半空间拓扑绝缘体迁移算子的Krein特征
Krein signatures of transfer operators for half-space topological insulators
摘要：
我们提出了一个补充的观点，拓扑不变量的二维紧束缚模型限制在半空间。这种系统的转移算子在无限维Krein空间$(\mathcal{K},J)$上是$J$ -幺正的，并且对于体带隙中的能量，在单位圆上只有离散谱。这些特征值具有Krein惯性，其可用于定义确定表面模式的性质的拓扑不变量，并允许区分不同的拓扑相位。数值结果说明了这一点。
英文摘要：
We propose a complementary point of view on the topological invariants of two-dimensional tight-binding models restricted to half-spaces. The transfer operators for such systems are $J$-unitary on a infinite dimensional Krein space $(\mathcal{K},J)$ and, for energies in the bulk gap, only have discrete spectrum on the unit circle. These eigenvalues have Krein inertia which can be used to define topological invariants determining the nature of the surface modes and allowing to distinguish different topological phases. This is illustrated by numerical results.
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