Abstract

The one-atom maser or micromaser allows one to study the resonant interaction of a single atom with a single mode of a superconducting niobium cavity. In previous experiments values of the quality factor as high as 3·10¹⁰ have been achieved for the resonant mode, corresponding to an average lifetime of a photon in the cavity of 0.2 s. The photon lifetime is thus much longer than the interaction time of an atom with the maser field. The atoms used in the experiments are rubidium Rydberg atoms pumped by laser excitation into the upper level of the maser transition, which is usually induced between neighboring Rydberg states. In the experiments the atom-field interaction is probed by observing the population in the upper and lower maser levels after the atoms have left the cavity. The field in the cavity consists only of single or a few photons. Nevertheless, it is possible to study the interaction in considerable detail. Thus, the dynamics of the atom-field interaction treated with the Jaynes-Cummings model was investigated by selecting and varying the velocity of the pump atoms. The counting statistics of the pump atoms emerging from the cavity allowed to measure the non-classical character of the cavity field and recently, it was observed that under suitable experimental conditions the maser field exhibits bistability and hysteresis.

© 1996 IEEE