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A: Fachverband Atomphysik

A 14: Poster I - Ultra-cold atoms, ions and BEC

A 14.5: Poster

Dienstag, 20. März 2007, 16:30–18:30, Poster B

Thermal dephasing of a Bose- Einstein Condensate in a double well potential — Walter Strunz and •Sigmund Heller — Physikalisches Institut, Universität Freiburg, Hermann- Herder- Straße 3 79104 Freiburg i. Br.

Our primary goal is a thorough understanding of the phase of a Bose- Einstein- condensate in a double well potential. Within a two mode model [1,2] we calculate the phase classically and quantum mechanically and compare it with experimental results of the Oberthaler group (Heidelberg University)[3]. The ground state and first excited state are obtained by a 3D imaginary time propagation.

In order to consider the influence of additional states we introduce a new stochastic Gross- Pitaevskii equation for finite temperature that provides the canonical ensemble on average. We discuss properties of this Langevin equation.

[1] L. Pitaevskii and S. Stringari. Phys. Rev. Lett. 87.180402 (2001).

[2] D. Ananikan and T. Bergemann. Phys. Rev. A 73.013604 (2006).

[3] R. Gati, B. Hemmerling, J. Foelling, M. Albiez and M. K. Oberthaler. Phys. Rev. Lett. 96.130404 (2006).