Strongly-paired fermions: cold atoms and neutron matter

Abstract

Experiments in cold Fermi atoms can be tuned to probe strongly-interacting fluids very similar to the low-density neutron matter found in the crusts of neutron stars. In contrast to traditional superfluids and superconductors, matter in this regime is very strongly paired, with gaps of order the Fermi energy. We compute the T=0 equation of state and pairing gaps for cold atoms and low-density neutron matter as a function of the Fermi momentum times the scattering length (κFa). Results of Quantum Monte Carlo calculations show that the equations of state are very similar. The neutron matter pairing gap at low densities is found to be very large but, except at the smallest densities, significantly suppressed relative to cold atoms because of the finite effective range.