Generalized criterion for stability of superflow past an obstacle

Yusuke Kato, Shohei Watabe

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)


We propose a new criterion of stability or instability of one-directional superflow of Bose condensates. In d-dimensional condensates with steady superflow, spectral function rho(r,ω=∑ l|〈l|n̂ (r)| g〉| 2 δ (ω-E l+E g) of the local density n̂(r) at the critical velocity behaves as ρ(r,ω)∝ ω β with β<d at low ω while ρ(r,ω)∝ ω d below the critical velocity. We confirm the validity of our criterion within the Gross-Pitaevskii-Bogoliubov theory. In the presence of a penetrable repulsive potential, β is given by d-2 at the critical velocity, where gray-soliton-phonon emission leads to the breakdown of superfluidity. In the case of the Landau instability in spatially uniform systems, on the other hand, β=-1/3,1/3,1 for d=1,2,3, respectively.

Original languageEnglish
Pages (from-to)92-98
Number of pages7
JournalJournal of Low Temperature Physics
Issue number1-2
Publication statusPublished - 2010 Jan
Externally publishedYes


  • BEC
  • Density fluctuation
  • Landau instability
  • Soliton emission
  • Spectral function
  • Superfluidity

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics
  • Materials Science(all)
  • Condensed Matter Physics


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