Missing link between the 2D Quantum Hall problem and 1D quasicrystals

TL;DR

This paper establishes a direct link between 2D Quantum Hall topological properties and 1D quasicrystals through the Fibonacci-Hall model, enabling computation of Chern numbers and revealing Lifshitz transitions.

Contribution

It introduces the Fibonacci-Hall model as a novel connection between 1D quasicrystals and 2D topological insulators, allowing calculation of topological invariants from geometric parameters.

Findings

Chern numbers can be computed for quasicrystal approximants.

Lifshitz transitions correspond to changes in Chern numbers and edge states.

The method can be extended to higher-dimensional quasicrystals.

Abstract

This paper discusses a connection between two important classes of materials, namely quasicrystals and topological insulators as exemplified by the Quantum Hall problem. It has been remarked that the quasicrystal ``inherits" topological properties from the 2D Quantum Hall model. We show this explicitly by introducing the Fibonacci-Hall model as a link between a 1D quasicrystal and the magnetic problems. We show here how Chern numbers for bands in periodic approximants of quasicrystals can be computed, along with gap labels. The Chern numbers are thus seen as a consequence of a flux parameter $\phi^S$ induced by the geometry of winding in 2D space of the quasicrystal. We show the existence of lines of Lifshitz transitions in the phase space of the model. These are marked by change of Chern number and disappearance of edge states. The proposed extrapolation method can be generalized to higher dimensional 2D and 3D quasicrystals, where higher order Chern numbers could be computed, and related to experimentally measurable transport quantities.