Observation of topological phases without crystalline counterparts

Fuente: arXiv
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Main Authors: Yan, Mou, Tao, Yu-Liang, Hu, Yichong, Cui, Zhenxing, Wang, Jiong-Hao, Chen, Gang, Xu, Yong
Format: Preprint
Published: 2025
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_version_ 1866917099923832832
author Yan, Mou
Tao, Yu-Liang
Hu, Yichong
Cui, Zhenxing
Wang, Jiong-Hao
Chen, Gang
Xu, Yong
author_facet Yan, Mou
Tao, Yu-Liang
Hu, Yichong
Cui, Zhenxing
Wang, Jiong-Hao
Chen, Gang
Xu, Yong
contents Topological phases have been extensively studied primarily in crystalline systems with translational symmetry. Recent theoretical studies, however, have demonstrated the existence of topological phases in quasicrystals that are absent in crystals. Despite numerous experimental observations of topological phases in various crystalline systems, observing these phases without crystalline counterparts remains challenging due to very complex models. Here, we design a practically realizable tight-binding model with nearest-neighbor hopping on the Ammann-Beenker quasicrystalline lattice. This model respects eight-fold rotational and chiral symmetries, resulting in a higher-order topological phase with eight zero-energy corner modes that have no crystalline counterparts. We experimentally explore the topological phase in an acoustic quasicrystal. Surprisingly, we also discover symmetry-protected zero-energy modes near the center of the quasicrystal in a topologically trivial phase, a phenomenon not seen in crystals. We further experimentally observe these modes in a topologically trivial acoustic quasicrystal. Our work represents the first experimental observation of topological phases in quasicrystals without crystalline counterparts, paving the way for the study of exotic topological physics in quasicrystals.
format Preprint
id arxiv_https___arxiv_org_abs_2511_18357
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Observation of topological phases without crystalline counterparts
Yan, Mou
Tao, Yu-Liang
Hu, Yichong
Cui, Zhenxing
Wang, Jiong-Hao
Chen, Gang
Xu, Yong
Mesoscale and Nanoscale Physics
Topological phases have been extensively studied primarily in crystalline systems with translational symmetry. Recent theoretical studies, however, have demonstrated the existence of topological phases in quasicrystals that are absent in crystals. Despite numerous experimental observations of topological phases in various crystalline systems, observing these phases without crystalline counterparts remains challenging due to very complex models. Here, we design a practically realizable tight-binding model with nearest-neighbor hopping on the Ammann-Beenker quasicrystalline lattice. This model respects eight-fold rotational and chiral symmetries, resulting in a higher-order topological phase with eight zero-energy corner modes that have no crystalline counterparts. We experimentally explore the topological phase in an acoustic quasicrystal. Surprisingly, we also discover symmetry-protected zero-energy modes near the center of the quasicrystal in a topologically trivial phase, a phenomenon not seen in crystals. We further experimentally observe these modes in a topologically trivial acoustic quasicrystal. Our work represents the first experimental observation of topological phases in quasicrystals without crystalline counterparts, paving the way for the study of exotic topological physics in quasicrystals.
title Observation of topological phases without crystalline counterparts
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2511.18357