Critical Temperature and Thermodynamic Properties of Attractive Fermions

The unitarity regime of the BCS-BEC crossover can be realized by diluting a system of two-component lattice fermions with an on-site attractive interaction. We perform a systematic-error- free finite-temperature simulations of this system by diagrammatic determinant Monte Carlo. We report the data obtained on the Cray X1E ``Phoenix'' of the Oak Ridge National Laboratory. The critical temperature in units of Fermi energy is found to be $T_c / E_F = 0.152(7)$. We also report the behaviour of the thermodynamic functions, and discuss the issues of thermomentry of ultracold Fermi gases.