Berlin 2012 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 1: Correlated Electrons: Low-dimensional Systems - Models 1
TT 1.3: Vortrag
Montag, 26. März 2012, 10:00–10:15, H 0104
Ballistic expansion of interacting fermions in one-dimensional optical lattices — •Stephan Langer1, Martin Schuetz3, Ian McCulloch2, Ulrich Schollwöck1, and Fabian Heidrich-Meisner1 — 1LMU München — 2University of Queensland, Brisbane, Australia — 3MPQ Garching and LMU München
In most quantum quenches, no net
particle currents arise. Access to studying transport properties can be gained
by letting a two-component Fermi gas that is originally confined by the
presence of a trapping potential expand into an empty optical lattice. In
recent experiments, this situation was addressed in 2D and 3D optical lattices
[1]. We focus on the 1D case in which an exact numerical simulation of the
time-evolution is possible by means of the DMRG method. Concretely, we study
the expansion in the 1D Hubbard model with repulsive interactions, driven by
quenching the trapping potential to zero, and we concentrate on the most direct
experimental observable, namely density profiles [2]. In the strict 1D case, we
identify conditions for which the expansion is ballistic, characterized by an
increase of the cloud’s radius that is linear in time. This behavior is
found whenever initial densities are smaller or equal to one, both for the
expansion from box and harmonic traps. We make quantitative predictions for the
expansion velocity as a function of on-site repulsion and initial density that
can be probed in experiments.
Schneider et al., arXiv:1005.3545
Langer et al., arXiv:1109.4364