MICROMASER WITHOUT THE ROTATING-WAVE APPROXIMATION - THE BLOCH-SIEGERT SHIFT AND RELATED EFFECTS

The micromaser dynamics is studied without assuming the validity of th e rotating-wave approximation (RWA). Through numerically evaluating mi cromaser spectra for first and second order correlations we compare ou r results with those based on the RWA for both the resonant and the no nresonant case. We find that in the resonant case values of g/omega(0) -where g is the atom-field coupling constant and omega(0) the transiti on frequency - of the order of 10(-3) to 10(-4) would be necessary to achieve shifts of the spectra that would be larger than their correspo nding linewidths. These: shifts arise from typically quantum-mechanica l self-energy effects. In the nonresonant case, for detunings of the o rder of 1 MHz and within a parameter range of current experimental int erest (g/omega(0) = 10(-6)) we predict a relative shift. stemming from the Bloch-Siegert effect, for the case of spectra corresponding to tw o-photon correlations. Furthermore, we find that the RWA and non-RWA c ases are clearly resolved from each other when we plot the time evolut ion of second-order field correlations, These ran be put in correspond ence with atomic correlations that are measurable through selective fi eld ionization. (C) 1997 Elsevier Science B.V.