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Double-quantum vortex in superfluid He-3-A

Research output: Contribution to Journal/MagazineJournal articlepeer-review

  • R. Blaauwgeers
  • V. B. Eltsov
  • M. Krusius
  • J. J. Ruohio
  • Roch Schanen
  • G. E. Volovik
<mark>Journal publication date</mark>30/03/2000
Issue number6777
Number of pages3
Pages (from-to)471-473
Publication StatusPublished
<mark>Original language</mark>English


Linear defects are generic in continuous media(1). In quantum systems they appear as topological line defects which are associated with a circulating persistent current. In relativistic quantum field theories they are known as cosmic strings(2), in superconductors as quantized flux lines(3), and in superfluids(3,4) and low-density Bose-Einstein condensates(5) as quantized vortex lines. A conventional quantized vortex Line consists of a central core around which the phase of the order parameter winds by 2 pi n, while within the core the order parameter vanishes or is depleted from the bulk value. Usually vortices are singly quantized (that is, have n = 1). But it has been theoretically predicted that, in superfluid He-3-A, vortex lines are possible that have n = 2 and continuous structure, so that the orientation of the multicomponent order parameter changes smoothly throughout the vortex while the amplitude remains constant. Here we report direct proof, based on high-resolution nuclear magnetic resonance measurements, that the most common vortex line in He-3-A has n = 2. One vortex line after another is observed to form in a regular periodic process, similar to a phase-slip in the Josephson effect.