Onset of Fermi Degeneracy in a Trapped Atomci Gas

摘要

An evaporative cooling strategy that uses a two-component Fermi gas was employed to cool a magnetically trapped gas of 7×10~5 40~K atoms to 0.5 of the Fermi temperature T_f. In this temperature regime, where the state occu- pation at the lowest energies has increased from essentially zero at high temperatures to nearly 60 percent, quantum degeneracy was observed as a barrier to evaporative cooling and as a modification of the thermodynamics.