College of Optics & Photonics-CREOL, University of Central Florida, Orlando, FL, USA.
Department of Electrical and Computer Engineering, Aristotle University of Thessaloniki, Thessaloniki, Greece.
Nat Mater. 2022 Jun;21(6):634-639. doi: 10.1038/s41563-022-01238-w. Epub 2022 Apr 28.
Topological theories have established a unique set of rules that govern the transport properties in a wide variety of wave-mechanical settings. In a marked departure from the established approaches that induce Floquet topological phases by specifically tailored discrete coupling protocols or helical lattice motions, we introduce a class of bimorphic Floquet topological insulators that leverage connective chains with periodically modulated on-site potentials to reveal rich topological features in the system. In exploring a 'chain-driven' generalization of the archetypical Floquet honeycomb lattice, we identify a rich phase structure that can host multiple non-trivial topological phases associated simultaneously with both Chern-type and anomalous chiral states. Experiments carried out in photonic waveguide lattices reveal a strongly confined helical edge state that, owing to its origin in bulk flat bands, can be set into motion in a topologically protected fashion, or halted at will, without compromising its adherence to individual lattice sites.
拓扑理论建立了一套独特的规则，这些规则支配着广泛的波动力学环境中的输运性质。与通过专门设计的离散耦合协议或螺旋晶格运动来诱导 Floquet 拓扑相的已有方法明显不同，我们引入了一类双形态 Floquet 拓扑绝缘体，利用具有周期性调制局域势的连接链来揭示系统中的丰富拓扑特征。在探索典型的 Floquet 蜂窝晶格的“链驱动”推广时，我们确定了一个丰富的相结构，该结构可以同时容纳多个非平凡的拓扑相，这些拓扑相与 Chern 型和反常手性态都有关联。在光子波导晶格中进行的实验揭示了一种强烈受限的螺旋边缘态，由于其起源于体带中的平坦带，因此可以以拓扑保护的方式运动，或者可以根据需要停止，而不会违反其对单个晶格位置的遵守。
