Hybrid skin-topological effect in non-Hermitian checkerboard lattices with large Chern numbers

TL;DR

This paper investigates non-Hermitian topological phases and hybrid skin-topological effects in checkerboard lattices with large Chern numbers, revealing new physical mechanisms and potential for experimental realization in photonic systems.

Contribution

It introduces a tunable non-Hermitian checkerboard lattice supporting hybrid skin-topological effects and uncovers a novel scattering mechanism linked to corner-induced edge channel interactions.

Findings

Observation of corner skin effects with $C_4$ or $C_2$ symmetry

Identification of a new scattering mechanism between chiral edge channels

Large Chern number enables diverse non-Hermitian topological states

Abstract

Non-Hermitian topology provides a research frontier for exploring topological phenomena, revealing novel topological effects and driving the development of emergent materials and platforms. Here, we explore the non-Hermitian Chern insulator phases and the hybrid skin-topological effects in checkerboard lattices with synthetic gauge fluxes. Such lattices can be realized in integrated silicon photonic nanocircuits and microresonators as well as in arrays of evanescently coupled helical optical waveguides. With a simple and tunable design, the system is found to support non-Hermitian hybrid skin topological effects, exhibiting corner skin effects when the lattice symmetry either $C_4$ or $C_2$. An unconventional physical mechanism is revealed as the origin of such a transition which is connected to the corner-induced scattering between the multiple chiral edge channels. These properties are enabled by the large Chern number and the rich non-Hermitian topological edge states in our system, revealing the diverse non-Hermitian topological bulk-boundary correspondence. Our design offers excellent controllability and experimental feasibility, making it appealing for studying non-Hermitian topological phenomena.