Two-stage magneto-optical trapping and narrow-line cooling ofLi6atoms 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 $^{6}\mathrm{Li}$ atoms, which exploits the narrower $2{S}_{1/2}\ensuremath{\rightarrow}3{P}_{3/2}$ 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 $3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. Temperatures as low as $33\phantom{\rule{0.16em}{0ex}}\ensuremath{\mu}\mathrm{K}$ 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 $1.3\ifmmode\pm\else\textpm\fi{}0.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}$ ${\mathrm{cm}}^{3}$/s for low repumping intensity.