We demonstrate electromagnetically induced transparency with the control laser in a Laguerre-Gaussian mode. The transmission spectrum is studied in an ultracold gas for the D2 line in both $^{85}$Rb and $^{87}$Rb, where the decoherence due to diffusi
on of the atomic medium is negligible. We compare these results to a similar configuration, but with the control laser in the fundamental laser mode. We model the transmission of a probe laser under both configurations, and we find good agreement with the experiment. We conclude that the use of Laguerre-Gaussian modes in electromagnetically induced transparency results in narrower resonance linewidths as compared to uniform control laser intensity. The narrowing of the linewidth is caused by the spatial distribution of the Laguerre-Gaussian intensity profile.
Multiply-connected traps for cold, neutral atoms fix vortex cores of quantum gases. Laguerre-Gaussian laser modes are ideal for such traps due to their phase stability. We report theoretical calculations of the Bose-Einstein condensation transition p
roperties and thermal characteristics of neutral atoms trapped in multiply connected geometries formed by Laguerre-Gaussian LG{p}{l} beams. Specifically, we consider atoms confined to the anti-node of a LG{0}{1} laser mode detuned to the red of an atomic resonance frequency, and those confined in the node of a blue-detuned LG{1}{1} beam. We compare the results of using the full potential to those approximating the potential minimum with a simple harmonic oscillator potential. We find that deviations between calculations of the full potential and the simple harmonic oscillator can be up to 3%-8% for trap parameters consistent with typical experiments.
