title: Anomalous Broadening in Driven Dissipative Rydberg Systems.
abstract: We observe interaction-induced broadening of the two-photon 5s-18s transition in ^{87}Rb atoms trapped in a 3D optical lattice. The measured linewidth increases by nearly 2 orders of magnitude with increasing atomic density and excitation strength, with corresponding suppression of resonant scattering and enhancement of off-resonant scattering. We attribute the increased linewidth to resonant dipole-dipole interactions of 18s atoms with blackbody induced population in nearby np states. Over a range of initial atomic densities and excitation strengths, the transition width is described by a single function of the steady-state density of Rydberg atoms, and the observed resonant excitation rate corresponds to that of a two-level system with the measured, rather than natural, linewidth. The broadening mechanism observed here is likely to have negative implications for many proposals with coherently interacting Rydberg atoms.
authors.affiliation: United States Army Research Laboratory, Adelphi, Maryland 20783, USA.
authors.forename: E A
authors.initials: EA
authors.lastname: Goldschmidt
authors.affiliation: Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899, USA.
authors.forename: T
authors.initials: T
authors.lastname: Boulier
authors.affiliation: Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Brown
authors.affiliation: Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899, USA.
authors.forename: S B
authors.initials: SB
authors.lastname: Koller
authors.affiliation: Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Young
authors.affiliation: Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899, USA.|Joint Center for Quantum Information and Computer Science, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742, USA.
authors.forename: A V
authors.initials: AV
authors.lastname: Gorshkov
authors.affiliation: Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899, USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Rolston
authors.affiliation: Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899, USA.
authors.forename: J V
authors.initials: JV
authors.lastname: Porto