Hannover 2013 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 40: Quantum gases: Optical lattices II
Q 40.7: Vortrag
Mittwoch, 20. März 2013, 15:30–15:45, A 310
Emergence of coherence in optical lattices — •Simon Braun1,2, Sean Hodgman1,2, Michael Schreiber1,2, Philipp Ronzheimer1,2, Daniel Garbe1,2, Immanuel Bloch1,2, and Ulrich Schneider1,2 — 1Ludwig-Maximilians-Universität München — 2Max-Planck-Institut für Quantenoptik, Garching
Superfluidity in bosonic systems is fundamentally connected with the existence of long-range phase coherence. While this relationship is a well-established concept for equilibrium states also in optical lattices, much less is known about the dynamical emergence of coherence when the superfluid regime is entered. We present a detailed experimental study on how coherence of ultracold bosonic atoms in an optical lattice emerges when crossing the transition from the Mott insulating into the superfluid regime. We analyze the coherence length established in the system in dependence of the transition rate over the phase transition. We find a distinct symmetry between positive and negative temperature states at minimum and maximum kinetic energy, respectively, proving that the dynamics is independent of any residual non-local correlations in the initial Mott insulator. We investigate the behavior in different dimensions and also in an alternative scheme where coherence emerges in a static system after an initial quench.