Oscillatory-like expansion of a Fermionic superfluid

Xiao-Qiong Wang; Yu-Ping Wu; Xiang-Pei Liu; Yu-Xuan Wang; Hao-Ze Chen; Mudassar Maraj; Youjin Deng; Xing-Can Yao; Yu-Ao Chen; Jian-Wei Pan

doi:10.1016/j.scib.2019.10.022

Oscillatory-like expansion of a Fermionic superfluid

Sci Bull (Beijing). 2020 Jan 15;65(1):7-11. doi: 10.1016/j.scib.2019.10.022. Epub 2019 Oct 25.

Authors

Affiliations

¹ Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China; CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China.
² Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China; CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China. Electronic address: yaoxing@ustc.edu.cn.
³ Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China; CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China. Electronic address: yuaochen@ustc.edu.cn.
⁴ Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Shanghai 201315, China; CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China. Electronic address: pan@ustc.edu.cn.

PMID: 36659071
DOI: 10.1016/j.scib.2019.10.022

Abstract

We study the expansion behaviors of a Fermionic superfluid in a cigar-shaped optical dipole trap for the whole BEC-BCS crossover and various temperatures. At low temperature (0.06(1)T_F), the atom cloud undergoes an anisotropic hydrodynamic expansion over 30 ms, which behaves like oscillation in the horizontal plane. By analyzing the expansion dynamics according to the superfluid hydrodynamic equation, the effective polytropic index γ¯ of Equation-of-State (EoS) of Fermionic superfluid is extracted. The γ¯ values show a non-monotonic behavior over the BEC-BCS crossover, and have a good agreement with the theoretical results in the unitarity and BEC side. The normalized quasi-frequencies of the oscillatory expansion are measured, which drop significantly from the BEC side to the BCS side and reach a minimum value of 1.73 around 1/k_Fa=-0.25. Our work improves the understanding of the dynamic properties of strongly interacting Fermi gas.

Keywords: BEC-BCS crossover; Equation-of-State; Fermionic superfluid; Oscillatory-like expansion.