Observation of Fermi pressure in a gas of trapped atoms

We report the attainment of simultaneous quantum degeneracy in a mixed gas of bosons (lithium-7) and fermions (Lithium-6). The Fermi gas has been cool ed to a temperature of 0.25 times the Fermi temperature by thermal collisio ns with the evaporatively cooled bosons. At this temperature, the spatial s ize of the gas is strongly affected by the Fermi pressure resulting from th e Pauli exclusion principle and gives clear experimental evidence for quant um degeneracy.