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

arXiv · 1702.08326

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

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Abstract

We study the expansion behaviours 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 $\bar{\gamma}$ of Equation-of-State of Fermionic superfluid is extracted. The $\bar{\gamma}$ 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.

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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. 2017-02-27. Oscillatory-like Expansion of a Fermionic Superfluid. https://doi.org/10.1016/j.scib.2019.10.022

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