Abstract
The population transfer of stimulated Raman adiabatic passage (STIRAP) is investigated using a time-dependent quantum wave packet method. The population is transferred from an initial state to a target state through the interaction of the external laser field with the permanent dipole moment and the transition dipole moment. The laser field is composed of an infrared pulse and a near ultraviolet pulse. The two pulses with small detunings are more efficient to achieve the STIRAP transition. The process of STIRAP is sensitive to the detunings of the two pulses. When the two detunings are the same in a Λ transition or the positive detuning of the pump pulse is equal to the negative detuning of the Stokes pulse in a ladder transition, the final population in the intermediate state can be eliminated and the target population is increased.
Highlights
The initial and intermediate states are coupled through the interaction between the transition dipole moment and the pump pulse, and the Stokes pulse induces the population transfer from the intermediate state to the target state through the permanent dipole transition
Because there is a small amount of the population remained in the intermediate state at t > 30 ps, the pump pulse induces the population transfer between the states |νA = 2, jA = 1 and |νX = 0, jX = 0 and the population curves for P2A,1, P0X,0, PA and PX show weak oscillations
We have studied the population transfer of stimulated Raman adiabatic passage (STIRAP) through the interaction of external laser field with the permanent dipole moment and the transition dipole moment, with the LiH molecule as the example
Summary
The control of population transfer with properly designed laser fields allows one to manipulate the quantum states of atoms and molecules.[1,2,3,4,5] The stimulated Raman adiabatic passage (STIRAP) technique, which was introduced by Gaubatz et al.,[6,7] is an efficient way used for preparation of welldefined quantum states through population transfer.[8,9,10,11,12] In this technique, a complete population transfer from an initial state to a target state is achieved via an intermediate state which is coupled with the initial and target states by the pump and Stokes pulses, respectively. Shu et al have investigated the rovibrational dynamics of STIRAP in two electronic states.[18] Their results show that some rovibrational levels affect the dynamics of STIRAP, especially while the frequencies of two pulses do not satisfy the condition of the two-photon resonance. Because two near ultraviolet pulses are employed in their research, the permanent dipole moments have no effect on the processes of STIRAP. The interaction of the infrared pulses with the permanent dipole moment can drive population transfer in a single electronic state,[19,20] bus affect the processes of STIRAP in some conditions. The permanent dipole moments can affect phase-sensitive target populations in extended Λ systems.[22]
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