Observation of D-class topology in an acoustic metamaterial

Shi Qiao Wu, Wenting Cheng, Xiao Yu Liu, Bing Quan Wu, Emil Prodan, Camelia Prodan, Jian Hua Jiang

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Topological materials and metamaterials opened new paradigms to create and manipulate phases of matter with unconventional properties. Topological D-class phases (TDPs) are archetypes of the ten-fold classification of topological phases with particle-hole symmetry. In two dimensions, TDPs support propagating topological edge modes that simulate the elusive Majorana elementary particles. Furthermore, a piercing of π-flux Dirac-solenoids in TDPs stabilizes localized Majorana excitations that can be braided for the purpose of topological quantum computation. Such two-dimensional (2D) TDPs have been a focus in the research frontier, but their experimental realizations are still under debate. Here, with a novel design scheme, we realize 2D TDPs in an acoustic crystal by synthesizing both the particle-hole and fermion-like time reversal symmetries for a wide range of frequencies. The design scheme leverages an enriched unit cell structure with real-valued couplings that emulate the targeted Hamiltonian of TDPs with complex hoppings: A technique that could unlock the realization of all topological classes with passive metamaterials. In our experiments, we realize a pair of TDPs with opposite Chern numbers in two independent sectors that are connected by an intrinsic fermion-like time-reversal symmetry built in the system. We measure the acoustic Majorana-like helical edge modes and visualize their robust topological transport, thus revealing the unprecedented D and DIII class topologies with direct evidence. Our study opens up a new pathway for the experimental realization of two fundamental classes of topological phases and may offer new insights in fundamental physics, materials science, and phononic information processing.

Original languageEnglish (US)
JournalScience Bulletin
DOIs
StateAccepted/In press - 2024

All Science Journal Classification (ASJC) codes

  • General

Keywords

  • Chiral symmetry
  • D-class topology
  • Gapless edge states
  • Particle-hole symmetry
  • Time-reversal symmetry

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