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Chin. Phys. B, 2022, Vol. 31(1): 016701    DOI: 10.1088/1674-1056/ac0dae

Observation of the BEC-BCS crossover in a degenerate Fermi gas of lithium atoms

Xiang-Chuan Yan(严祥传)1,3, Da-Li Sun(孙大立)1,†, Lu Wang(王璐)1,3, Jing Min(闵靖)1,3, Shi-Guo Peng(彭世国)1, and Kai-Jun Jiang(江开军)1,2,‡
1 State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China;
2 Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan 430071, China;
3 University of Chinese Academy of Sciences, Beijing 100049, China
Abstract  We observe characteristic atomic behaviors in the Bose-Einstein-condensation-Bardeen-Cooper-Schrieffer (BEC-BCS) crossover, by accurately tuning the magnetic field across the Feshbach resonance of lithium atoms. The magnetic field is calibrated by measuring the Zeeman shift of the optical transition. A non-monotonic anisotropic expansion is observed across the Feshbach resonance. The density distribution is explored in different interacting regimes, where a condensate of diatomic molecules forms in the BEC limit with the indication of a bimodal distribution. We also measure the three-body recombination atom loss in the BEC-BCS crossover, and find that the magnetic field of the maximum atom loss is in the BEC limit and gets closer to the Feshbach resonance when decreasing the atom temperature, which agrees with previous experiments and theoretical prediction. This work builds up a controllable platform for the study on the strongly interacting Fermi gas.
Keywords:  BEC-BCS crossover      three-body recombination      anisotropic expansion  
Received:  19 May 2021      Revised:  31 May 2021      Accepted manuscript online:  23 June 2021
PACS:  67.85.-d (Ultracold gases, trapped gases)  
  03.75.Ss (Degenerate Fermi gases)  
  67.10.Db (Fermion degeneracy)  
Fund: This work has been supported by the National Key Research and Development Program of China (Grant No. 2016YFA0301503), the National Natural Science Foundation of China (Grant Nos. 11674358, 11434015, and 11974384), Chinese Academy of Sciences (Grant No. YJKYYQ20170025), and K.C. Wong Education Foundation (Grant No. GJTD-2019-15)).
Corresponding Authors:  Da-Li Sun, Da-Li Sun     E-mail:;

Cite this article: 

Xiang-Chuan Yan(严祥传), Da-Li Sun(孙大立), Lu Wang(王璐), Jing Min(闵靖), Shi-Guo Peng(彭世国), and Kai-Jun Jiang(江开军) Observation of the BEC-BCS crossover in a degenerate Fermi gas of lithium atoms 2022 Chin. Phys. B 31 016701

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