Quantum analysis of optical bistability and spectrum of fluctuations

Abstract

We discuss the approach to equilibrium and the fluctuations of a bistable system under dynamical conditions such that the field variables can be eliminated adiabatically. The atomic system evolves under the action of the coherent pumping of an external field and of collective and incoherent relaxation processes. The competition between pumping and relaxation effects causes the atomic steady-state configurations to depend discontinuously on the strength of the driving field. We derive an explicit expression for the spectrum of the forward-scattered light, which exhibits hysteresis and a discontinuous dependence on the driving-field amplitude.