ATOMIC-BEAM CORRELATIONS AND THE QUANTUM STATE OF THE MICROMASER

Correlation measurements on the states of two-level atoms having passe d through a micromaser at different times can be used to infer propert ies of the quantum stale of the radiation field in the cavity, Long(sh ort) correlation length in time is to som extent associated with super (sub)-Poissonian photon statistics. The correlation length is also an indicator of a phase structure much richer than what is revealed by th e usual single-time observables, like the atomic inversion or the Mand el quality factor. In realistic experimental situations the correlatio ns may extend over many times the decay time of the cavity, Our assert ions are verified by comparing theoretical calculations with a high-pr ecision Monte-Carlo simulation of the micromaser system.