Phase diagram of bosons in two-color superlattices from experimental parameters

We study the zero-temperature phase diagram of a gas of bosonic Rb-87 atoms in two-color superlattice potentials starting directly from the experimental parameters, such as wavelengths and intensities of the two lasers generating the superlattice. In a first step, we map the experimental setup to a Bose-Hubbard Hamiltonian with site-dependent parameters through approximate band-structure calculations. In the second step, we solve the many-body problem using the density-matrix renormalization-group approach and compute observables such as energy gap, condensate fraction, maximum number fluctuations, and visibility of interference fringes. We study the phase diagram as function of the laser intensities s(2) and s(1) as control parameters and show that all relevant quantum phases, i.e., superfluid, Mott-insulator, and quasi-Bose-glass phase, and the transitions between them can be investigated through a variation of these intensities alone.