Observation of Anti-helical Edge States in Acoustic Metamaterials

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Hauptverfasser: Xia, Tianzhi, Zhang, Qicheng, Qiu, Chunyin
Format: Preprint
Veröffentlicht: 2025
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author Xia, Tianzhi
Zhang, Qicheng
Qiu, Chunyin
author_facet Xia, Tianzhi
Zhang, Qicheng
Qiu, Chunyin
contents As a hallmark of the quantum Hall effect, chiral edge modes (CEMs) counterpropagate along the two parallel edges of a ribbon structure. However, recent studies demonstrate counterintuitive antiCEMs that copropagate along the parallel edges. Analogous to the established extension of the CEMs to helical edge modes (HEMs) in the quantum spin Hall effect, it is natural to extend the antiCEMs to antiHEMs, which comprise a pair of time-reversal-related antiCEMs. In this Letter, we report the first observation of the antiHEMs based on a bilayer model that features staggered positive and negative interlayer hoppings. Experimentally, we implement this anti-helical model on an acoustic platform and provide compelling evidence for the antiHEMs by selectively exciting different spin subspaces, along with identifying the energybiased Dirac points in bulk spectra. Our findings may offer new insights into topological phases of matter and potentially pave the way for designing novel devices with unique edge transport properties.
format Preprint
id arxiv_https___arxiv_org_abs_2508_06825
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Observation of Anti-helical Edge States in Acoustic Metamaterials
Xia, Tianzhi
Zhang, Qicheng
Qiu, Chunyin
Mesoscale and Nanoscale Physics
Applied Physics
As a hallmark of the quantum Hall effect, chiral edge modes (CEMs) counterpropagate along the two parallel edges of a ribbon structure. However, recent studies demonstrate counterintuitive antiCEMs that copropagate along the parallel edges. Analogous to the established extension of the CEMs to helical edge modes (HEMs) in the quantum spin Hall effect, it is natural to extend the antiCEMs to antiHEMs, which comprise a pair of time-reversal-related antiCEMs. In this Letter, we report the first observation of the antiHEMs based on a bilayer model that features staggered positive and negative interlayer hoppings. Experimentally, we implement this anti-helical model on an acoustic platform and provide compelling evidence for the antiHEMs by selectively exciting different spin subspaces, along with identifying the energybiased Dirac points in bulk spectra. Our findings may offer new insights into topological phases of matter and potentially pave the way for designing novel devices with unique edge transport properties.
title Observation of Anti-helical Edge States in Acoustic Metamaterials
topic Mesoscale and Nanoscale Physics
Applied Physics
url https://arxiv.org/abs/2508.06825