Partial chiral symmetry-breaking as a route to spectrally isolated topological defect states in two-dimensional artificial materials
Partial chiral symmetry-breaking as a route to spectrally isolated topological defect states in two-dimensional artificial materials
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DOI：
10.1088/2053-1583/aa56de
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发表时间：
2017-06-01
期刊：
影响因子：
5.5
通讯作者：
Mortessagne, Fabrice
中科院分区：
文献类型：
--
作者：
Poli, Charles;Schomerus, Henning;Mortessagne, Fabrice
手性普适类的二部量子系统在点缺陷处承认拓扑保护零模。然而，在二维系统中，这些状态可能很难与扁平带产生的类似紧致的局部状态分开，如果两个亚晶格在一个单元胞内支持不同数量的位点，就会形成扁平带。在这里，我们确定了手性对称性的自然减少，这是由大多数子格上的偶联位点获得的，它产生了光谱隔离的点缺陷态，拓扑特征为由互补的少数子格支持的零模式。我们在具有次近邻耦合的二聚化Lieb晶格的微波实现中观察到这些状态，并通过亚晶格交错吸收证明了拓扑模式选择。
Bipartite quantum systems from the chiral universality classes admit topologically protected zero modes at point defects. However, in two-dimensional systems these states can be difficult to separate from compacton-like localized states that arise from flat bands, formed if the two sublattices support a different number of sites within a unit cell. Here we identify a natural reduction of chiral symmetry, obtained by coupling sites on the majority sublattice, which gives rise to spectrally isolated point-defect states, topologically characterized as zero modes supported by the complementary minority sublattice. We observe these states in a microwave realization of a dimerized Lieb lattice with next-nearest neighbour coupling, and also demonstrate topological mode selection via sublattice-staggered absorption.