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Frontiers of Physics

ISSN 2095-0462

ISSN 2095-0470(Online)

CN 11-5994/O4

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Front. Phys.    2014, Vol. 9 Issue (5) : 539-570    https://doi.org/10.1007/s11467-014-0448-7
REVIEW ARTICLE
Pseudogap phenomena in ultracold atomic Fermi gases
Qijin Chen(), Jibiao Wang
Department of Physics and Zhejiang Institute of Modern Physics, Zhejiang University, Hangzhou 310027, China
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Abstract

The pairing and superfluid phenomena in a two-component ultracold atomic Fermi gas is an analogue of Cooper pairing and superconductivity in an electron system, in particular, the high Tcsuperconductors. Owing to the various tunable parameters that have been made accessible experimentally in recent years, atomic Fermi gases can be explored as a prototype or quantum simulator of superconductors. It is hoped that, utilizing such an analogy, the study of atomic Fermi gases may shed light to the mysteries of high Tcsuperconductivity. One obstacle to the ultimate understanding of high Tcsuperconductivity, from day one of its discovery, is the anomalous yet widespread pseudogap phenomena, for which a consensus is yet to be reached within the physics community, after over 27 years of intensive research efforts. In this article, we shall review the progress in the study of pseudogap phenomena in atomic Fermi gases in terms of both theoretical understanding and experimental observations. We show that there is strong, unambiguous evidence for the existence of a pseudogap in strongly interacting Fermi gases. In this context, we shall present a pairing fluctuation theory of the pseudogap physics and show that it is indeed a strong candidate theory for high Tcsuperconductivity.

Keywords pseudogap      pairing fluctuation theory      atomic Fermi gases      BCS–BEC crossover      high Tcsuperconductivity     
Corresponding Author(s): Qijin Chen   
Issue Date: 15 October 2014
 Cite this article:   
Qijin Chen,Jibiao Wang. Pseudogap phenomena in ultracold atomic Fermi gases[J]. Front. Phys. , 2014, 9(5): 539-570.
 URL:  
https://academic.hep.com.cn/fop/EN/10.1007/s11467-014-0448-7
https://academic.hep.com.cn/fop/EN/Y2014/V9/I5/539
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152 The curves in Fig. 19 were calculated using a two-channel model. Nevertheless, for wide Feshbach resonances such as in 6Li and 40K, the closed-channel fraction is very small [191, 192] so that the quantitative difference in the entropy s(r) between the two-channel and one-channel model is negligible.
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155 Note that the experimental data cannot be measuring Nc = N as shown in Fig. 18, since at 1/(kF a) = −1,Nc = N is far below the experimental threshold of detection.
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