Stability, Adiabaticity and Transfer efficiency in a nonlinear \Lambda-system

TL;DR

This paper explores how the timing and stability of laser pulses affect the efficiency of transferring atoms to molecules in a nonlinear b1-system, highlighting the importance of laser overlap and chirping for optimal results.

Contribution

It demonstrates that proper laser overlap and pulse chirping can maintain adiabaticity and improve transfer efficiency in a nonlinear b1-system, even under instability conditions.

Findings

Laser overlap causes CPT state instability.

Short laser overlap preserves adiabaticity.

Chirped pulses compensate frequency shifts.

Abstract

We investigate the relationship between stability, adiabaticity and transfer efficiency in a \Lambda-type atom-molecule coupling system via a nonlinear stimulated Raman adiabatic passage. We find that only when the pump and control lasers overlap in time domain, the coherent population trapping (CPT) state could become unstable. If the overlapping time of the two lasers is short so that unstable growth of the deviation from the CPT state is negligible, then good adiabaticity of the CPT state could be maintained even in the unstable region. In this case, a high atom-molecule transfer efficiency could be obtained by chirping applied laser pulses to elegantly compensate the frequency shift induced by intra-atomic collision. Our results could be useful for efficiently photoassociating ground-state molecules from a cold atomic gas with strong atom-atom collisional interaction.