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Phys. Rev. A 72, 013607 (2005) [9 pages]

Phase fluctuations of a Bose-Einstein condensate in low-dimensional geometry

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Demascoth Kadio1, Mariusz Gajda2,3, and Kazimierz Rzążewski1,3
1Center for Theoretical Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warszawa, Poland
2Institute of Physics, Polish Academy of Sciences,Aleja Lotników 32/46, 02-668 Warszawa, Poland
3Faculty of Mathematics and Natural Sciences, Cardinal Stefan Wyszyński University, Aleja Lotników 32/46, 02-668 Warszawa, Poland

Received 29 July 2004; revised 7 February 2005; published 11 July 2005

We investigate the phase fluctuations of a Bose-Einstein condensate in one- (1D) and three-dimensional (3D) elongated harmonic traps with the help of the numerical simulation using classical field approximation. By calculating the eigenvalues of the one-dimensional single-particle density matrix we show that the phase fluctuations of a Bose-Einstein Condensate in a 1D system are due to the thermal low-energy excitations. We find that the phase fluctuations depend on the temperature as has been predicted [Phys. Rev. Lett. 85, 3745 (2000), Phys. Rev. Lett. 87, 050404 (2001)]. Finally we show that the phase coherence length of a condensate in a harmonic trap depends on the aspect ratio of anisotropy (geometry) of the trap. We determine the border between the 3D and quasi-one-dimensional systems by calculating the phase coherence length of the condensate.


©2005 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevA.72.013607
DOI: 10.1103/PhysRevA.72.013607
PACS: 03.75.Hh, 03.75.Kk, 03.75.Nt

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