---
res:
  bibo_abstract:
  - Owing to thermal fluctuations, two-dimensional (2D) systems cannot undergo a conventional
    phase transition associated with the breaking of a continuous symmetry1. Nevertheless
    they may exhibit a phase transition to a state with quasi-long-range order via
    the Berezinskii–Kosterlitz–Thouless (BKT) mechanism2. A paradigm example is the
    2D Bose fluid, such as a liquid helium film3, which cannot condense at non-zero
    temperature although it becomes superfluid above a critical phase space density.
    The quasi-long-range coherence and the microscopic nature of the BKT transition
    were recently explored with ultracold atomic gases4,5,6. However, a direct observation
    of superfluidity in terms of frictionless flow is still missing for these systems.
    Here we probe the superfluidity of a 2D trapped Bose gas using a moving obstacle
    formed by a micrometre-sized laser beam. We find a dramatic variation of the response
    of the fluid, depending on its degree of degeneracy at the obstacle location.@eng
  bibo_authorlist:
  - foaf_Person:
      foaf_givenName: Rémi
      foaf_name: Desbuquois, Rémi
      foaf_surname: Desbuquois
  - foaf_Person:
      foaf_givenName: Lauriane
      foaf_name: Chomaz, Lauriane
      foaf_surname: Chomaz
  - foaf_Person:
      foaf_givenName: Tarik
      foaf_name: Yefsah, Tarik
      foaf_surname: Yefsah
  - foaf_Person:
      foaf_givenName: Julian
      foaf_name: Leonard, Julian
      foaf_surname: Leonard
      foaf_workInfoHomepage: http://www.librecat.org/personId=b75b3f45-7995-11ef-9bfd-9a9cd02c3577
  - foaf_Person:
      foaf_givenName: Jérôme
      foaf_name: Beugnon, Jérôme
      foaf_surname: Beugnon
  - foaf_Person:
      foaf_givenName: Christof
      foaf_name: Weitenberg, Christof
      foaf_surname: Weitenberg
  - foaf_Person:
      foaf_givenName: Jean
      foaf_name: Dalibard, Jean
      foaf_surname: Dalibard
  bibo_doi: 10.1038/nphys2378
  bibo_issue: '9'
  bibo_volume: 8
  dct_date: 2012^xs_gYear
  dct_isPartOf:
  - http://id.crossref.org/issn/1745-2473
  - http://id.crossref.org/issn/1745-2481
  dct_language: eng
  dct_publisher: Springer Nature@
  dct_title: Superfluid behaviour of a two-dimensional Bose gas@
...