Twisted optical molasses for all-optical atomic cooling and trapping

We explain how a proper specification of the spatial field distribution and angular momentum content of a twisted light beam propagating in an arbitrary direction can be made using appropriate transformations. Such transformations are needed whenever a light beam is to be combined with other similar beams propagating in specified directions. The transformation procedure greatly facilitates the evaluations of the radiation forces acting on atoms subject to an arbitrary set of twisted light beams. It allows atomic trajectories in one-, two-, and three-dimensional optical molasses configurations to be correctly evaluated. We find that multiple twisted beams offer a flexible means of controlling the motion of atoms, but there are notable features attributable only to the orbital optical angular momentum property of the twisted light. Under suitable conditions, atoms can be decelerated and ultimately made to congregate in specific regions of space. The implications of this for all-optical atomic cooling and trapping using twisted light are pointed out and discussed.