We report an experimental study of peak and phase-space density of a two-stage magneto-optical trap (MOT) of 6 Li atoms, which exploits the narrower 2S 1/2 → 3P 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 × 10 −4 . Temperatures as low as 33 μK 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 cm 3 /s for low repumping intensity.

We report on an efficient production scheme for a large quantum degenerate sample of fermionic lithium. The approach is based on our previous work on narrow-line 2S 1/2 → 3P 3/2 laser cooling resulting in a high phase-space density of up to 3 × 10 −4 . This allows utilizing a large volume crossed optical dipole trap with a total power of 45 W, leading to high loading efficiency and 8 × 10 6 trapped atoms. The same optical trapping configuration is used for rapid adiabatic transport over a distance of 25 cm in 0.9 s, and subsequent evaporative cooling. With optimized evaporation we achieve a degenerate Fermi gas with 1.7 × 10 6 atoms at a temperature of 60 nK, corresponding to T /TF = 0.16 (2). Furthermore, the performance is demonstrated by evaporation near a broad Feshbach resonance creating a molecular Bose-Einstein condensate of 3 × 10 5 lithium dimers.

No abstract