Optical dipole force on ladder-like three-level atomic systems driven by chirped few-cycle-pulse laser fields

摘要

We report a study on the optical dipole force in a ladder like three levelatomic systems in the context of coherent population transfer with the chirpedfew-cycle-pulse laser fields. The phenomenon of coherent population transfer isinvestigated by numerically solving the appropriate density matrix equationsbeyond the rotating wave approximation. On the other hand, optical dipole forceis calculated by numerically solving the force equation and density matrixequations self-consistently. By analysing the centre-of-mass motion, it isshown that the optical dipole force with chirped pulses may be used forfocusing and defocusing of atoms in an atomic beam similar to the near ornon-resonant optical dipole force. Moreover, the robustness of the populationtransfer against the variation of the pulse parameters and the effect of thevariation of the Rabi frequencies and the chirp rates on the optical dipoleforce are also investigated. The proposed scheme may open new perspectives inthe focusing and de-focusing of atoms and molecules in an atomic beam, sincethis scheme mitigates the demand for the generation of transform-limited pulselaser fields at arbitrary frequencies.