Klaus Lauritz, Bland Thomas, Poli Elena, Politi Claudia, Lamporesi Giacomo, Casotti Eva, Bisset Russell N, Mark Manfred J, Ferlaino Francesca
Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria.
Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria.
Nat Phys. 2022;18(12):1453-1458. doi: 10.1038/s41567-022-01793-8. Epub 2022 Oct 31.
Quantized vortices are a prototypical feature of superfluidity that have been observed in multiple quantum gas experiments. But the occurrence of vortices in dipolar quantum gases-a class of ultracold gases characterized by long-range anisotropic interactions-has not been reported yet. Here we exploit the anisotropic nature of the dipole-dipole interaction of a dysprosium Bose-Einstein condensate to induce angular symmetry breaking in an otherwise cylindrically symmetric pancake-shaped trap. Tilting the magnetic field towards the radial plane deforms the cloud into an ellipsoid, which is then set into rotation. At stirring frequencies approaching the radial trap frequency, we observe the generation of dynamically unstable surface excitations, which cause angular momentum to be pumped into the system through vortices. Under continuous rotation, the vortices arrange into a stripe configuration along the field, in close agreement with numerical simulations.
量子化涡旋是超流性的一个典型特征，已在多个量子气体实验中被观测到。但是，偶极量子气体（一类以长程各向异性相互作用为特征的超冷气体）中涡旋的出现尚未见报道。在此，我们利用镝玻色-爱因斯坦凝聚体的偶极-偶极相互作用的各向异性本质，在原本呈圆柱对称的薄饼状阱中诱导角对称性破缺。将磁场朝径向平面倾斜会使云团变形为椭球体，然后使其旋转。在接近径向阱频率的搅拌频率下，我们观测到动态不稳定表面激发的产生，这会导致角动量通过涡旋被泵入系统。在持续旋转下，涡旋沿磁场排列成条纹构型，与数值模拟结果高度吻合。
