Vortices are fundamental excitations of gases and liquids.
Well-known examples include tornados, whirlpools, and smoke rings. The main characteristic of vortices is that nearby matter tends to flow in circles around the core. Quantum mechanics says that all the atoms in these quantum fluids can be described by the same single wavefunction. Since the motion of atoms in one location is linked with the motion of atoms everywhere else, atoms can flow in circles only in very special ways. There are many ways of creating vortices in fluids.