Hannover 2020 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 10: Ultra-cold atoms, ions, and BEC II (joint session A/Q)

Q 10.5: Talk

Monday, March 9, 2020, 15:15–15:30, f303

Josephson effects in coupled anisotropic Bose-Einstein condensates — •Marc Momme, Yuriy Bidasyuk, and Michael Weyrauch — Physikalisch-Technische Bundesanstalt, Braunschweig, Germany

Josephson effects can manifest in a bose-condensed atomic gas with two components, if the phase of both components remains (mostly) coherent. That way, many experimental and theoretical studies of bosonic Josephson effects have been conducted to gain insight about the nature of macroscopic quantum coherence. The common theoretical description for such systems is the two-mode model, which relies on the assumption that the coupling between two components is much weaker then the energy required to create excitations inside each condensate. However if the Josephson oscillations couple with the longitudinal modes of the trap, the two-mode approximation is no longer valid.

The present study focuses on one system where such a coupling can occur: the bosonic equivalent of a long Josephson junction. Thereby a BEC is put in a cigar-shaped trap with the barrier parallel to the long axis of the trap. Effectively, two coupled quasi one-dimensional condensates are formed. We compare the results of mean-field numerical simulations with predictions of simplified effective models. We show how collective excitations influence the population dynamics of the condensates.