Light pulse in Λ-type cold atomic gases

Date: 2010-04-12
Authors R. Wei, B. Zhao, Y. Deng, S. Chen, Z. -B. Chen, and J. -W. Pan
Journal No. Phys. Rev. A 81, 043403 (2010)
Abstract We investigate the behavior of the light pulse in Λ-type cold-atom gases with two counter-propagating control lights with equal strength by directly simulating the dynamic equations and exploring the dispersion relation. Our analysis shows that, depending on the length L0 of the stored wave packet and the decay rate γ of ground-spin coherence, the recreated light can behave differently. For long L0 and/or large γ, a stationary light pulse is produced, while two propagating light pulses appear for short L0 and/or small γ. In the γ→0 limit, the light always splits into two propagating pulses for a sufficiently long time. This scenario agrees with a recent experiment [ Y.-W. Lin et al. Phys. Rev. Lett. 102 213601 (2009)] where two propagating light pulses are generated in laser-cooled cold-atom ensembles.