Critical point of an interacting two-dimensional atomic Bose gas.
We have measured the critical atom number in an array of harmonically trapped two-dimensional (2D) Bose gases of rubidium atoms at different temperatures. We found this number to be about 5 times higher than predicted by the semiclassical theory of Bose-Einstein condensation (BEC) in the ideal gas. This demonstrates that the conventional BEC picture is inapplicable in an interacting 2D atomic gas, in sharp contrast to the three-dimensional case. A simple heuristic model based on the Berezinskii-Kosterlitz-Thouless theory of 2D superfluidity and the local density approximation accounts well for our experimental results.
Krüger
Peter
P
Laboratoire Kastler Brossel and CNRS, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France.
Hadzibabic
Zoran
Z
Dalibard
Jean
J