Quantum degeneracy in a fermionic atom gas

Magnetic trapping and evaporative cooling were used to cool a million ⁴⁰K atoms below the Fermi temperature. Simultaneous evaporation of spin-mixed samples was used to overcome the lack of s-wave collisions between spin-polarized fermionic atoms at these ultralow temperatures. By releasing the gas from the magnetic trap and allowing it to expand, the energy and momentum distributions of this quantum degenerate were measured. Consistent with Fermi-Dirac (FD) quantum statistics, the total energy in the gas was higher than the classical expectation at the same temperature. Further, the momentum distribution was non-gaussian (non-classical) and also congruent with FD statistics.