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

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 نشر من قبل Kristian Helmerson
 تاريخ النشر 2008
  مجال البحث فيزياء
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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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