Quantum Fluids

Observing peculiar vortices

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Science  13 Jan 2017:
Vol. 355, Issue 6321, pp. 144
DOI: 10.1126/science.355.6321.144-b

When a vessel filled with a superfluid is rotated, the superfluid, instead of moving with the vessel the way water would, develops an array of whirlpools called vortices. The flow around a vortex is “quantized,” characterized by discrete, integer numbers. It has long been suspected that in a particular kind of superfluid—3He at very low temperatures—it would be possible to observe vortices that are associated with half-integer numbers. Autti et al. observed the signature of these half-quantum vortices (HQVs) in the nuclear magnetic resonance (NMR) spectra of superfluid 3He confined in a porous medium. Pairs of HQVs caused the appearance of an additional NMR peak, whose position and dependence on the various parameters were consistent with theoretical expectations.

Phys. Rev. Lett. 117, 255301 (2016).

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