Superfluid mixture of a Bose-Einstein condensate and a crossover superfluid

In this presentation, I discuss the influence of Boson-fermion interactions in a superfluid mixture consisting of a weakly interacting Bose-Einstein condensate and a fermionic superfluid along BEC-BCS crossover. Within random phase approximation, we calculate how the sound velocity changes with the inter-species interactions; the results are consistent with the analytic calculation in hydrodynamic regime. We further calculate the dynamic structure factor in this superfluid mixture which can be measured using Bragg spectroscopy. Relevance to the recent experiments on superfluid mixture will be commented.