Mechanical Stability of a Strongly-Interacting Fermi Gas of Atoms
  A strongly-attractive, two-component Fermi gas of atoms exhibits universal behavior and should be mechanically stable as a consequence of the quantum mechanical requirement of unitarity. This requirement limits the maximum attractive force to a value smaller than that of the outward Fermi pressure. To experimentally demonstrate this stability, we use all-optical methods to produce a highly degenerate, two-component gas of $^6$Li atoms in an applied magnetic field near a Feshbach resonance, where strong interactions are observed. We find that the gas is stable at densities far exceeding that predicted previously for the onset of mechanical instability. Further, we provide a temperature-corrected measurement of an important, universal, many-body parameter which determines the stability--the mean field contribution to the chemical potential in units of the local Fermi energy. 
M. E. Gehm, S. L. Hemmer, S. R. Granade, K. M. O'Hara, J. E. Thomas