Conversion of an Atomic Fermi Gas to a Long-Lived Molecular Bose Gas

We have converted an ultracold Fermi gas of ${}^6\mathrm{L}\mathrm{i}$ atoms into an ultracold gas of ${}^6\mathrm{L}\mathrm{i}_2$ molecules by adiabatic passage through a Feshbach resonance. Approximately $1.5\times {10}^5$ molecules in the least-bound, $v=38$, vibrational level of the $X^1{\Sigma }_g^{+}$ singlet state are produced with an efficiency of 50%. The molecules remain confined in an optical trap for times of up to 1 s before we dissociate them by a reverse adiabatic sweep.