Vortices are ubiquitous in nature and they appear in all kinds of fluids.
Ordinary vortices in fluids
A vortex is typically created due to disturbances of the flow in the fluid.
https://images.app.goo.gl/C79XAvnrtCPuRsfz7
A series of vortices in a fluid. The fluid may rotate clockwise or anticlockwise around the vortex center. The vortices may be large or small.
If fluid flows forward, typically, two counter-rotating vortices will be created.
If fluid flows forward, typically, two counter-rotating vortices will be created.
Quantized vortices in superfluids
Gases from vapours of alkali metals can be cooled down to a few nK and they form a state of matter called a Bose-Einstein condensate (BEC). This is a quantum fluid and discrete quantum states are anticipated.
A BEC of cold atoms (Dalibard group, ENS Paris). The atoms are trapped in a harmonic (confining) potential.
Flow of the superfluid around the center of the condensate can be sustained if a vortex if formed.
These vortices are quantised, because there are only a discrete number of ways that they may form. The flow velocity around the center of the vortex is quantised.
There is full depletion of fluid at the vortex center.
A superfluid vortex.
A number of quantised vortices are produced if the superfluid is forced to rotate faster.
https://images.app.goo.gl/xSGhiGA8TGbb4DZk7
Other examples include vortices in superconductors, optics, etc.
Breaking news (16/4/2023)