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arXiv · 0805.3519

Observation of a 2D Bose-gas: from thermal to quasi-condensate to superfluid

P. Cladé·C. Ryu·A. Ramanathan·K. Helmerson·W. D. Phillips
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Abstract

We present experimental results on a Bose gas in a quasi-2D geometry near the Berezinskii, Kosterlitz and Thouless (BKT) transition temperature. By measuring the density profile, \textit{in situ} and after time of flight, and the coherence length, we identify different states of the gas. In particular, we observe that the gas develops a bimodal distribution without long range order. In this state, the gas presents a longer coherence length than the thermal cloud; it is quasi-condensed but is not superfluid. Experimental evidence indicates that we observe the superfluid transition (BKT transition).

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P. Cladé, C. Ryu, A. Ramanathan, K. Helmerson, W. D. Phillips. 2008-05-22. Observation of a 2D Bose-gas: from thermal to quasi-condensate to superfluid. https://doi.org/10.1103/physrevlett.102.170401

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