymodified. We also calculate the time-dependent spectra of a cavity mode with asuitable gain when the cavity is kept in contact with a nonequilibrium bath.