Atom motion in Laguerre-Gaussian doughnut beams

Summary form only given. Preparation of slow atomic beams has applications in experiments such as lithography, atom interferometry and in general for transporting atoms, for example from one vacuum chamber to another. Optical methods together with hollow fibers have been successfully employed to transport atoms, and all-optical methods using far off-resonant dipole forces have recently attracted much interest. Such all-optical methods have advantages in that far off-resonant dipole traps have potentially very low scattering rates, especially blue detuned hollow beam traps where atoms are restricted to low intensity regions where perturbations due to the light field are minimum. Optical atom guides also have practical advantages in that they can be switched, and can be easily introduced into high vacuum apparatus. Blue detuned hollow laser beams generated from a hollow optical fiber have been used to guide atoms (Xu et al, 1999; Babiker et al, 1994), and holographically generated doughnut beams have been used to guide and focus a cold beam of metastable neon atoms. In our experiments, we investigate the motion of cold rubidium atoms in far-detuned and near-resonant doughnut beams.