Tanʼs universal contact and collective oscillations of strongly interacting Fermi gases

We study strongly interacting two component Fermi gas near a Feshbach resonance. By using a ground state energy functional constructed based on asymptotic limits and Monte Carlo calculations, we calculate the contact, structure factor, and collective oscillation frequencies in the BCS–BEC crossover region. The calculated contact and structure factor show excellent agreements with recent experiments. We compare these results with a standard mean-field theory and find that the contact is proportional to the square of superfluid order parameter. Further, we present the chemical potential and the polytropic index in terms of homogeneous energy and the contact.

► We study strongly interacting Fermi gasses near a Feshbach resonance. ► We calculate the contact using two different approaches. ► We evaluate the structure factor using the calculated contact. ► We compare the calculated contact with experiments and other theoretical approaches in literature. ► We calculate collective excitations in the presence of harmonic trap.