Topological phases are greatly enriched by including non-Hermiticity. While most works focus on the topology of the eigenvalues and eigenstates, how topologically nontrivial non-Hermitian systems behave in dynamics has only drawn limited attention. Here, we consider a breathing honeycomb lattice known to emulate the quantum spin Hall effect and exhibits higher-order corner modes. We find that non-reciprocal intracell couplings introduce gain in one pseudo-spin subspace while loss with the same magnitude in the other. In addition, non-reciprocal intracell couplings can also suppress the spin mixture of the edge modes at the boundaries and delocalize the higher-order corner mode. Our findings deepen the understanding of non-Hermitian topological phases and bring in the spin degree of freedom in manipulating the dynamics in non-Hermitian systems.
@article{arxiv.2307.12503,
title = {Spin-dependent gain and loss in photonic quantum spin Hall systems},
author = {Tian-Rui Liu and Kai Bai and Jia-Zheng Li and Liang Fang and Duanduan Wan and Meng Xiao},
journal= {arXiv preprint arXiv:2307.12503},
year = {2023}
}