Transient velocity-selective coherent population trapping in one dimension

We show theoretically that velocity-selective coherent population trapping in one dimension may be realized in atomic transitions other than Jg = 1 ↔ Je = 1. The atomic momentum distribution resulting from irradiation by counterpropagating σ+–σ− waves on the Jg = 3/2 ↔ Je = 1/2 and the Jg = 2 ↔ Je = 1 atomic transitions is investigated through solution of the optical Bloch equations and determination of the effective loss rates for atomic eigenstates. An inverted-W atomic level configuration is also used to investigate the features of velocity-selective coherent population trapping. The momentum distribution exhibits peaks at the ±ħk or the ±ħ2k and the 0 momenta, depending on the atomic transitions and the laser intensity. These structures, generated by atomic states that do not interact with the laser radiation, are stable when associated with eigenstates of the kinetic energy, or metastables; i.e., the structures last several hundred spontaneous lifetimes when generated by nonexact kinetic-energy eigenstates.