Nondegenerate two-way edge channels of plasmons in networks

Abstract

An effective one-dimensional channel is formed at the periphery of a two-dimensional electron gas by electronic edge states. Robust edge states with suppressed dissipation arise from the Landau quantization in a strong magnetic field, and propagation through an edge channel formed by these states is one-way. In general, two-way edge channels rather than one-way ones have more advantages for applications and are the main topic of topological insulators. However, two-way edge channels of these are degenerate in their energies, which causes backscattering and dissipation. Here, we show that excited states in networks composed of capacitively coupled integer quantum Hall systems exhibit macroscopic two-way edge channels with different energies. Theoretical results are derived on the basis of two known effects; each system has plasmonic excitations known as edge magnetoplasmons, and the chirality of each system is diverted only locally by the capacitive interaction between nearest-neighbor systems. Because of the simplicity of the model, various extensions from regular networks to more complicated higher-dimensional networks are possible. The networks provide an ideal platform to test the functionality of plasmonic one-dimensional edge channels and suggest a dynamical model of fractional Quantum Hall systems.