Observing half-integer topological winding numbers in non-Hermitian synthetic lattices

Mu Yang; Yu-Wei Liao; Hao-Qing Zhang; Yue Li; Zhi-He Hao; Zheng-Wei Zhou; Xi-Wang Luo; Jin-Shi Xu; Chuan-Feng Li; Guang-Can Guo

doi:10.1038/s41377-025-01909-8

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Observing half-integer topological winding numbers in non-Hermitian synthetic lattices

Original Articles

- Observing half-integer topological winding numbers in non-Hermitian synthetic lattices
- Light: Science & Applications Vol. 14, Issue 8, Pages: 2308-2316(2025)
- Affiliations：
  
  1.Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
  2.Anhui Province Key Laboratory of Quantum Network, University of Science and Technology of China, Hefei, Anhui 230026, China
  3.CAS Center For Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
  4.Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
- Author bio：
  
  Xi-Wang Luo (luoxw@ustc.edu.cn)
  Jin-Shi Xu (jsxu@ustc.edu.cn)
  Chuan-Feng Li (cfli@ustc.edu.cn)
- Funds：
- DOI：10.1038/s41377-025-01909-8
  CLC：
- Received：29 December 2024，
  
  Revised：05 May 2025，
  
  Accepted：23 May 2025，
  
  Published Online：24 June 2025，
  
  Published：31 August 2025
- Accepted：
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Yang, M. et al. Observing half-integer topological winding numbers in non-Hermitian synthetic lattices. Light: Science & Applications, 14, 2308-2316 (2025).
DOI：

Yang, M. et al. Observing half-integer topological winding numbers in non-Hermitian synthetic lattices. Light: Science & Applications, 14, 2308-2316 (2025). DOI： 10.1038/s41377-025-01909-8.

摘要

Abstract

Non-Hermitian (NH) systems have revealed unique topological phenomena that are not observed in Hermitian counterparts

such as novel topology classifications and the NH skin effect. In periodic NH systems

eigenenergies become complex and exhibit windings in the complex plane

while eigenstate winding numbers

which are strictly integers in Hermitian systems

can take half-integer values. However

direct experimental observation of NH winding of both eigenenergies and eigenstates

especially the half-integer winding

remains a significant challenge. In this work

we utilize the orbital angular momentum (OAM) synthetic dimension to construct an NH topological lattice and achieve direct observation of both eigenstate and eigenenergy windings. We report the first experimental observation of a half-integer eigenstate winding number

and reveal the intrinsic relationship between the direction in the NH skin dynamics and eigenenergy windings. Furthermore

by partitioning the OAM chain into two semi-infinite chains

we observe zero boundary modes and demonstrate that their distributions are jointly determined by the winding numbers of both the eigenstates and eigenenergies. This work provides comprehensive insights into NH topologies and offers a new experimental platform for exploring NH phenomena.

关键词

Keywords

references

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