Ketterle Group Reports Bose Einstein Condensation of Lithium Molecules

In a recent article in Physical Review Letters, Wolfgang Ketterle's group at MIT has described the process for creating diatomic molecules of 6Li atoms and then cooling them into the BEC state. The 6Li atoms are fermions, so this molecular BEC represents one extreme of the crossover from Bose-Einstein condensation of tightly-bound atom pairs to BCS superfluidity of Cooper pairs, a long-sought goal.

The molecular BEC was reached in several rather simple steps. In the case of 6Li, cooling the atoms at constant magnetic field near a Feshbach resonance creates an atom-molecule mixture in thermal equilibrium. For temperatures lower than the binding energy of the molecular state, an almost pure molecular gas forms, and lower temperatures yield the molecular BEC. The group now intends to use this molecular BEC to look for the BEC-BCS crossover by sweeping the magnetic field.

Details of this paper can be found at the PRL web site
Also see the announcement released by the university at