Atoms and molecules in lattices: Bose-Einstein condensates built on a shared vacuum

In optical lattices where each site is occupied in its lowest energy state by a superposition of zero, one, and two atoms, one can in a controllable manner convert the atomic pair into a molecule while retaining the vacuum and one-atom amplitudes. The microscopic quantum coherence on each site between the vacuum and the single molecule component leads to a macroscopically populated molecular condensate when the lattice is removed.