Two-stage magneto-optical trapping and narrow-line cooling of Li-6 atoms to high phase-space density

Abstract

We report an experimental study of peak and phase-space density of a two-stage magneto-optical trap (MOT) of Li6 atoms, which exploits the narrower 2S1/2→3P3/2 ultraviolet (UV) transition at 323 nm following trapping and cooling on the more common D2 transition at 671 nm. The UV MOT is loaded from a red MOT and is compressed to give a high phase-space density up to 3×10-4. Temperatures as low as 33μK are achieved on the UV transition. We study the density limiting factors and in particular find a value for the light-assisted collisional loss coefficient of 1.3±0.4×10-10 cm3/s for low repumping intensity.