Superfluid-to-insulator phase transition in a unitary Fermi gas

We study the properties of a dilute low-energy two-component Fermi gas. To this end, we approximate the Fermi gas by the Hubbard lattice Hamiltonian and solve it using the dynamical mean-field approximation. At unitarity, this approximation yields the value ξ0.44 for the ratio between the ground-state energy per particle of the interacting and free systems (EN=ξ EFG), in remarkable agreement with full quantum Monte Carlo simulations. Investigating the evolution of the system with temperature, we have found that below the critical temperature Tc, the system is a superfluid and the energy gap is decreasing monotonously. For temperatures above Tc, the system is an insulator and the corresponding energy gap is monotonously increasing.