Darmstadt 2008 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 47: Quantengase (Bosonen II / Fermionen)

Q 47.1: Vortrag

Donnerstag, 13. März 2008, 16:30–16:45, 1A

Mean-field description of a decaying BEC — •Astrid Niederle, Eva-Maria Greafe, Hans Jürgen Korsch, Friederike Trimborn, and Dirk Witthaut — TU Kaiserslautern, Germany

A quantum system with decay can be effectively described by a non-Hermitian Hamiltonian with complex energy eigenvalues, whose imaginary parts describe the decay rate. In this talk we focus on a non-Hermitian, two-mode Bose-Hubbard Hamiltonian, which serves as a model for a Bose-Einstein-condensate in a double-well potential with decay from one of the two wells. We discuss the dynamics of operators, which is governed by a generalized Heisenberg-equation. Taking expectation values of the operators, we obtain a mean-field approximation. The resulting dynamics described by a generalized nonlinear Bloch equation is mainly influenced by the (up to four) fixed points, which can be repulsive or attractive depending on the system parameters. The mean-field dynamics is compared with the full N-particle quantum evolution.