We present a semiclassical theory of the micromaser by using a consistent multiple-time-scale expansion of its dynamics. The time scale over which the semiclassical approximation is valid is established, and the effects of quantum and thermal fluctuations in the long-time limit are investigated. A thermodynamical analogy is introduced to interpret the steady-state properties of the micromaser, and we show that a simple model allowing for two-phase coexistence provides the best agreement between the semiclassical and quantum theories.

• Received 4 May 1989

DOI:https://doi.org/10.1103/PhysRevA.40.2471