ONE-ATOM MASER WITH A PERIODIC AND NOISY PUMP - AN APPLICATION OF DAMPING BASES

We study the one-atom maser with a periodic-pump scheme for the inject ed atoms. The dynamics of the system is solved also in a regime where the losses of the field cannot be neglected while the atom is inside t he cavity, as is the situation in an optical maser. The time developme nt of the maser field is described by a general evolution operator, wh ose matrix representation in the damping basis is known analytically f or zero temperature. The numerical evaluation of this matrix yields th e stationary as well as the transient properties of the maser. Noise-p roducing mechanisms of the pump are included explicitly in the evoluti on operator for the field. These are a finite efficiency of the pump l aser, a velocity spread in the atomic beam, and spontaneous transition s between the atomic levels and to the ground state. We find that feat ures such as trapped states and sub-Poissonian photon statistics also occur in the high-loss regime like in an optical resonator. The observ ation of such effects will, as in the ordinary micromaser experiments, depend very sensitively on the reduction of the pump noise. For highl y regular excitation, we find a pronounced oscillation of the field-co rrelation function for a wide range of the transit time, which leads t o a distinct line splitting in the spectrum of the field. The amount o f the splitting is determined by the periodicity of the pump. For less regular excitation, and in particular in the Poissonian limit, these oscillations disappear.