Observation of Degenerate Zero-Energy Topological States at Disclinations in an Acoustic Lattice

Yuanchen Deng, Wladimir A. Benalcazar, Ze Guo Chen, Mourad Oudich, Guancong Ma, Yun Jing

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36 Scopus citations


Building upon the bulk-boundary correspondence in topological phases of matter, disclinations have recently been harnessed to trap fractionally quantized density of states (DOS) in classical wave systems. While these fractional DOS have associated states localized to the disclination's core, such states are not protected from deconfinement due to the breaking of chiral symmetry, generally leading to resonances which, even in principle, have finite lifetimes and suboptimal confinement. Here, we devise and experimentally validate in acoustic lattices a paradigm by which topological states bind to disclinations without a fractional DOS but which preserve chiral symmetry. The preservation of chiral symmetry pins the states at the midgap, resulting in their protected maximal confinement. The integer DOS at the defect results in twofold degenerate states that, due to symmetry constraints, do not gap out. Our study provides a fresh perspective about the interplay between symmetry protection in topological phases and topological defects, with possible applications in classical and quantum systems alike.

Original languageEnglish (US)
Article number174301
JournalPhysical review letters
Issue number17
StatePublished - Apr 29 2022

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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