中国物理B ›› 2025, Vol. 34 ›› Issue (11): 110303-110303.doi: 10.1088/1674-1056/addcbe

• • 上一篇    下一篇

Exceptional rings and non-Abelian topology in non-Hermitian high-spin systems

Peng-Zhen Sun(孙鹏震), Zhou-Tao Lei(雷周涛), and Yuan-Gang Deng(邓元刚)   

  1. Guangdong Provincial Key Laboratory of Quantum Metrology and Sensing & School of Physics and Astronomy, Sun Yat-Sen University (Zhuhai Campus), Zhuhai 519082, China
  • 收稿日期:2025-03-19 修回日期:2025-05-21 接受日期:2025-05-23 发布日期:2025-11-13
  • 通讯作者: Yuan-Gang Deng E-mail:dengyg3@mail.sysu.edu.cn
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 12274473 and 12135018).

Exceptional rings and non-Abelian topology in non-Hermitian high-spin systems

Peng-Zhen Sun(孙鹏震), Zhou-Tao Lei(雷周涛), and Yuan-Gang Deng(邓元刚)   

  1. Guangdong Provincial Key Laboratory of Quantum Metrology and Sensing & School of Physics and Astronomy, Sun Yat-Sen University (Zhuhai Campus), Zhuhai 519082, China
  • Received:2025-03-19 Revised:2025-05-21 Accepted:2025-05-23 Published:2025-11-13
  • Contact: Yuan-Gang Deng E-mail:dengyg3@mail.sysu.edu.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 12274473 and 12135018).

摘要: Topological phases featuring non-Abelian charges have garnered significant attention in recent years. In parallel, the study of multiband exceptional topology in non-Hermitian systems has emerged as a prominent research direction. In this study, we investigate a parity-time (PT) symmetric Hamiltonian, which hosts both conventional non-Abelian topological phases (NATPs) and hybrid phases. We propose an experimental scheme using spin-1 atoms with spin-orbit coupling trapped in two-dimensional (2D) lattices. Before adding a non-Hermitian term, we find the emergence of distinct topological phases mixed by two NATPs and establish their connection with NATPs theory. When a non-Hermitian term that preserves PT symmetry protection was introduced, stable second-order exceptional rings and third-order exceptional points emerge and they drive the edge states to manifest as discontinuous Fermi arcs in the surface Brillouin zone. However, with the variation of the non-Hermitian term, it is rather intriguing that two types of exceptional rings here transition from being internally tangent to externally tangent, transforming into a new topological phase equivalent to the Hermitian case. This research provides deeper insights into the nature of NATPs and the topological implications of exceptional structures, contributing to the field of topological physics.

关键词: non-Abelian topology, parity-time symmetry, exceptional point, ultracold atoms

Abstract: Topological phases featuring non-Abelian charges have garnered significant attention in recent years. In parallel, the study of multiband exceptional topology in non-Hermitian systems has emerged as a prominent research direction. In this study, we investigate a parity-time (PT) symmetric Hamiltonian, which hosts both conventional non-Abelian topological phases (NATPs) and hybrid phases. We propose an experimental scheme using spin-1 atoms with spin-orbit coupling trapped in two-dimensional (2D) lattices. Before adding a non-Hermitian term, we find the emergence of distinct topological phases mixed by two NATPs and establish their connection with NATPs theory. When a non-Hermitian term that preserves PT symmetry protection was introduced, stable second-order exceptional rings and third-order exceptional points emerge and they drive the edge states to manifest as discontinuous Fermi arcs in the surface Brillouin zone. However, with the variation of the non-Hermitian term, it is rather intriguing that two types of exceptional rings here transition from being internally tangent to externally tangent, transforming into a new topological phase equivalent to the Hermitian case. This research provides deeper insights into the nature of NATPs and the topological implications of exceptional structures, contributing to the field of topological physics.

Key words: non-Abelian topology, parity-time symmetry, exceptional point, ultracold atoms

中图分类号:  (Phases: geometric; dynamic or topological)

  • 03.65.Vf
11.30.Er (Charge conjugation, parity, time reversal, and other discrete symmetries) 42.50.-p (Quantum optics) 67.85.-d (Ultracold gases, trapped gases)