Menotti C, Pedri P, Stringari S
Dipartimento di Fisica, Università di Trento and BEC-INFM, I-38050 Povo, Italy.
Phys Rev Lett. 2002 Dec 16;89(25):250402. doi: 10.1103/PhysRevLett.89.250402. Epub 2002 Dec 2.
We study the expansion of a dilute ultracold sample of fermions initially trapped in an anisotropic harmonic trap. The expansion of the cloud provides valuable information about the state of the system and the role of interactions. In particular, the time evolution of the deformation of the expanding cloud behaves quite differently depending on whether the system is in the normal or in the superfluid phase. For the superfluid phase, we predict an inversion of the deformation of the sample, similar to what happens with Bose-Einstein condensates. Vice versa, in the normal phase, the inversion of the aspect ratio is never achieved, if the mean field interaction is attractive and collisions are negligible.
我们研究了最初被困在各向异性谐波势阱中的稀薄超冷费米子样本的膨胀。云团的膨胀提供了有关系统状态和相互作用作用的有价值信息。特别是，膨胀云团变形的时间演化行为根据系统处于正常相还是超流相而有很大不同。对于超流相，我们预测样本变形会发生反转，类似于玻色 - 爱因斯坦凝聚体的情况。反之，在正常相中，如果平均场相互作用是吸引性的且碰撞可忽略不计，则纵横比的反转永远不会实现。
