Trapping and cooling of atoms became the workhorse of atomic physics in the last decades. On the other hand, molecular cooling and trapping remain challenging. Even less progress has been made in generation of cold mixtures of atoms and molecules, which opens many possibilities in physics and chemistry. Atom-molecule co-trapping offers orders of magnitude longer interrogation times as compared to molecular beam based methods, study of cold chemistry for especially slow processes, production of polyatomic molecules by photoassociation or Feshbach resonances and more. 

One of the most exciting prospects of cold mixtures is the application of sympathetic cooling, where cold atoms that are amenable to laser cooling can be used to collisionally cool molecules. We have co-decelerated and trapped a cold mixture of atomic Lithium and molecular Oxygen, as a first step towards studies of cold atom-molecule collisions at low temperatures, as well as application of sympathetic cooling. The Oxygen molecules are produced by a supersonic expansion, and the Lithium atoms are entrained into the beam by laser ablation prior to deceleration. We use the Zeeman interaction in order to load both the atoms and the molecules into our moving magnetic trap decelerator, where they are slowed down. The decelerated mixture is loaded into a quadrupole trap, produced by permanent magnets, where we measure background-limited lifetime of over 500 ms for both species.

We estimate 10^9 trapped Oxygen molecules, which is the largest ensemble of trapped molecules achieved to date. Our work is concentrated on improving the Lithium entrainment technique, in order to reach the desired conditions to perform sympathetic cooling.