Broadening in many-body multi-level Rydberg systems
Rydberg atoms exhibit strong, controllable, long-range interactions that are of great interest for quantum information applications and studies of many-body physics. However, most theoretical treatments of Rydberg systems ignore their multi-level nature and its role in spontaneous decay and light scattering. We study Rydberg excitation of atoms in dense cloud of 87Rb atoms trapped in a 3D optical lattice and observe dramatic broadening of the two-photon 5s-18s Rydberg transition. We attribute the broadening to dipole-dipole interactions of 18s atoms with atoms in nearby Rydberg states populated by spontaneous decay from the 18s. The presence of these spontaneously created atoms dramatically affects the ability to coherently address the transition of interest either resonantly or with detuned light intended to mix the ground and Rydberg state, a popular idea known as Rydberg dressing. I will present experimental data showing nearly two orders of magnitude of broadening, and correspondingly altered scattering rates, and discuss the various effects of this phenomenon on many-body Rydberg physics.