Unitary Fermi gas in a harmonic trap

systems in the size range N 10 4 –1 0 6 are now well explored, but the small-N limit is also of great interest for optical lattices. In this work, we investigate the properties of small systems of trapped fermionic atoms using the Green’s function Monte Carlo GFMC technique that has been successful in the study of the homogeneous gas 8. Small systems are in some ways more challenging because simplifications that follow from translational invariance are not present. Our main goal here is to see how the bulk behavior evolves as a function of the number of atoms, and to provide benchmark ab initio results to test other theoretical methods. The Hamiltonian for interacting atoms in a spherical harmonic trap is given by