Revealing the Superfluid Lambda Transition in the Universal Thermodynamics of a Unitary Fermi Gas
Revealing the Superfluid Lambda Transition in the Universal Thermodynamics of a Unitary Fermi Gas
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DOI：
10.1126/science.1214987
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发表时间：
2012-02-03
期刊：
影响因子：
56.9
通讯作者：
Zwierlein, Martin W.
中科院分区：
文献类型：
--
作者：
Ku, Mark J. H.;Sommer, Ariel T.;Zwierlein, Martin W.
费米气体，费米子的集合，如中子和电子，在自然界中发现，从固体到中子星。相互作用的费米气体可以形成超流体，或者对于带电的费米子，形成超导体。通过对费米气体局部压缩系数、密度和压强的高精度测量，我们观测到了强相互作用费米气体中的超流相变。我们的数据完全确定了这些气体的普遍热力学，没有任何合适的或外部的温度计。在可压缩性、化学势、熵和热容中观察到超流性的开始，其在临界温度T-c/T-F = 0.167（13）处显示出特征性的类牛顿特征。基态能量为3/5 xi N E-F，xi = 0.376（4）。我们的测量为强相互作用费米子的多体理论提供了一个基准。
Fermi gases, collections of fermions such as neutrons and electrons, are found throughout nature, from solids to neutron stars. Interacting Fermi gases can form a superfluid or, for charged fermions, a superconductor. We have observed the superfluid phase transition in a strongly interacting Fermi gas by high-precision measurements of the local compressibility, density, and pressure. Our data completely determine the universal thermodynamics of these gases without any fit or external thermometer. The onset of superfluidity is observed in the compressibility, the chemical potential, the entropy, and the heat capacity, which displays a characteristic lambda-like feature at the critical temperature T-c/T-F = 0.167(13). The ground-state energy is 3/5 xi N E-F with xi = 0.376(4). Our measurements provide a benchmark for many-body theories of strongly interacting fermions.