Regensburg 2013 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 25: Correlated Electrons: Low-Dimensional Systems - Models 3
TT 25.9: Talk
Tuesday, March 12, 2013, 12:00–12:15, H9
Expansion dynamics of interacting bosons in homogeneous lattices — •Jens Philipp Ronzheimer1,2, Michael Schreiber1,2, Simon Braun1,2, Sean S. Hodgman1,2, Stephan Langer2,3, Ian P. McCulloch4, Fabian Heidrich-Meisner5,2, Immanuel Bloch1,2, and Ulrich Schneider1,2 — 1LMU München — 2MPQ Garching — 3University of Pittsburgh, USA — 4University of Queensland, Brisbane, Australia — 5Universität Erlangen-Nürnberg, Erlangen
We study out-of-equilibrium dynamics and transport properties of interacting many-body systems using ultracold atoms in optical lattices. Specifically, we experimentally and numerically investigate the expansion dynamics of initially localized bosons in homogeneous 1D and 2D Hubbard systems. We find that the fastest, ballistic expansions occur in the integrable limits of the system. In 1D, these are both the non-interacting and the strongly-interacting limits where the system enters into the hard-core boson regime. Any deviation from these limits, either through finite interactions or the admixture of double occupancies in the initial state, significantly slows down the expansion. In 2D, the strongly interacting limit is fundamentally different. The system expands ballistically only in the non-interacting case, while all interactions lead to strongly diffusive behavior. This is in full analogy to previous experiments with interacting fermions. By controlling the tunneling along individual lattice axes, we can gradually change the dimensionality of the system from 1D to 2D. In the strongly interacting case, we observe how the initially ballistic dynamics in a 1D system turn diffusive when additional degrees of freedom become available.