UltrastableCO2Laser Trapping of Lithium Fermions

We demonstrate an ultrastable ${\mathrm{CO}}_2$ laser trap that provides tight confinement of neutral atoms with negligible optical scattering and minimal laser-noise-induced heating. Using this method, fermionic ${}^6\mathrm{Li}$ atoms are stored in a 0.4 mK deep well with a $1/e$ trap lifetime of 300 sec, consistent with a background pressure of ${10}^{-11\mathrm{}}\mathrm{Torr}$. To our knowledge, this is the longest storage time ever achieved with an all-optical trap, comparable to the best reported magnetic traps.