Historical research guide · 0639 · 1987
Quantized vortices in superfluid 3He
M. M. Salomaa · G. E. Volovik
In one minute
Set a container of superfluid helium-3 rotating and the whirlpools inside it cannot be any size they like: circulation comes in fixed quanta, and each quantum is a line defect threading the liquid. Mikko Salomaa and Grigory Volovik wrote the review of what the first five years of rotating-helium-3 experiments at the Low Temperature Laboratory in Helsinki had turned up, and their tool throughout is broken symmetry — which symmetries the ordered state gives up, because that is what fixes the kinds of defect the state can carry. In helium-3 the answer is a catalogue no other superfluid offers. In the A phase the vorticity can be carried by a smooth winding of the order parameter, so the vortex has no singular core at all and carries two flow quanta, and vortices with half a quantum of circulation are allowed as well. In the B phase the core is a small piece of matter in its own right — ferromagnetic, superfluid, parity-breaking — and it switches structure in a first-order transition the experiments see.
Connection
Chapter 5 reads the vacuum as a quantum fluid with structure, and superfluid helium-3 is the laboratory system where that reading can be checked defect by defect: the order parameter has enough internal symmetry to support the same kinds of object a field theory of the vacuum needs. Chapter 13 uses that correspondence directly, and the companion experiment at /library/stm-065e484325 counts vortices frozen in one at a time as an analogue of defect formation in the early universe.
From the source
The first measurements on vortices in rotating superfluid helium-3, carried out at the Low Temperature Laboratory of Helsinki University of Technology over the five years before this review, revealed vortex phenomena that are not observed in any other known superfluid.Abstract, first two sentences
The organising idea of the review is broken symmetry: applying the concept of broken symmetry to the ordered state is what determines which quantized vortex lines superfluid helium-3 can support.Abstract, third sentence
In the superfluid A phase vorticity can be supported by a continuous winding of the order parameter, which gives rise to continuous coreless vortices carrying two flow quanta rather than one.Abstract, fourth sentence
Novel vortices carrying a half-integer number of circulation quanta may also exist in helium-3 A, permitted by a combined symmetry of the superfluid state.Abstract, fifth sentence
In the superfluid B phase the vortices have a complicated core structure: the vortex-core matter is ferromagnetic and superfluid and displays broken parity, and the ferromagnetism of the core is observed in nuclear magnetic resonance experiments through a gyromagnetic effect.Abstract, sixth and seventh sentences
The calculated core structures exhibit an experimentally observed first-order phase transition, which the authors read as a change in the topology for flaring-out of the vortex singularity into higher dimensions — a topological identification that further suggests the transition manifests a spontaneous bifurcation of vorticity involving half-quantum vortices in helium-3 B, and the authors close by noting that these advances in quantum liquids are of general relevance to a wide range of fields beyond low-temperature physics.Abstract, eighth to tenth sentences
The way in
https://doi.org/10.1103/RevModPhys.59.533How to cite it
M. M. Salomaa, G. E. Volovik (1987) Quantized vortices in superfluid 3He doi:10.1103/RevModPhys.59.533