Ultracold Heteronuclear Fermi-Fermi Molecules

Spin mixtures of quantum-degenerate fermionic gases exhibit long lifetimes in the strongly-interacting regime near a Feshbach resonance. This has opened the door for numerous key experiments like the creation of Fermi-Fermi molecules, the realization of molecular BEC, the observation of a pairing gap and of superfluidity in a fermionic gas in the BEC-BCS cross-over region near a Feshbach resonance. We present the production of ${}^{6}\textrm{Li}$-${}^{40}\textrm{K}$ heteronuclear molecules based on our experimental platform for the production of a two-species mixture of quantum-degenerate Fermi gases [1]. We studied two s-wave Feshbach resonances between lithium and potassium at $155\,\mathrm{G}$ and $168\,\mathrm{G}$. By magnetic field sweeps we created about $4\times 10^{4}$ ${}^{6}\textrm{Li}$-${}^{40}\textrm{K}$ molecules at conversion efficiencies of up to $50\,\%$ [2]. With a Stern-Gerlach purification technique we are able to image molecules and atoms spatially separated from each other. We show an increased molecule lifetime close to resonance of more than 100 ms in the molecule-atom mixture.\newline [1] {M.~Taglieber \emph{et al.}, Phys. Rev. Lett. {\bf 100}, 010401 (2008).}\newline [2] {A.-C.~Voigt \emph{et al.}, Phys. Rev. Lett. {\bf 102}, 020405 (2009).}