Collisional cooling of ultra-cold atom ensembles using Feshbach resonances

We propose a new type of cooling mechanism for ultra-cold fermionic atom ensembles, which capitalizes on the energy dependence of inelastic collisions in the presence of a Feshbach resonance. We first discuss the case of a single magnetic resonance, and find that the final temperature and the cooling rate is limited by the width of the resonance. A concrete example, based on a $p$-wave resonance of $^{40}$K, is given. We then improve upon this setup by using both a very sharp optical resonance and a very broad magnetic resonance and show that one can reach temperatures competitive to those created by current technologies.