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

TL;DR

This paper presents an efficient method for producing and transporting a large quantum degenerate Fermi gas of lithium-6 atoms using a high-power crossed optical dipole trap, enabling rapid transport and evaporative cooling to achieve quantum degeneracy and molecular BEC.

Contribution

The authors demonstrate a novel integrated approach combining laser cooling, high-power optical trapping, rapid transport, and evaporative cooling to produce large quantum degenerate lithium-6 samples and molecular BECs.

Findings

Achieved a quantum degenerate Fermi gas with 1.7 million atoms at 60 nK.

Successfully transported atoms over 25 cm in 0.9 s using the same optical trap.

Created a molecular Bose-Einstein condensate of lithium dimers near a Feshbach resonance.

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}\rightarrow 3P_{3/2} $ laser cooling resulting in a high phase-space density of up to $3\times10^{-4}$. This allows utilizing a large volume crossed optical dipole trap with a total power of $45\,\textrm{W}$, leading to high loading efficiency and $8\times10^6$ trapped atoms. The same optical trapping configuration is used for rapid adiabatic transport over a distance of $25\,\textrm{cm}$ in $0.9\,\textrm{s}$, and subsequent evaporative cooling. With optimized evaporation we achieve a degenerate Fermi gas with $1.7\times 10^{6}$ atoms at a temperature of $60 \, \textrm{nK}$, 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 $3\times10^5$ lithium dimers.