Fractional Chern Insulator of Hard-Core Bosons in Topological Flat Bands

We study a two-dimensional lattice model of hard-core bosons by density matrix renormalization group and exact diagonalization methods. At low filling $\nu=1/2$, Abelian fractional quantum Hall (FQH) states emerge with signatures of a two-fold ground-state degeneracy on a torus and a nonzero topological entanglement entropy (TEE) $\gamma=-\ln{\sqrt{2}}$. At filling $\nu=2/3$, more exotic non-Abelian FQH states may emerge with a three-fold ground-state degeneracy and a TEE $\gamma=-\ln{2}$. The ($C$+1)-fold degenerate ground states are found to exhibit a nonzero Chern number $C$ at filling $\nu=C/(C+1)$. The system is topologically trivial at filling $\nu=1$, characterized by a symmetry-breaking density-wave order in the thermodynamic limit.