Observation of a 2D Bose gas: from thermal to quasicondensate to superfluid.
Observation of a 2D Bose gas: from thermal to quasicondensate to superfluid.
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DOI：
10.1103/physrevlett.102.170401
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发表时间：
2008-05
影响因子：
8.6
通讯作者：
Anand Ramanthan;P. 'e;C. Ryu;K. Helmerson;W. Phillips
中科院分区：
文献类型：
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作者：
Anand Ramanthan;P. 'e;C. Ryu;K. Helmerson;W. Phillips
我们展示了准二维几何中玻色气体在 Berezinskii、Kosterlitz 和 Thouless (BKT) 转变温度附近的实验结果。通过测量飞行时间后的密度分布和相干长度，我们可以识别气体的不同状态。我们观察到气体形成双峰分布，没有长程有序。在这种情况下，气体呈现出比热云更长的相干长度；它是准凝聚态，但不是超流体。实验证据表明我们还观察到超流体转变（BKT 转变）。对于足够长的飞行时间，当气体形成超流体成分时，我们观察到三峰分布。
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 after time of flight and the coherence length, we identify different states of the gas. We observe that the gas develops a bimodal distribution without long range order. In this regime, the gas presents a longer coherence length than the thermal cloud; it is quasicondensed but is not superfluid. Experimental evidence indicates that we also observe the superfluid transition (BKT transition). For a sufficiently long time of flight, we observe a trimodal distribution when the gas has developed a superfluid component.