Analogs of quantum Hall effect edge states in photonic crystals

TL;DR

This paper demonstrates that photonic crystals with Faraday-effect media can host unidirectional, chiral edge states analogous to quantum Hall effect electronic states, which are robust against disorder and backscattering.

Contribution

It provides explicit calculations showing the existence of photonic edge states that mimic quantum Hall edge states using time-reversal-symmetry-breaking media.

Findings

Photonic crystals can support unidirectional edge modes.

These edge states are immune to backscattering and disorder.

The Berry curvature in photonic bands is analogous to magnetic fields in QHE.

Abstract

"Photonic crystals" built with time-reversal-symmetry-breaking Faraday-effect media can exhibit "chiral" edge modes that propagate unidirectionally along boundaries across which the Faraday axis reverses. These modes are precise analogs of the electronic edge states of quantum Hall effect (QHE) systems, and are also immune to backscattering and localization by disorder. The "Berry curvature" of the photonic bands plays a role analogous to that of the magnetic field in the QHE. Explicit calculations demonstrating the existence of such unidirectionally-propagating photonic edge states are presented.