Sodium Bose-Einstein condensates in an optical lattice

The phase transition from a superfluid to a Mott insulator has been observed in a ²³Na Bose-Einstein condensate. A dye laser detuned ≈50.3em0exnm red of the Na 3²S→3²P1∕2 transition was used to form the three-dimensional optical lattice. The heating effects of the small detuning as well as the three-body decay processes constrained the time scale of the experiment. Certain lattice detunings were found to induce a large loss of atoms. These loss features were shown to be due to photoassociation of atoms to vibrational levels in the Na₂0.3em0ex(1)³Σg⁺ state.