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 our experiments we achieve values of the quality factor of up to 4×10¹⁰, corresponding to an average lifetime of a photon in the cavity of 0.3 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 maser level, 63 P_3/2, the lower maser level is either the 61 D_5/2 or the 61 D_3/2 depending on the cavity frequency. The atom field dynamics is observed by measuring the atoms in the upper or lower maser levels after the cavity. During the interaction the field in the cavity consists only of single or a few photons, nevertheless, it is possible to study the interaction in detail. Thus, the dynamics of the interaction described by the Jaynes-Cummings model can be controlled by changing the velocity i.e. the interaction time of the atoms. The atom rate is such that on average there is much less than a single atom in the cavity at one time. During the interaction with the cavity the atom and field become entangled, therefore the detection of the state of an outgoing atom gives information on the field states of the cavity.

© 2000 IEEE