1-D Mott insulator transition of a Bose-Einstein condensate

We experimentally demonstrate the superfluid to one-dimensional Mott-insulator transition of a $^{87}$Rb Bose-Einstein condensate. In the experiment, we apply a one-dimensional optical lattice, formed by two laser beams with a wavelength of 852~nm, to a three dimensional BEC in a shallow trap. We use Kapitza-Dirac scattering to precisely determine the depth of the optical lattice without knowledge of its exact geometry. It is found that the one-dimensional Mott insulator state is reached at a lattice depth of 30 recoil energies. We further study behavior specific to the one-dimensional case, including interference between pancake BECs in separate wells and dephasing behavior at the transition between the superfluid and Mott insulator states.