Volume 82, Number 3, May 2008
Article Number 30001
Number of page(s) 5
Section General
Published online 16 April 2008
EPL, 82 (2008) 30001
DOI: 10.1209/0295-5075/82/30001

Semiclassical theory of the quasi$\hbox{--}$two-dimensional trapped Bose gas

Markus Holzmann1, 2, Maguelonne Chevallier3 and Werner Krauth3

1  LPTMC, Université Pierre et Marie Curie - 4 Place Jussieu, 75005 Paris, France, EU
2  LPMMC, CNRS-UJF - BP 166, 38042 Grenoble, France, EU
3  CNRS-Laboratoire de Physique Statistique, Ecole Normale Supérieure - 24 rue Lhomond, 75231 Paris Cedex 05, France, EU

received 18 January 2008; accepted in final form 9 March 2008; published May 2008
published online 16 April 2008

We discuss the quasi$\hbox{--}$two-dimensional trapped Bose gas where the thermal occupation of excited states in the tightly confined direction is small but remains finite in the thermodynamic limit. We show that the semiclassical theory describes very accurately the density profile obtained by quantum Monte Carlo calculations in the normal phase above the Kosterlitz-Thouless temperature T$_{\rm KT}$, but differs strongly from the predictions of strictly two-dimensional mean-field theory, even at relatively high temperature. We discuss the relevance of our findings for analyzing ultra-cold$\hbox{--}$atom experiments in quasi$\hbox{--}$two-dimensional traps.

03.75.Hh - Static properties of condensates; thermodynamical, statistical, and structural properties.
05.30.Jp - Boson systems.

© EPLA 2008