All-optical manipulation of neutral atomic ensembles

The longitudinal and transverse evolution of thermal clouds have been studied experimentally and theoretically in blue-detuned hollow tunnels. Tunnels based on axicon generation and holographic phase-mask generation have been investigated. A simple model is presented that (1) accounts for longitudinal acceleration and (2) shows that a cloud confined in a tunnel with a potential having a Bessel mode distribution will absorb fewer photons than it would confined in a comparable tunnel with a Laguerre-Gaussian mode distribution. The longitudinal and transverse profiles are fit to analytical distributions functions from which we extract transverse and longitudinal temperatures of the cloud. We find the two temperatures to be very different, with the transverse temperature being as much as five times colder. Finally, we studied the energ level structure within a Bessel potential theoretically, and found that single-mode propagation is possible.