INFLUENCE OF TYPICAL ENVIRONMENTS ON QUANTUM PROCESSES

We present the results of studying the influence of different environm ental states on the coherence of quantum processes. We choose to discu ss a simple model that describes two electronic reservoirs connected t hrough tunneling via a resonant state. The model could, e.g., serve as an idealization of inelastic resonant tunneling through a double-barr ier structure. We develop Schwinger's closed time path formulation of nonequilibrium quantum statistical mechanics, and show that the influe nce of the environment on a coherent quantum process can be described by the value of a generating functional at a specific force value, the reby allowing for a unified discussion of destruction of phase coheren ce by various environmental states: thermal state, classical noise, ti me-dependent classical field, and a coherent state. The model allows a n extensive discussion of the influence of dissipation on the coherent quantum process, and expressions for the transmission coefficient are obtained in the possible limits.