title: Expansion dynamics of interacting bosons in homogeneous lattices in one and two dimensions.
abstract: We experimentally and numerically investigate the expansion of initially localized ultracold bosons in homogeneous one- and two-dimensional optical lattices. We find that both dimensionality and interaction strength crucially influence these nonequilibrium dynamics. While the atoms expand ballistically in all integrable limits, deviations from these limits dramatically suppress the expansion and lead to the appearance of almost bimodal cloud shapes, indicating diffusive dynamics in the center surrounded by ballistic wings. For strongly interacting bosons, we observe a dimensional crossover of the dynamics from ballistic in the one-dimensional hard-core case to diffusive in two dimensions, as well as a similar crossover when higher occupancies are introduced into the system.
authors.affiliation: Department of Physics, Ludwig-Maximilians-Universität München, 80799 München, Germany and Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany.
authors.forename: J P
authors.initials: JP
authors.lastname: Ronzheimer
authors.affiliation: Department of Physics, Ludwig-Maximilians-Universität München, 80799 München, Germany and Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schreiber
authors.affiliation: Department of Physics, Ludwig-Maximilians-Universität München, 80799 München, Germany and Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Braun
authors.affiliation: Department of Physics, Ludwig-Maximilians-Universität München, 80799 München, Germany and Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany.
authors.forename: S S
authors.initials: SS
authors.lastname: Hodgman
authors.affiliation: Department of Physics and Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, 80333 München, Germany and Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
authors.forename: S
authors.initials: S
authors.lastname: Langer
authors.affiliation: Centre for Engineered Quantum Systems, School of Mathematics and Physics, The University of Queensland, St. Lucia, QLD 4072, Australia.
authors.forename: I P
authors.initials: IP
authors.lastname: McCulloch
authors.affiliation: Department of Physics and Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, 80333 München, Germany and Friedrich-Alexander Universität Erlangen-Nürnberg, Institut für Theoretische Physik II, 91058 Erlangen, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Heidrich-Meisner
authors.affiliation: Department of Physics, Ludwig-Maximilians-Universität München, 80799 München, Germany and Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany.
authors.forename: I
authors.initials: I
authors.lastname: Bloch
authors.affiliation: Department of Physics, Ludwig-Maximilians-Universität München, 80799 München, Germany and Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Schneider