Effects of the Center-of-Mass Motion on the Population Trapping of Ultracold Atoms

We investigate the effects of the atomic center-of-mass motion on atomic population trapping in a two-mode micromaser injected with ultracold Λ-type three-level atoms. We find that in the mazer regime (the case in which the atomic kinetic energy is much smaller than the atom-field interaction energy), the interplay between reflection and transmission of the ultracold atom leads to the destruction of the atomic population trapping.