Optical dipole force on ladderlike three-level atomic systems induced by few-cycle-pulse laser fields

We report on a study of the optical dipole force in a ladderlike three-level atomic system induced by the trains of few-cycle-pulse laser fields. In the present study, we consider the nonresonant as well as the chirped pulse excitation of three-level atoms. The so-called optical dipole force is calculated by numerically solving the force equation and the density matrix equations self-consistently beyond the rotating wave approximations. By analyzing the center-of-mass motion, it is shown that under nonresonant excitation, the optical dipole force induced by the trains of few-cycle pulses may be used for focusing and defocusing of atoms in an atomic beam. Moreover, we have demonstrated that the chirped nanosecond pulses may be used for both coherent population transfer and focusing or defocusing of atoms simultaneously.