Anomalous condensate fluctuations in strongly interacting superfluids

We show that the condensate occupation of a superfluid Bose liquid quite ge nerally exhibits anomalously large fluctuations at finite temperatures T no t equal 0. In three dimensions, the variance <delta (N) over cap(0)(2)> of the number (N) over cap(0) of particles in the condensate scales nonlinearl y with volume V like (TV4/3)-V-2 at low T, generalizing the result obtained by Giorgini, Pitaevskii, and Stringari for a weakly interacting Bose gas. In two dimensions there is only a quasicondensate whose fluctuations are of the same order as the mean value.