Effects of Disorder On Thouless Pumping In Higher-Order Topological Insulators

TL;DR

This paper studies how random disorder affects higher-order Thouless pumping in a topological insulator model, revealing that strong disorder can break quantized charge transport despite localized eigenstates, due to delocalized Floquet states.

Contribution

It provides a detailed analysis of disorder effects on higher-order topological pumping, highlighting the role of Floquet states in maintaining quantized transport under disorder.

Findings

Quantized charge transport breaks down under strong disorder.

Delocalized Floquet states enable charge transport despite eigenstate localization.

Disorder induces a phase transition from topological to trivial pumping.

Abstract

We investigate the effects of random onsite disorder on higher-order Thouless pumping of noninteracting fermionic Benalcazar-Bernevig-Hughes (BBH) model. The interplay of disorderinduced topological phase transition and delocalization-localization transition is extensively explored. The higher-order Thouless pumping is characterized by the quantized corner-to-corner charge transport and nonzero Chern number, and the delocalization-localization transition is analyzed by utilizing both inverse participation ratio and energy-level statistics. The results show that the quantized corner-to-corner charge transport is broken in the strong disorder, where the instantaneous bulk energy gap is closed due to effects of disorder. While, although the instantaneous eigenstates are localized, the charge transport remains quantized. This is attributed to delocalized Floquet states caused by the periodic driving. Furthermore, the phase transition from the quantized charge transport to topologically trivial pumping is accompanied by the disorder-induced delocalization-localization transition of Floquet states.