Antichiral hinge states in a higher-order photonic nodal ring semimetal

Yuchen Peng; Deep Mondal; Yuting Yang; Wanting Wu; Bo Zhao; Shuaiyang Wei; Zhenzhi Liu; Wenrong Qi; Xiaokang Dai; Minqi Cheng; Weili Li; Xinyi Zhang; Fei-Fei Li; Rimi Banerjee; Minggui Wei; Jingyi Tian; Peiheng Zhou; Subhaskar Mandal; Baile Zhang; Gui-Geng Liu

arXiv · 2607.25688

Antichiral hinge states in a higher-order photonic nodal ring semimetal

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Abstract

Antichiral states propagate in the same direction on opposite boundaries, defying the conventional constraint that boundary modes must cancel net chirality. Previously found antichiral states have been limited to first-order topological semimetals. However, antichiral hinge states, the antichiral counterpart of recently discovered higher-order chiral hinge states, remain elusive. Here, we report the observation of antichiral hinge states in a higher-order nodal-ring semimetal made of a three-dimensional gyromagnetic photonic crystal. Near-field scanning measurements reveal a pair of hinge states at two parallel one-dimensional boundaries propagating unidirectionally along the same direction, with robust transport against metallic scatterers. Their spatial positions can be reconfigured by adding or removing photonic layers. The additionally observed antichiral and drumhead surface states manifest a hierarchy of first- and second-order topological boundary states within a single photonic system. Our work extends antichiral states to higher-order topological semimetals and has potential applications in robust and reconfigurable photonic routing.

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Yuchen Peng, Deep Mondal, Yuting Yang, Wanting Wu, Bo Zhao, Shuaiyang Wei, Zhenzhi Liu, Wenrong Qi, Xiaokang Dai, Minqi Cheng, Weili Li, Xinyi Zhang, Fei-Fei Li, Rimi Banerjee, Minggui Wei, Jingyi Tian, Peiheng Zhou, Subhaskar Mandal, Baile Zhang, Gui-Geng Liu. 2026-07-28. Antichiral hinge states in a higher-order photonic nodal ring semimetal. https://arxiv.org/abs/2607.25688

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