Weakly interacting Bose gases in optical lattices: a theoretical scenario to test London's hypothesis

by Dr Fernanda Pinheiro (Institute for Biological Physics, University of Cologne)

Tuesday 23 Nov 2010, 11:00 → 12:00 Europe/Stockholm

A5:1041 (OBS!)

After the discovery of the superfluid behavior of Helium-II, in 1938, London postulated that the phenomena of superfluidity was a manifestation of the Bose-Einstein condensation. Since then this statement is usually assumed as valid, as superfluid and condensation properties of many systems are very commonly studied together, but so far it still remains without a general theoretical proof. In this presentation I will show the results of the study of Bose-Einstein condensation and superfluidity in a ring-shaped 1D periodic potential which undergoes rotation. Here the phenomena of superfluidity is characterized in terms of an inertial parameter, and the approach used allows for the study of the superfluid fraction without assumptions regarding the condensate mode. Both condensate and superfluid fractions are compared, and the properties of the zero temperature phase-diagrams are also considered. The results indicate that for this system condensate and superfluid fractions are quite unrelated in terms of parameter values, suggesting, thus, that even for dilute gases the interchange of superfluid and condensate fractions should be considered more carefully.