Topological bands with Chern number C=2 by dipolar exchange interactions

TL;DR

This paper proposes a method to realize topological bands with Chern number 2 using dipolar interactions in polar molecules trapped in optical lattices, offering a platform for exploring fractional Chern insulators.

Contribution

It demonstrates the creation of topological band structures with high Chern numbers via dipolar exchange interactions in optical lattices, including flat bands suitable for fractional Chern insulators.

Findings

Topological bands with C=2 on square lattices.

Rich topological band structures on honeycomb lattices.

Robustness against missing molecules and flat bands for fractional states.

Abstract

We demonstrate the realization of topological band structures by exploiting the intrinsic spin-orbit coupling of dipolar interactions in combination with broken time-reversal symmetry. The system is based on polar molecules trapped in a deep optical lattice, where the dynamics of rotational excitations follows a hopping Hamiltonian which is determined by the dipolar exchange interactions. We find topological bands with Chern number $C=2$ on the square lattice, while a very rich structure of different topological bands appears on the honeycomb lattice. We show that the system is robust against missing molecules. For certain parameters we obtain flat bands, providing a promising candidate for the realization of hard-core bosonic fractional Chern insulators.