Stuttgart 2012 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 63: Ultra-cold atoms, ions and BEC IV

Q 63.6: Vortrag

Freitag, 16. März 2012, 12:00–12:15, V57.03

Dynamical arrest of ultracold lattice fermions. — •Bernd Schmidt1, M. Reza Bakhtiari1, Irakli Titvinidze1,2, Ulrich Schneider3, Michiel Snoek4, and Walter Hofstetter11Institut für Theoretische Physik, Goethe-Universität Frankfurt, Frankfurt/Main, Germany — 2Institut für Theoretische Physik, Universität Hamburg, Hamburg, Germany — 3Ludwig-Maximilians-Universität, München, Germany — 4Institute for Theoretical Physics, Universiteit van Amsterdam, Amsterdam, The Netherlands

When a parameter of a system is changed non-adiabatically, it might happen that under certain conditions the system freezes in a meta-stable state and will not be able to reach equilibrium again. This kind of phenomenon is often called dynamical arrest and is a well known effect in other fields of physics, for example, the gelation of colloidal systems in soft-matter physics. We investigate a very similar effect in a cloud of fermionic atoms during the ramp-up of an optical lattice. We use Dynamical Mean Field Theory to calculate the equilibrium radius of the cloud and compare it to experimental results. This comparison reveals that the system gets indeed trapped into a meta-stable state. Although the theoretical equilibrium behaviour of the system shows an anomalous expansion of the cloud as in the experiment, the experimental size of the cloud is significantly affected by dynamical arrest. Using a combination of numerical simulations and experimental data we are able to determine the critical lattice depth of dynamical arrest. Our results are of major relevance for the interpretation of past and future experiments with attractive fermions in optical lattices.

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