Braiding topology of symmetry-protected degeneracy points in non-Hermitian systems

• URL: http://arxiv.org/abs/2309.16152v2
• Date: Mon, 8 Jan 2024 02:41:08 GMT
• Title: Braiding topology of symmetry-protected degeneracy points in non-Hermitian systems
• Authors: Jia-Zheng Li, Kai Bai, Cheng Guo, Tian-Rui Liu, Liang Fang, Duanduan Wan, Meng Xiao
• Abstract summary: We find that pairwise-created symmetry-protected degeneracy points merge into a higher-order degeneracy point, which goes beyond the abelian picture. Our findings empower researchers across diverse fields to uncover new phenomena and applications harnessing symmetry-protected non-Hermitian degeneracy points.
• Score: 6.900105712241852
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Degeneracy points in non-Hermitian systems are of great interest. While a homotopic framework exists for understanding their behavior in the absence of symmetry, it does not apply to symmetry-protected degeneracy points with reduced codimension. In this work, utilizing algebraic topology, we provide a systematic classification of these symmetry-protected degenerate points and investigate the braid conservation rule followed by them. Using a model Hamiltonian and circuit simulation, we discover that, contrary to simple annihilation, pairwise-created symmetry-protected degeneracy points merge into a higher-order degeneracy point, which goes beyond the abelian picture. Our findings empower researchers across diverse fields to uncover new phenomena and applications harnessing symmetry-protected non-Hermitian degeneracy points.

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