DYNAMICS OF THE MICROMASER FIELD

The field of the one-atom maser or micromaser shows abrupt variations of its strength in certain parameter regions. In this paper the time b ehavior of the field in the vicinity of those regions is investigated. The transition rate between the metastable states depends on the expe rimental parameters. Hysteresis behavior also occurs. The experimental results are compared to a quantum Monte Carlo simulation of the maser field as well as to the result of a Fokker-Planck treatment used earl ier in connection with micromaser theory. In the case of high pump rat es, Ramsey-type interference structures in the micromaser resonance li nes are observed. The resonance lines are obtained by recording the at omic inversion while scanning the cavity frequency across the atomic r esonance. The interferences occur owing to the mixing of the coupled s tates of the atom-held system at the entrance and exit holes of the ca vity, this leading to a Ramsey-type atom-field interaction scheme. The interference patterns observed in the experiment are approximately pe riodic. Individual interference fringes are triangular-shaped, whereby the steep high-frequency edges are related to metastability and hyste resis phenomena of the maser held. The observations are explained on t he basis of a modified micromaser theory.