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Strange rotations
c'est froid!
Aimant

Strange rotations

Quantum whirlpools

Filling of a cryostat with liquid helium  ; CNRS Photothèque / Benoît RAJAU, LPEMA superfluid does not rotate like a classical liquid. When you make a container with a superfluid inside slowly rotate, the sides of the container rotate but the superfluid inside remains motionless in a relaxed state, which is its minimum energy fundamental state. A superfluid resists rotation the same way a superconductor resists the penetration of a magnetic field.

Over a certain rotation speed of the container, the superfluid starts to rotate but in a very peculiar way: identical whirlpools start overrunning the container. These whirlpools are the proof that a coherent quantum state exists where all atoms move together in the same way. This situation is identical to that of a type II superconductor, with the existence of whirlwinds called vortices, in the presence of a high magnetic field.

In superfluids, we can also create permanent currents that never stop, as in superconducting coils.

 

CNRSSociété Française de PhysiqueTriangle de la physique
Pied de pagehey ! C'est un bord arrondi ?
c'est froid!
CNRSSociété Française de PhysiqueTriangle de la physique