All-optical production and transport of a large ${}^6$Li quantum gas in a crossed optical dipole trap

Abstract

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 $2S_{1/2}\to 3P_{3/2}$ laser cooling resulting in a high phase-space density of up to $3\times 10^{-4}$. This allows utilizing a large volume crossed optical dipole trap with a total power of $45\text{W}$, leading to high loading efficiency and $8\times 10^6$ trapped atoms. The same optical trapping configuration is used for rapid adiabatic transport over a distance of $25\text{cm}$ in $0.9\text{s}$, and subsequent evaporative cooling. With optimized evaporation we achieve a degenerate Fermi gas with $1.7\times 10^6$ atoms at a temperature of $60\text{nK}$, corresponding to $T/T_{\text{F}}=0.16\left(2\right)$. Furthermore, the performance is demonstrated by evaporation near a broad Feshbach resonance creating a molecular Bose-Einstein condensate of $3\times 10^5$ lithium dimers.