Simulating bosonic Chern insulators in one-dimensional optical superlattices

TL;DR

This paper demonstrates how a one-dimensional optical superlattice with ultracold bosons can simulate bosonic Chern insulators, revealing rich topological phases and transitions in an interacting bosonic system.

Contribution

It introduces a method to realize bosonic Chern insulators in a 1D optical lattice and analyzes their topological properties and phase diagram.

Findings

Identification of topological phases with nonzero Chern number

Observation of topological phase transition from trivial to nontrivial insulators

Presence of gapless edge modes and topological pumping in the system

Abstract

We study the topological properties of an extended Bose-Hubbard model with cyclically modulated hopping and on-site potential parameters, which can be realized with ultracold bosonic atoms in a one-dimensional optical superlattice. We show that the interacting bosonic chain at half filling and in the deep Mott insulating regime can simulate bosonic Chern insulators with a topological phase diagram similar to that of the Haldane model of noninteracting fermions. Furthermore, we explore the topological properties of the ground state by calculating the many-body Chern number, the quasiparticle energy spectrum with gapless edge modes, the topological pumping of the interacting bosons, and the topological phase transition from normal (trivial) to topological Mott insulators. We also present the global phase diagram of the many-body ground state, which contains a superfluid phase and two Mott insulating phases with trivial (a zero Chern number) and nontrivial topologies (a nonzero Chern number), respectively.