Observation of Bose-Einstein Condensation of Molecules

We have observed Bose-Einstein condensation of molecules. When a spin mixture of fermionic ⁶Li atoms was evaporatively cooled in an optical dipole trap near a Feshbach resonance, the atomic gas was converted into ⁶Li₂ molecules. Below 600 nK, a Bose-Einstein condensate of up to 900 000 molecules was identified by the sudden onset of a bimodal density distribution. This condensate realizes the limit of tightly bound fermion pairs in the crossover between BCS superfluidity and Bose-Einstein condensation.