Effect of finite range interactions on roton mode softening in a multi-component BEC

Abstract

We consider the Gross-Pitaevskii model of a Bose–Einstein Condensate (BEC) for single-component and multi-component BEC. The pseudopotential for s-wave scattering between atoms is taken to be of a width of the order of the s-wave scattering length. Such an interaction giving rise to a roton minimum in the spectrum of elementary excitations of a single-component BEC is well known. However, softening roton modes take us into the strongly interacting BEC regime where three body losses occur. We study the roton mode softening for a multi-component BEC. We show that by increasing the number of components of a multi-component BEC, the roton mode can be softened at a progressively lower value of the gas parameter (a 3 n), thus reducing the three body losses.