Hannover 2016 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 12: Ultra-cold atoms, ions and BEC (with A)

Q 12.24: Poster

Montag, 29. Februar 2016, 16:30–19:00, Empore Lichthof

Nonequilibrium Green functions approach to expansion dynamics in strongly correlated fermionic lattice systems — •Jan-Philip Joost, Niclas Schlünzen, Sebastian Hermanns, and Michael Bonitz — CAU Kiel, Germany

Experiments with ultracold atoms in optical lattices gained in importance over the last years and are of high current interest, since they allow to directly measure quantum behaviour and serve as a model for solid state systems [1]. The proper description of transport processes in quantum lattices in the regime of strong coupling is a challenging task, which has been limited, so far, to one-dimensional systems. The nonequilibrium Green functions [2] (NEGF) technique, however, is not restricted with respect to dimension or particle number. Combined with the T-matrix approximation [3], in particular, the NEGF method is well-suited to fill the gap for higher dimensions [4]. Here, we show results for strongly interacting fermions in 2D and 3D. The approach gives access to the short-time dynamics, as well as the long-time limit of the expansion. Beside the density and energy evolution, also the momentum distribution, dispersion relation and the site-resolved build-up of correlations are obtained, the latter of which can be verified experimentally using the recently developed fermionic atom microscopes.
  [1] U. Schneider et al., Nat. Phys. 8, 213 (2012)
  [2] K. Balzer and M. Bonitz, NEGF Approach to Inhomogeneous Systems, Lecture Notes in Physics (Springer, 2013)
  [3] M. P. von Friesen et al., Phys. Rev. B 82, 155108 (2010)
  [4] ngermanN. Schlünzen et al., arXiv:1508.02947 (2015)