  We study topological properties of the Bose-Hubbard model with repulsive
interactions in a one-dimensional optical superlattice. We find that the Mott
insulator states of the single-component (two-component) Bose-Hubbard model
under fractional fillings are topological insulators characterized by a nonzero
charge (or spin) Chern number with nontrivial edge states. For ultracold atomic
experiments, we show that the topological Chern number can be detected through
measuring the density profiles of the bosonic atoms in a harmonic trap.
