Probing topological phase transitions in Aubry-Andre-Harper model via high-harmonic generation

TL;DR

This paper investigates how high-harmonic generation (HHG) can be used to detect topological phase transitions in the Aubry-Andre-Harper model, revealing a strong dependence of harmonic yield on topological phases and symmetry-breaking effects.

Contribution

It demonstrates that HHG yield thresholds can serve as all-optical indicators of topological phases in the AAH model, including effects of chiral symmetry breaking.

Findings

Harmonic yield varies significantly between topologically trivial and nontrivial phases.

Thresholds in HHG can identify topological phase transitions.

Onsite potential influences edge state degeneracy and HHG enhancement.

Abstract

We study the high-harmonic generation in the Aubry-Andre-Harper (AAH) model. The modulating phase of the AAH model is used as a control parameter while preserving the chiral symmetry hosting the zero-energy edge states. The harmonic yield in a particular energy range exhibits a strong dependence on the control parameter with clear separation of the region of topologically trivial and nontrivial phases of the system. The threshold for the harmonic yield is found to serve as an all-optical tool for detecting topological phases. We extended our study with broken chiral symmetry by including the onsite potential. The introduction of the onsite potential lifts the degeneracy in the edge states, which affects the harmonic enhancement. Furthermore, it is also observed that the system's onsite strength can control the HHG yield.