Breakdown of topological Thouless pumping in the strongly interacting regime

TL;DR

This paper investigates how strong interactions affect topological Thouless pumping, revealing conditions for its breakdown and novel interaction-induced phenomena, thus advancing understanding of topological phase stability.

Contribution

It provides a systematic analysis of the stability and breakdown mechanisms of topological Thouless pumping under strong interactions, highlighting symmetry changes and edge effects.

Findings

Symmetry protection can break down due to interactions, causing pump failure.

Edge density profiles reveal interaction effects even when bulk pumping remains robust.

Interaction effects can induce phases analogous to Weyl semimetals in topological pumping.

Abstract

We elucidate the mechanism for instability of topological Thouless pumping in strongly interacting systems from a viewpoint of symmetry-protected topological phases. If the protecting symmetries of the underlying topological phases change between noninteracting fermions and a bosonic system in the strong coupling limit, the symmetry protection argument enforces a gap closing and thereby predicts a breakdown of the topological pumping. We also demonstrate that, even in the weakly interacting regime where the bulk topological pumping is still robust, the interaction effects manifest themselves in the edge density profiles, leading to a unique feature of the pumping in open boundary conditions. Furthermore, an extension of the above results indicates that an analog of an interaction-induced phase of Weyl semimetals can be realized in the setup of the topological pumping. Our results provide a systematic understanding for the stability of topological pumping against strong interactions, to which the conventional perturbative argument cannot be applied.