Z2 Topological insulator of ultra cold atoms in bichromatic optical lattices

TL;DR

This paper studies how a strong bichromatic deformation affects the $\

Contribution

It demonstrates the robustness of the $\

Findings

Topological character remains stable under certain perturbations

Lowest band can become trivial while higher bands stay protected

Robustness depends on deformation strength

Abstract

We investigate the effect of a strong bichromatic deformation to the $\mathbb{Z}_{2}$ topological insulator in a fermionic ultracold atomic system proposed by B. B\'eri and N. R. Cooper, Phys.Rev.Lett. {\bf 107}, 145301 (2011). Large insulating gap of this system allows for examination of strong perturbations. We consider bichromatic perturbation along all axes on a triangular optical lattice. We find that $\mathbb{Z}_{2}$ topological character of the system is robust up to a certain depth of the deformation. The lowest band can become topologically trivial while the lowest two bands are always protected.