Random Lasing in an Inhomogeneous and Disordered System of Cold Atoms

We consider light trapping in an amplifying medium consisting of cold alkali-metal atoms; the atomic gas plays a dual role as a scattering and as a gain medium. We perform Monte-Carlo simulations for the combined processes. In some configurations of the inhomogeneous distribution this leads to a point of instability behavior and a signature of random lasing in a cold atomic gas.Comment: 10 pages, 5 figure

Coherent backscattering under conditions of electromagnetically induced transparency

We consider the influence of a resonant control field on weak localization of light in ultracold atomic ensembles. Both steady-state and pulsed light excitation are considered. We show that the presence of a control field essentially changes the type of interference effects which occur under conditions of multiple scattering. For example, for some scattering polarization channels the presence of a control field can cause destructive interference through which the enhancement factor, normally considered to be greater than one, becomes less than one.Comment: Submitted to Journal of Modern Optics, Special Issue: Proceedings of PQE 201

Imaging-based Parametric Resonance in an Optical Dipole Atom Trap

We report sensitive detection of parametric resonances in a high-density sample of ultracold $^{87}Rb$ atoms confined to a far-off-resonance optical dipole trap. Fluorescence imaging of the expanded ultracold atom cloud after a period of parametric excitation shows significant modification of the atomic spatial distribution and has high sensitivity compared with traditional measurements of parametrically-driven trap loss. Using this approach, a significant shift of the parametric resonance frequency is observed, and attributed to the anharmonic shape of the dipole trap potential

A scaling law for light scattering from dense and cold atomic ensembles

We calculate the differential cross section of polarized light scattering from a cold and dense atomic ensemble. The regularities in the transformation of the cross section when increasing the size of the atomic ensemble are analyzed numerically. We show that for typical experimental conditions, an approximate scaling law can be obtained. Very good agreement is found in a comparison with experimental data on the size dependence of a dense and cold cloud of 87$Rb atoms.Comment: Submitted to Journal of Modern Optics, Special issue on the Proceedings of the Colloquium on the Physics of Quantum Electronic

Light trapping in high-density ultracold atomic gases for quantum memory applications

High-density and ultracold atomic gases have emerged as promising media for storage of individual photons for quantum memory applications. In this paper we provide an overview of our theoretical and experimental efforts in this direction, with particular attention paid to manipulation of light storage (a) through complex recurrent optical scattering processes in very high density gases (b) by an external control field in a characteristic electromagnetically induced transparency configuration.Comment: Submitted to Journal of Modern Optics, Special 2010 PQE Issu