Frankfurt 2006 – wissenschaftliches Programm

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Q: Quantenoptik und Photonik

Q 34: Poster Quantengase

Q 34.8: Poster

Dienstag, 14. März 2006, 16:30–18:30, Labsaal

Excitations and correlations in the dynamics of Bose-Einstein condensates — •Thomas Ernst, Michael Hartung, Tobias Paul, Klaus Richter, and Peter Schlagheck — Institut für Theoretische Physik, Regensburg

We study the coherent flow of a Bose-Einstein condensate through a quantum point contact in a magnetic waveguide beyond the quasi one-dimensional adiabatic mean-field regime [1]. The population of transverse excitations in the waveguide is accounted for by a Bogoliubov-like linearization procedure. We show, that the contribution of such transverse excitations may cause significant modifications of the transmission through the point contact. In order to go beyond the mean-field approximation, we use a refined version of a microscopic quantum dynamics approach [2] which is based on the method of noncommutative cumulants. Instead of using normal-ordered correlation functions and their system of equations, we calculate the dynamics of their appropriate cumulants according to Wick’s theorem. This method is number-conserving, contains for situations close to equilibrium the Bogoliubov approach, but accounts also for highly non-equilibrium situations and allows to compute excitations of the condensate as well as its depletion rate. We apply this approach to elementary transport processes in one dimension.

[1] P. Leboeuf and N. Pavloff, Phys. Rev. A 64, 033602 (2001)

[2] T. Köhler and K. Burnett, Phys. Rev. A 65, 033601 (2002)