Pairing and Superfluid Properties of Dilute Fermion Gases at Unitarity

We study the system of a dilute gas of fermions in 3-dimensions, with attractive interactions tuned to the unitarity point, using the non-perturbative Restricted Path Integral Monte Carlo (R-PIMC) method. The pairing and superfluid properties of this system are calculated at finite temperature. The total energy at very low temperature from our results agrees closely with that of previous ground-state Quantum Monte Carlo calculations. We identify the temperature $T^\ast\approx 0.70\epsilon_F$ below which pairing correlations develop, and estimate the critical temperature for the superfluid transition $T_c\approx 0.25\epsilon_F$ from a finite size scaling analysis of the superfluid density.