Ground-state properties of 1D Hubbard model in optical superlattice

We study the ground-state properties of a cold Fermi gas trapped in a one-dimensional optical superlattice with periodically modulated lattice potentials. By applying the density matrix renormalization group method to the Hubbard model with harmonic confinement, we compute the density profile and the spin correlation function for several different choices of superlattice potential. The ground state is characterized by the coexistence phase with the metallic and several types of Mott-insulating domains. It is shown that the spin correlation can be enhanced between the two spatially separated Mott-insulating domains