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Condensate-free superfluid induced by frustrated proximity effect

par Nicolas Laflorencie - 20 juillet 2011

Toutes les versions de cet article : English , français

In a recent letter published in Phys. Rev. Lett. 107, 037203 (2011), Nicolas Laflorencie from LPT and Frédéric Mila from EPFL have shown that Bose-Einstein Condensation and Superfluidity may not appear simultaneously due to a frustrated proximity effect.

Since the discovery of superfluidity in ^4He and Landau’s phenomenological theory, the relationship between Bose condensation and superfluidity has been intensely debated. ^4He is known by now to be both superfluid and condensed at low temperature, and more generally, in dimension D\ge2, all superfluid bosonic models realized in experiments are condensed in their ground-state, the most recent example being provided by ultracold bosonic atoms trapped in an optical lattice. In this paper, it is shown that a 2D gas of bosons which is not condensed at T=0 can be achieved by populating a layer through a frustrated proximity effect from a superfluid reservoir. This condensate-free bosonic fluid is further shown to be a superfluid with incommensurate correlations.