Absence of superdiffusion in the quasiperiodic spin chain at weak integrability breaking

TL;DR

This paper demonstrates that the Aubry-Andre-Harper model exhibits diffusive spin transport at high temperatures under weak integrability breaking, contradicting previous claims of superdiffusion which are shown to be finite-size effects.

Contribution

The study clarifies the nature of spin transport in the model, showing it is diffusive rather than superdiffusive, correcting prior misconceptions.

Findings

The model exhibits diffusive spin transport at high temperatures.

Superdiffusion observed previously is a finite-size effect.

The results are based on both new and unpublished data.

Abstract

There has been interest in the spin transport properties of the Aubry-Andre-Harper model at high temperatures under weak integrability breaking, in particular for small interactions or small fields. We present old unpublished and new results that show that the model is diffusive, meaning that the claimed superdiffusion [1,2] is a finite-size effect.