  By using the diffusion Monte Carlo method we calculate the one- and two-body
density matrix of an interacting Fermi gas at T=0 in the BCS-BEC crossover.
Results for the momentum distribution of the atoms, as obtained from the
Fourier transform of the one-body density matrix, are reported as a function of
the interaction strength. Off-diagonal long-range order in the system is
investigated through the asymptotic behavior of the two-body density matrix.
The condensate fraction of fermionic pairs is calculated in the unitary limit
and on both sides of the BCS-BEC crossover.
