Asymmetric transport computations in Dirac models of topological insulators

TL;DR

This paper introduces a fast spectral method for calculating transport properties in 2D Dirac models of topological insulators, confirming quantized interface conductivity and analyzing topological protection of asymmetric transport.

Contribution

The paper develops a novel spectral discretization approach for volume integral equations to efficiently compute transport in Dirac models of topological insulators.

Findings

Quantized interface conductivity confirms transport asymmetry.

Transport is topologically protected against local perturbations.

Back-scattering can occur despite asymmetric transport protection.

Abstract

This paper presents a fast algorithm for computing transport properties of two-dimensional Dirac operators with linear domain walls, which model the macroscopic behavior of the robust and asymmetric transport observed at an interface separating two two-dimensional topological insulators. Our method is based on reformulating the partial differential equation as a corresponding volume integral equation, which we solve via a spectral discretization scheme. We demonstrate the accuracy of our method by confirming the quantization of an appropriate interface conductivity modeling transport asymmetry along the interface, and moreover confirm that this quantity is immune to local perturbations. We also compute the far-field scattering matrix generated by such perturbations and verify that while asymmetric transport is topologically protected the absence of back-scattering is not.