Ultracold highly excited atoms in a magneto-optical trap (MOT) are strongly coupled by the dipole-dipole interaction. We have investigated the importance of many-body effects by controlling the dimensionality and density of the excited sample. We excited three different cylindrical volumes of atoms in the MOT to Rydberg states. At small radius, where the sample is nearly one-dimensional, many-body interactions are suppressed. At larger radii, the sample becomes three-dimensional and many-body effects are apparent.
Carroll, Thomas J.; Sunder, Shubha; and Noel, Michael W., "Many-body Interactions in a Sample of Ultracold Rydberg Atoms with Varying Dimensions and Densities" (2006). Physics and Astronomy Faculty Publications. Paper 2.