Suppression of ac Stark shift scattering rate due to non-Markovian behavior

Abstract

The ac Stark shift in the presence of spontaneous decay is typically considered to induce an effective dephasing with a scattering rate equal to $\hat{I}{“}_s|\hat{I}\text{c◯}{|}^2/\hat{I}{”}^2$, where $\hat{I}{“}_s$ is the spontaneous decay rate, $\hat{I}\text{c◯}$ is the laser transition coupling, and $\hat{I}”$ is the detuning. We show that under realistic circumstances this dephasing rate may be strongly modifed due to non-Markovian behavior. The non-Markovian behavior arises due to an effective modification of the light-atom coupling in the presence of the ac Stark shift laser. An analytical formula for the non-Markovian ac Stark shift induced dephasing is derived. We obtain that for narrow laser linewidths the effective dephasing rate is suppressed by a factor of $Q^2$, where $Q$ is the quality factor of the laser.

Accepted in PRA Rapid Communications