Realization of fractional Chern insulators in the thin-torus limit with ultracold bosons

Topological states of interacting many-body systems are at the focus of current research due to the exotic properties of their elementary excitations. In this paper we suggest a realistic experimental setup for the realization of a simple version of such a phase. We show how delta-interacting bosons hopping on the links of a one-dimensional ladder can be used to simulate the thin-torus limit of the two-dimensional (2D) Hofstadter-Hubbard model at one-quarter magnetic flux per plaquette. Bosons can be confined to ladders by optical superlattices, and synthetic magnetic fields can be realized by laser-assisted tunneling. We show that twisted boundary conditions can be implemented, enabling the realization of a fractionally quantized Thouless pump. Using numerical density-matrix-renormalization-group calculations, we show that the ground state of our model is an incompressible symmetry-protected topological charge density wave phase at average filling rho = 1/8 per lattice site, related to the 1/2 Laughlin-type state of the corresponding 2D model.