Density correlations in ultracold atomic Fermi gases

被引:20
作者
Belzig, W. [1 ]
Schroll, C.
Bruder, C.
机构
[1] Univ Konstanz, Dept Phys, D-78457 Constance, Germany
[2] Univ Basel, Dept Phys & Astron, CH-4056 Basel, Switzerland
来源
PHYSICAL REVIEW A | 2007年 / 75卷 / 06期
关键词
D O I
10.1103/PhysRevA.75.063611
中图分类号
O43 [光学];
学科分类号
070207 ; 0803 ;
摘要
We investigate density fluctuations in a coherent ensemble of interacting fermionic atoms. Adapting the concept of full counting statistics, well known from quantum optics and mesoscopic electron transport, we study second-order as well as higher-order correlators of density fluctuations. Using the mean-field BCS state to describe the whole interval between the BCS limit and the Bose-Einstein condensate (BEC) limit, we obtain an exact expression for the cumulant-generating function of the density fluctuations of an atomic cloud. In the two-dimensional case, we obtain a closed analytical expression. Poissonian fluctuations of a molecular condensate on the BEC side are strongly suppressed on the BCS side. The size of the fluctuations in the BCS limit is a direct measure of the pairing potential. We also discuss the BEC-BCS crossover of the third cumulant and the temperature dependence of the second cumulant.
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页数:5
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