Quantized Vortex Lattice in Rotating Superfluid Helium

Spin a bucket of ordinary liquid helium-4 fast enough below the lambda point and its superfluid component responds not with smooth rotation but by threading itself with an array of quantized vortex lines, each carrying exactly one quantum of circulation κ = h/m₄. This simulation integrates the real Hall–Vinen equation of motion for every line — Biot–Savart induction from every other vortex, wall images enforcing the container boundary, and mutual friction with the co-rotating normal-fluid component — so the array visibly self-organizes into the triangular Abrikosov-style lattice predicted by Feynman's rule for vortex density. Adjust the rotation rate to re-nucleate a denser or sparser array, adjust temperature to change how strongly mutual friction drags the lattice into order, and perturb it to watch the crystallization happen live.