Coherent laser radiation allows dissipative cooling of diluted atomic gases to the temperatures of several magnetic field, or high power laser beams far detuned from atomic resonances. Simultaneous trapping of multiple laser-cooled atomic species is a necessary step toward synthesis of ultra-cold stable, polar molecules. Such molecules can be used to study new dipolar quantum superfluids, as building blocks in scalable quantum computing schemes, and as sensitive probes of fundamental physics.
We choose lithium (Li) and ytterbium (Yb) atoms for our experiment. Both Li and Yb possess stable bosonic and fermionic isotopes that have been laser cooled, trapped, and brought to quantum degeneracy in single species experiments. A large electric dipole moment in the molecular ground state allows studies of strongly dipolar quantum gases, and makes Li-Yb a promising candidate for a sensitive electron EDM measurement.
We achieve simultaneous cooling and trapping of lithium and ytterbium using standard magnetooptical traps (MOTs). Further the atoms are transferred to a virtually conservative trap (far offresonant optical dipole trap). We routinely obtain ~1 million optically trapped atoms of each species, at temperatures of about 100 μK. We use Li-Yb mixture for study of its collisional stability; furthermore we observe thermalization of the mixture that allows us to extract collisional crosssection of ultra-cold Li and Yb atoms.