Observation of vortices and vortex stripes in a dipolar BEC of magnetic atoms

Quantized vortices are one of the hallmarks of superfluidity and have been observed in numerous systems from liquid helium to quantum fluids of light, from superconductors to contact-interacting Bose-Einstein condensates (BECs). Here, we report on the first experimental observation of vortices in a strongly magnetic BEC of Dysprosium atoms, characterized by anisotropic long-range interaction. Unlike alkali atoms, which require complex techniques to impart angular momentum to the atomic cloud, dipolar quantum gases offer a unique opportunity. Following a new concept proposed in 2019, we are able to rotate the gas by revolving the magnetic field axis. Due to the phenomenon of magnetostriction, tilting the magnetic field towards the radial plane breaks the cylindrical symmetry of the cloud, which can then be set into rotation. We show that when the critical velocity is reached the system starts to nucleate vortices. We also observe one of the first predictions for vortices in presence of dipolar interaction: their rearrangement into stripes along the magnetic field direction. This new technique can be generalized to any quantum phase of dipolar gases, including the paradoxical supersolid phase, which still awaits direct observation of the superfluid irrotational properties.