Dresden 2011 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 19: Quantum Gases: Miscellaneous
Q 19.7: Vortrag
Dienstag, 15. März 2011, 12:15–12:30, HÜL 386
Comparison of stochastic techniques for finite temperature Bose gases — Stuart Cockburn1, •Antonio Negretti2, Nikolaos Proukakis1, and Carsten Henkel3 — 1School of Mathematics and Statistics, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, United Kingdom — 2Institut für Quanteninformationsverarbeitung, Universität Ulm, Albert- Einstein-Allee 11, 89069 Ulm, Germany — 3Institut für Physik und Astronomie, Universität Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany
In this talk we analyze two stochastic approaches for describing weakly interacting, trapped quasi-one-dimensional Bose gases at finite temperatures: a number-conserving Bogoliubov (ncB) approach and a stochastic Gross-Pitaevskii equation (sGPe). Density profiles, correlation functions, and the condensate statistics are compared to predictions based upon alternative theories. Although the two stochastic methods are built on different thermodynamic ensembles (ncB: canonical, sGPe:grand-canonical), they yield the correct condensate statistics in a large BEC (strong enough particle interactions). For smaller systems, the sGPe results are prone to anomalously large number fluctuations, well-known for the grand-canonical, ideal Bose gas, whereas the ncB approach, due to thermal phase fluctuations, loses its validity at relatively low temperatures.