quantized vortex
/ KWON-tyzed VOR-teks /
Pull the plug in a bathtub and watch the water spin into a little whirlpool. The faster the swirl, the steeper the dip in the middle. In ordinary water that swirl can be of any strength at all — gentle, fierce, anything in between. A superfluid is far stricter: when it swirls, it is only allowed to do so in fixed, identical units.
A quantized vortex is one of these allowed whirlpools in a superfluid. Because the whole liquid shares one quantum wave, the amount of circulation around any whirlpool cannot take just any value; it can only be one fixed quantum's worth, or exactly two, or three, and nothing in between. Each vortex is a thin line, a tiny hole where the superfluid itself thins to nothing, with the liquid racing around it at a precisely set rate. Spin the container faster and the superfluid does not speed up smoothly; instead it sprouts more vortices, each carrying the same standard amount of swirl.
Quantized vortices matter because they are direct, countable proof of the quantum wave underlying the liquid, and they organize themselves into neat lattices that researchers photograph. A common misconception is that a vortex is just a dent in the surface like a bathtub drain; here the quantization — the fact that swirl comes only in whole steps — is the real point, and it is a strict rule, not an approximation.
Spin a small dish of Bose-condensed atoms and a tidy triangular array of vortices appears, each a tiny tornado carrying exactly the same quantum of swirl — add more rotation and you get more dots, never bigger ones.
A rotating condensate fills with identical quantized vortices arranged in a lattice.
The same quantization shows up in superconductors as flux vortices, where it is magnetic flux rather than fluid flow that comes only in fixed quantum steps.