Superfluid to Mott-insulator transition in a 1D optical lattice

Abstract Bose-Einstein condensates of sodium atoms are transferred into one-dimensional optical lattice potentials, formed by two laser beams with a wavelength of 1064 nm, in a shallow optical trap. The phase coherence of the condensate in the lattice potential is studied by changing the lattice depth. A qualitative change in behavior of the BEC is observed at a lattice depth of ~13.7 E r , where the quantum gas undergoes a transition from a superfluid state to a state that lacks well-to-well phase coherence.