Bose-Einstein condensation, phase coherence, and two-fluid behavior in 4He

Phys Rev Lett. 2004 Apr 2;92(13):135302. doi: 10.1103/PhysRevLett.92.135302. Epub 2004 Apr 1.

Abstract

It is shown that the assumption that the many particle wave functions describing superfluid 4He have some phase coherence properties of correlated basis functions provides a new explanation of the link between Bose-Einstein condensation and two fluid behavior. This assumption also implies that the condensate fraction is proportional to the superfluid fraction, in agreement with experiment, and provides a simple quantitative explanation of the anomalous reduction in spatial order and liquid density, observed as the temperature is lowered in superfluid 4He.