Rostock 2019 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 12: Ultra-cold atoms, ions and BEC

A 12.15: Poster

Dienstag, 12. März 2019, 16:30–18:30, S Fobau Physik

Coherent oscillations between anisotropic Bose-Einstein condensates — •Marc Ruben Momme, Yuriy Mikhailovich Bidasyuk, and Michael Weyrauch — Physikalisch-Technische Bundesanstalt, Bundesallee 100, D-38116 Braunschweig, Germany

Josephson effects in Bose-condensed atomic gases receive a considerable interest from experimental and theoretical studies as a prominent manifestation of quantum coherence on macroscopic scale.

The common theoretical description for such systems is the two-mode model. Its validity relies on the assumption that the coupling between two BECs is much weaker then the energy required to create excitations inside each condensate. However if such excitations are present in the same low-energy region, the two-mode model may no longer be valid.

Our results focus on one particular example of such a system: a BEC in a highly anisotropic, cigar-shaped harmonic trap with a barrier parallel to the long axis. The dynamics are modeled within a mean-field framework of the two-dimensional Gross-Pitaevskii equation. We compare the predictions of the two-mode model with the spectrum of the Bogoliubov-de Gennes equation and we show how the lowest Bogoliubov excitations contribute to the dynamics of the system.