Effect of coupling strength on atomic-to-molecular condensate conversion in Raman photoassociation

Abstract

We study two-photon Raman photoassociation for creating a coherent molecular Bose-Einstein condensate (BEC) from an atomic BEC. By exploring the dynamics of the coupled system, we show that the atom-to-molecule conversion efficiency can be controlled by changing the atom-molecule coupling strength and the effective two-photon Raman detuning. Atom-molecule coupling strength and the effective two-photon Raman detuning can be controlled by changing the laser intensity. We analyze the dynamics of the coupled atom-molecular condensate system by changing the laser intensity over a broad range, keeping the effective two-photon Raman detuning fixed. The effective two-photon Raman detuning depends on the two-photon detuning, Rabi frequencies, and the light shifting (AC Stark shift) of the levels. To keep the effective two-photon Raman detuning fixed, the two-photon detuning is varied to compensate for the light shifting of levels with laser intensity. The corresponding changes in the effective decay rates and the scattering length due to the change in the Rabi frequencies have been taken into account. Dependence of the conversion efficiency on the effective two-photon Raman detuning has also been studied by varying the laser intensity over a narrow range, keeping the two-photon detuning unchanged. The dynamics of the coupled system has been studied in Gross-Pitaevskii and modified Gross-Pitaevskii approaches to demonstrate the effect of the higher order nonlinearity (Lee-Huang-Yang term) with the increase in the laser intensity.

Coupled atomic–molecular condensates: role of Raman detuning on the dynamics

“…Levels |a and |v are coupled by a laser field with frequency ω 1 , while |v and are coupled by a second laser with frequency ω 2 . The process of Raman coupling becomes resonant when the Raman detuning δ [25] including the higher-order Lee-Huang-Yang effect in interatomic interactions along with s-wave scattering processes and laser-induced atom-to-molecule interconversion, the set of MGP equations for atomic (ψ a ) and molecular (ψ m ) condensate wave functions are…”

“…Investigations on the effect of Raman detuning on the conversion efficiency (from atoms to molecules) were also made during the evolution of coupled systems considering both GP and MGP approaches. We have theoretically explored the strategy of converting the atomic condensate into the condensate of diatomic molecules via Raman photoassociation leading to high conversion efficiency by controlling the intensity and the frequencies of the two coupling lasers [25]. We have also studied the dependence of collective excitation frequencies of the hybrid atomic-molecular system on effective Raman detuning, atom-molecule coupling strength as well as the s-wave scattering length [26].…”

Ultrafast population transfer in a Λ-configuration level system driven by few-cycle laser pulses

“…[4][5][6][7][8][9][10] Meanwhile, STIRAP has found a huge number of applications in atomic and molecular physics, such as the laser-assisted isomerization process, [11] selective dissociative in molecular systems, [12,13] and Raman photoassociation for creating a coherent molecular Bose-Einstein condensate (BEC) from an atomic BEC. [14][15][16] In short, the related population manipulation has become a very popular technique for coherent population transfer in quantum systems.…”