Experimental Observation of Non-Abelian Earring Nodal Links in Phononic Crystals

Mudi Wang, Shan Liu, Qiyun Ma, Ruo Yang Zhang, Dongyang Wang, Qinghua Guo, Biao Yang, Manzhu Ke, Zhengyou Liu, C. T. Chan

Research output: Contribution to journalArticlepeer-review

21 Scopus citations


Nodal lines are symmetry-protected one-dimensional band degeneracies in momentum space, which can appear in numerous topological configurations such as nodal rings, chains, links, and knots. Very recently, non-Abelian topological physics have been proposed in space-time inversion (PT) symmetric systems. One of the most special configurations in such systems is the earring nodal link, composing of a nodal chain linking with an isolated nodal line. Such earring nodal links have not been observed in real systems. We designed phononic crystals with earring nodal links, and experimentally observed two different kinds of earring nodal links by measuring the band structures. We found that the order of the nodal chain and line can be switched after band inversion but their link cannot be severed. Our Letter provides experimental evidence for phenomena unique to non-Abelian band topology and our acoustic system provides a convenient platform for studying the new materials carrying non-Abelian charges.
Original languageEnglish (US)
JournalPhysical Review Letters
Issue number24
StatePublished - Jun 14 2022
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy


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