Rapid sympathetic cooling to Fermi degeneracy on a chip

Neutral fermions present new opportunities for testing models of many-body quantum systems, realizing precision atom interferometry, producing ultra-cold molecules, and investigating fundamental forces. However, since they were first observed(1), quantum degenerate Fermi gases ( DFGs) have continued to be challenging to produce, and have been realized in only a handful of laboratories(2-10). In this letter, we report the production of a DFG using a simple apparatus based on a microfabricated magnetic trap. Similar approaches applied to Bose-Einstein condensation of Rb-87 ( refs 11,12) have accelerated evaporative cooling and eliminated the need for multiple vacuum chambers. We demonstrate sympathetic cooling for the first time in a microtrap, and cool K-40 to Fermi degeneracy in just six seconds-faster than has been possible in conventional magnetic traps. To understand our sympathetic cooling trajectory, we measure the temperature dependence of the K-40-Rb-87 cross-section and observe its Ramsauer-Townsend reduction.