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arXiv · 2307.12503

Spin-dependent gain and loss in photonic quantum spin Hall systems

Tian-Rui Liu·Kai Bai·Jia-Zheng Li·Liang Fang·Duanduan Wan·Meng Xiao
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Abstract

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.

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Tian-Rui Liu, Kai Bai, Jia-Zheng Li, Liang Fang, Duanduan Wan, Meng Xiao. 2023-07-24. Spin-dependent gain and loss in photonic quantum spin Hall systems. https://doi.org/10.1103/physrevb.108.l081101

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