Photoassociation dynamics driven by a modulated two-color laser field

Photoassociation (PA) dynamics of ultracold cesium atoms steered by a modulated two-color laser field E(t)=E0f(t)cos((2π/Tp)-φ)cos(ωLt) is investigated theoretically by numerically solving the time-dependent Schroedinger equation. The PA dynamics is sensitive to the phase of envelope (POE) φ and the period of the envelope Tp, which indicates that it can be controlled by varying POE φ and period Tp. Moreover, we introduce the time- and frequency-resolved spectrum to illustrate how the POE φ and the period Tp influence the intensity distribution of the modulated laser pulse and hence change the time-dependent population distribution of photoassociated molecules. When the Gaussian envelope contains a few oscillations, the PA efficiency is also dependent on POE φ. The modulated two-color laser field is available in the current experiment based on laser mode-lock technology.