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Real-time dynamics of lattice bosons from nonequilibrium dynamical mean-field theory

Hugo Strand, University of Fribourg, Switzerland

17.10.2014 at 09:00 

We extend the bosonic dynamical mean-field formalism to nonequilibrium situations and test it in combination with a Nambu real-time strong coupling perturbative impurity solver [1]. The formalism correctly describes the Mott insulating, superfluid and normal phases, and captures damping and thermalization at finite temperatures, in contrast to other real-time approaches.

As a first application we study bosonic cold-atoms in an optical lattice using the Bose-Hubbard model. We drive the system out of equilibrium by quenching the interaction, mimicking the seminal cold-atom experiment of Greiner et al. [2]. Starting from both the normal and superfluid phase, we map out non-equilibrium phase diagrams which identify the different dynamical regimes. A multitude of behaviors are observed, including rapid thermalization and trapping in meta-stable normal and superfluid states. Depending on parameters, the condensate displays long lived or strongly damped amplitude oscillations.

Nonequilibrium bosonic dynamical mean-field theory can be straightforwardly extended to enable the study of the nonequilibrium properties of bosonic multi-component systems [3] and Bose-Fermi mixtures [4].

1. H. U. R. Strand, M. Eckstein, P. Werner, arXiv:1405.6941 (2014)
2. M. Greiner, O. Mandel, T. W. Hansch, I. Bloch, Nature 419, 51 (2002)
3. A. Hubener, M. Snoek, W. Hofstetter, PRB 80, 245109 (2009)
4. P. Anders, P. Werner, M. Troyer, M. Sigrist, L. Pollet, PRL 109, 206401 (2012)

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