Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France.
Pitaevskii BEC Center, CNR-INO and Dipartimento di Fisica, Università di Trento, I-38123 Trento, Italy and Trento Institute for Fundamental Physics and Applications, INFN, 38123 Trento, Italy.
Phys Rev Lett. 2023 Jun 2;130(22):226003. doi: 10.1103/PhysRevLett.130.226003.
At zero temperature, a Galilean-invariant Bose fluid is expected to be fully superfluid. Here we investigate theoretically and experimentally the quenching of the superfluid density of a dilute Bose-Einstein condensate due to the breaking of translational (and thus Galilean) invariance by an external 1D periodic potential. Both Leggett's bound fixed by the knowledge of the total density and the anisotropy of the sound velocity provide a consistent determination of the superfluid fraction. The use of a large-period lattice emphasizes the important role of two-body interactions on superfluidity.
在零温度下，伽利略不变的玻色流体预计将完全超流。在这里，我们通过外部一维周期性势来理论和实验研究由于平移（因此伽利略不变性）的破坏而导致的稀玻色-爱因斯坦凝聚体的超流密度的猝灭。Leggett 边界由总密度和声速各向异性的知识所固定，为超流分数提供了一致的确定。大周期格子的使用强调了两体相互作用对超流性的重要作用。
