Superfluidity of Bose—Einstein condensates in ultracold atomic gases*
Zhu Qi-Zhonga), Wu Biaoa),b),c)†
       
(a) A superfluid with SOC moves while the tube is at rest. (b) The superfluid is dragged by a tube moving at the speed of v . (c) An impurity moves at v in the SOC superfluid. The reference frame is the lab. The two-way arrow indicates the equivalence between different scenarios and the arrow with a bar indicates the non-equivalence.