Optical Guiding of Trapped Atoms by a Blue-Detuned Hollow Laser Beam in the Horizontal Direction

Optical guiding of ⁸⁵Rb atoms in a magneto-optical trap (MOT) by a blue-detuned horizontal hollow laser beam is demonstrated experimentally. The guiding efficiency and the velocity distribution of the guided atoms are found to have strong dependence on the detuning of the guiding laser. In particular, the optimum guiding occurs when the blue detuning of the hollow laser beam is approximately equal to the hyperfine structure splitting of the ⁸⁵Rb ground states, in good agreement with the theoretical analysis based on a three-level model.