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  • Letter
  • Open Access

Experimental characterization of three-band braid relations in non-Hermitian acoustic lattices

Qicheng Zhang, Luekai Zhao, Xun Liu, Xiling Feng, Liwei Xiong, Wenquan Wu, and Chunyin Qiu*

  • Key Laboratory of Artificial Micro- and Nano-Structures of Ministry of Education and School of Physics and Technology Wuhan University, Wuhan 430072, China

  • *Corresponding author: cyqiu@whu.edu.cn
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Phys. Rev. Research 5, L022050 – Published 5 June, 2023

DOI: https://doi.org/10.1103/PhysRevResearch.5.L022050

Abstract

The nature of complex eigenenergy enables unique band topology in non-Hermitian (NH) lattices. Recently, there has been fast growing interest in the elusive winding and braiding topologies of the NH single and double bands, respectively. Here, we explore the even more intricate NH multiband topology and present an experimental characterization of the three-band braid relations by acoustic systems. Based on a concise tight-binding lattice model, we design a ternary cavity-tube structure equipped with a highly controllable unidirectional coupler, through which acoustic NH Bloch bands are experimentally reproduced in a synthetic space. We identify the NH braid relations from the global evolution of the eigenvalues and acoustic states, including a noncommutative braid relation σ1σ2≠σ2σ1 and a swappable braid relation σ1σ2σ1=σ2σ1σ2. Our results could promote the understanding of NH Bloch band topology and pave the way toward designing practical devices for manipulating acoustic states.

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Phys. Rev. Research 5, L022050– Published 5 June, 2023
  • Received 19 December 2022
  • Accepted 19 April 2023
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

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