arXiv 1408.58522014-08-25cond-mat.quant-gas

用全局变量测量玻色-爱因斯坦凝聚中的Heat Capacity

Measuring The Heat Capacity in a Bose-Einstein Condensation using Global Variables

R. F. Shiozaki, G. D. Telles, P. Castilho, F. J. Poveda-Cuevas, S. R. Muniz, G. Roati, V. Romero-Rochin, V. S. Bagnato

备注：: 9 pages, 4 figures
发表信息：: Physical Review A 90, 043640 (2014)
DOI：: 10.1103/PhysRevA.90.043640

摘要：

相变是很好理解的，通常伴随着相关热力学量的行为，例如在液氦的$λ$点超流转变的情况下，这是在其热容中观察到的。在被捕获的玻色-爱因斯坦凝聚体（BEC）的情况下，热容不能直接测量。在这项工作中，我们提出了一种技术，能够确定全球的热容量从密度分布的弱相互作用气体被困在一个非均匀的潜力。这种方法是一种替代模型的基础上局部密度近似。通过定义一对整体共轭变量，我们确定了总内能及其温度导数，热容。然后，我们将该技术应用于捕获的$^{87}$ Rb BEC，观察到取决于原子数的$λ$型跃迁，并讨论了与非相互作用、理想气体情况的偏差。最后讨论了用这种方法研究$T \rightarrow 0$热容的可能性。

英文摘要：

Phase transitions are well understood and generally followed by the behavior of the associated thermodynamic quantities, such as in the case of the $λ$ point superfluid transition of liquid helium, which is observed in its heat capacity. In the case of a trapped Bose-Einstein condensate (BEC), the heat capacity cannot be directly measured. In this work, we present a technique able to determine the global heat capacity from the density distribution of a weakly interacting gas trapped in an inhomogeneous potential. This approach represents an alternative to models based on local density approximation. By defining a pair of global conjugate variables, we determine the total internal energy and its temperature derivative, the heat capacity. We then apply the technique to a trapped $^{87}$Rb BEC a $λ$-type transition dependent on the atom number is observed, and the deviations from the non-interacting, ideal gas case are discussed. Finally we discuss the chances of using this method to study the heat capacity at $T \rightarrow 0$.

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摘要：

英文摘要：

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