Superfluid fraction in disordered bosonic gases

Abstract

In this work, we study the behaviour of the superfluid fraction f of a bosonic system under the influence of a speckle potential. We start by introducing and defining f, and then we present the lower and upper bounds to f derived by A. Leggett for generic many-body systems. To benchmark our codes, we study first the case of a periodic optical potential, reproducing results that recently appeared in the literature. We continue by describing the particular kind of disordered potential we want to study, and how this is characterized. Finally, we compute the superfluid fraction as a function of the intensity of the disordered potential and the interaction strength between the bosons, and we compare our results to the two bounds in both 1D and 2D.