Exploring the phase diagram of a double-well optical lattice

Recent work in our group has demonstrated the creation and utility of a double-well optical lattice, consisting of a three-dimensional array of dynamically deformable lattice sites spanning the range from simple single wells to independent pairs of wells with variable barrier height and energy `tilt.' The lattice is occupied by atoms loaded from an initially Bose-condensed sample of $^{87}$Rb atoms. The various lattice parameters can be adjusted so as to create a stack of independent 2D lattices, or, in the sense of the so-called `two-leg ladder,' an array of chained double wells. We present preliminary investigations into the phase diagram of this system, which has been predicted to exhibit novel transitions between a half-filling/unit-filling Mott insulator and the superfluid phase as the chain couplings are varied.