Physics (Internal)

CANCELLED: TBA

This event is part of the Condensed Matter Theory Seminar Series.

ABSTRACT: Landau in his classic 1941 paper argued that the flow of a superfluid at speeds greater than the (Landau) critical velocity destroys superfluidity, and conversely, that the existence of such a critical velocity is necessary for superfluidity. As this talk will show, this criterion is neither necessary nor sufficient. Rather, if the Landau criterion is violated the superfluid mass density becomes smaller than the total mass density. After a discussion of the fundamentals of superfluidity and the superfluid mass density, this talk will discuss the Landau criterion in the context of various superfluids including an explicit model of the weakly interacting Bose gas.