Ultrastable CO2 laser trapping of lithium fermions

We demonstrate an ultrastable CO2 laser trap that provides tight confinemen t of neutral atoms with negligible optical scattering and minimal laser-noi se-induced heating. Using this method, fermionic Li-6 atoms are stored in a 0.4 mK deep well with a Ile trap lifetime of 300 sec, consistent with a ba ckground pressure of 10(-11) Torr. To our knowledge, this is the longest st orage time ever achieved with an all-optical trap, comparable to the best r eported magnetic traps. [S0031-9007(99)09193-0].