Mechanical stability of a strongly interacting Fermi gas of atoms

A study was performed to show heuristically that the maximum inward force arising from attractive interactions in a two-state gas of atomic fermions is limited by quantum mechanics to a value less than the outward Fermi pressure. This idea was experimentally demonstrated by directly cooling a two-component Fermi gas of ⁶Li atoms to high degeneracy in an optical trap at magnetic fields near a Feshbach resonance. Imaging the cloud both in the trap and after an abrupt release, no evidence of instability was found. By measuring the relevant universal many-body parameter β, stability was quantitatively described.