Observation of vortices and vortex stripes in a dipolar Bose-Einstein condensate

TL;DR

This paper reports the first observation of vortices and vortex stripes in a dipolar Bose-Einstein condensate, demonstrating anisotropic vortex arrangements induced by dipole interactions and rotation.

Contribution

It provides experimental evidence of vortices in dipolar quantum gases and confirms theoretical predictions of vortex stripe formations.

Findings

Vortices form in dipolar BECs under rotation.

Vortex stripes align along the magnetic field.

Experimental results agree with simulations.

Abstract

Quantized vortices are the prototypical feature of superfluidity. Pervasive in all natural systems, vortices are yet to be observed in dipolar quantum gases. 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 through magnetostriction, 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 corroboration with simulations--realizing a long sought-after prediction for dipolar vortices.