Berlin 2014 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 32: Poster: Quantum gases, ultracold atoms and molecules

Q 32.16: Poster

Mittwoch, 19. März 2014, 16:30–18:30, Spree-Palais

Study of doublon dynamics in the Bose-Hubbard model using low-energy theories — •Holger Niehus and Daniela Pfannkuche — I. Institut für Theoretische Physik, Universität Hamburg, 20355 Hamburg, Deutschland

Identifying the relevant processes for the dynamics of excitations far from equilibrium is one of the most challenging tasks in many particle physics. We approach this problem for a special class of excited states in the Bose-Hubbard model, so-called doublons, by means of effective low-energy models in conjunction with exact diagonalization. For large on-site interaction U, doublons can not decay directly. The existence of a finite bandwidth and energy conservation prohibits the conversion of the interaction-energy of the two constituent particles to kinetic energy.

We study the interaction of few doublons by creating two doubly occupied sites in an otherwise empty lattice. The low-energy theory of third order in the hopping is recast to a doublon-doublon Hamiltonian capturing the essential dynamics. We further investigate the applicability of this model for many doublons and show in which cases the model may break down.

Complementary we study the influence of neighboring bosons on the dynamics of a single doublon. We show that the dynamics of such systems may be described by a doublon-holon model.