Quantum walks in commensurate off-diagonal Aubry-Andr\'{e}-Harper model

TL;DR

This paper explores how quantum walks behave in a topologically nontrivial Aubry-Andre9-Harper lattice, revealing edge state effects, localization properties, and interaction influences on quantum dynamics.

Contribution

It provides a detailed analysis of quantum walk localization and edge state effects in the commensurate AAH model, including the impact of interactions on these phenomena.

Findings

Quantum walkers delocalize until strong periodic modulation.

Edge states' IPRs mainly determine localization.

Strong interactions enhance edge state 'repulsion' effects.

Abstract

Due to the topological nature of Aubry-Andr\'{e}-Harper (AAH) model, exotic edge states have been found existing in one-dimensional periodic and quasiperiodic lattices. In this article, we investigate continuous-time quantum walks of identical particles initially located on either edge of commensurate AAH lattices in detail. It is shown that the quantum walker is delocalized among the whole lattice until the strength of periodic modulation is strong enough. The inverse participation ratios (IPRs) for all of the eigenstates are calculated. It is found that the localization properties of the quantum walker is mainly determined by the IPRs of the topologically protected edge states. More interestingly, the edge states are shown to have an exotic `\emph{repulsion}' effect on quantum walkers initiated from the lattice sites inside the bulk. Furthermore, we examine the role of nearest-neighbour interaction on the quantum walks of two identical fermions. Clear enhancement of the `\emph{repulsion}' effect by strong interaction has been shown.