Hidden multi-topological phases mediated by constrained inter-cell coupling

Ziteng Wang; Domenico Bongiovanni; Xiangdong Wang; Zhichan Hu; Dario Jukić; Daohong Song; Jingjun Xu; Roberto Morandotti; Zhigang Chen; Hrvoje Buljan

doi:10.1186/s43593-025-00118-5

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Hidden multi-topological phases mediated by constrained inter-cell coupling

eLight Vol. 6, (2026)

Research Article | Updated：2026-03-16

- Hidden multi-topological phases mediated by constrained inter-cell coupling
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- DOI：10.1186/s43593-025-00118-5
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- Received：11 July 2025，
  
  Revised：2025-10-30，
  
  Accepted：12 November 2025，
  
  Online First：13 January 2026，
  
  Published：2026-12
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Ziteng Wang, Domenico Bongiovanni, Xiangdong Wang, et al. Hidden multi-topological phases mediated by constrained inter-cell coupling[J]. eLight, 2026, 6.
DOI：

Ziteng Wang, Domenico Bongiovanni, Xiangdong Wang, et al. Hidden multi-topological phases mediated by constrained inter-cell coupling[J]. eLight, 2026, 6. DOI： 10.1186/s43593-025-00118-5.

摘要

Abstract

The discovery of topological phases of matter and topological boundary states had a tremendous impact on condensed matter physics

photonics

and material sciences

where topological phases are defined via energy bands

described by the topological band theory. However

there are topological materials that cannot be described by this theory

which support non-trivial boundary states but are little-known and largely unexplored. Here

we uncover a new class of topological phases—termed "multi-topological phase" (MTPs)—arising from constrained inter-cell coupling in lattice systems

and experimentally demonstrate them in a photonic platform. The MTP features multiple sets of boundary states

where each set is associated with one distinct topological invariant. Unlike conventional topological phases

the MTP cannot be identified via the original band structure

being a "hidden" topological phase

where the phase transition can occur without band-gap closing. We present typical examples of MTPs in both one- and two-dimensional structures

as well as in indirectly gapped Chern insulators

beyond the regime where the conventional bulk-boundary correspondence predicts the existence of boundary states. Furthermore

we directly observe the MTPs in the first two examples using laser-written photonic lattices. Our work offers a new design strategy for topological materials

paving the way for future exploration and applications in photonics.

关键词

Keywords

references

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