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Pogosov, W V Okayama University
Machida, K Okayama University
We study the thermal fluctuations of vortex positions in small vortex clusters in a harmonically trapped rotating Bose-Einstein condensate. It is shown that the order-disorder transition of two-shell clusters occurs via the decoupling of shells with respect to each other. The corresponding "melting" temperature depends strongly on the commensurability between numbers of vortices in shells. We show that melting can be achieved at experimentally attainable parameters and very low temperatures. Also studied is the effect of thermal fluctuations on vortices in an anisotropic trap with small quadrupole deformation. We show that thermal fluctuations lead to the decoupling of a vortex cluster from the pinning potential produced by this deformation. The decoupling temperatures are estimated and strong commensurability effects are revealed.
Digital Object Identifer:10.1103/PhysRevA.74.023622
Published with permission from the copyright holder. This is the institute's copy, as published in Physical Review A, August 2006, Volume 74, Issue 2, Pages 8.
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Physical Review A
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