Exact Solutions Disentangle Higher-Order Topology in 2D Non-Hermitian Lattices
Abstract
We report the exact closed-form solutions for higher-order topological states as well as explicit energy-spectrum relationships in two-dimensional (2D) non-Hermitian multi-orbital lattices with generalized boundary conditions. These analytical solutions unequivocally confirm that topological edge states in a 2D non-Hermitian system which feature point-gap topology must undergo the non-Hermitian skin effect along the edge. Under double open boundary conditions, the occurrence of the non-Hermitian skin effect for either topological edge states or bulk states can be accurately predicted by our proposed winding numbers. We unveil that the zero-energy topological corner state only manifests itself on a corner where two nearby gapped edge states intersect, and thus can either disappear completely or strengthen drastically due to the non-Hermitian skin effect of gapped topological edge states. Our analytical results offer direct insight into the non-Bloch band topology in two or higher dimensions and trigger experimental investigations into related phenomena such as quadrupole topological insulators and topological lasing.
Keywords
Cite
@article{arxiv.2410.15763,
title = {Exact Solutions Disentangle Higher-Order Topology in 2D Non-Hermitian Lattices},
author = {Lingfang Li and Yating Wei and Gangzhou Wu and Yang Ruan and Shihua Chen and Ching Hua Lee and Zhenhua Ni},
journal= {arXiv preprint arXiv:2410.15763},
year = {2025}
}