Examples of superfluidity can be found in superconductors, Helium, and more recently in BEC gas. Quantized vortices are the signature of superfluidity.

When a bucket of water is placed on a rotating turn-table, gradually the water starts to rotate uniformly with the glass. Yet, the rotation of superfluid is inhomogeneous: it circulates around quantized vortex lines where the vorticity concentrate, and there is little vorticity outside of the lines.

Models to study the quantized vortices in BEC are often taken to be the Gross-Pitaevskii equations, which we have extensively studied and simulated.

There is a story of quantized vortices beyond rotation, as told in our PRL paper.