论文标题

奇数空间维度的本地拓扑标记及其在无定形拓扑问题上的应用

Local Topological Markers in Odd Spatial Dimensions and Their Application to Amorphous Topological Matter

论文作者

Hannukainen, Julia D., Martinez, Miguel F., Bardarson, Jens H., Kvorning, Thomas Klein

论文摘要

本地拓扑标记,通过局部预期值评估的拓扑不变性,对于表征缺乏翻译不变性的材料的拓扑阶段而言是有价值的。 Chern标记 - 以傅立叶变换的Chern角色表示的Chern数字是在均匀尺寸上易于适用的本地标记,但是对于奇数尺寸没有类似的表达式。 We provide general analytic expressions for local markers for free-fermion topological states in odd dimensions protected by local symmetries: a Chiral marker, a local $\mathbb Z$ marker which in case of translation invariance is equivalent to the chiral winding number, and a Chern-Simons marker, a local $\mathbb Z_2$ marker characterizing all nonchiral phases in odd dimensions.我们通过引入单粒子密度矩阵的单粒子密度矩阵插值和感兴趣状态之间的单颗粒密度矩阵的单个参数$ p _ {\ vartheta} $来实现这一目标。通过将参数$ \ vartheta $解释为附加维度,我们计算了家族$ p _ {\ vartheta} $的Chern标记。我们通过在三个维度上表征两个无定形哈密顿量的拓扑阶段来证明这些标记的实际使用:拓扑超导体($ \ MATHBB Z $分类)和拓扑绝缘器($ \ MathBB Z_2 $分类)。

Local topological markers, topological invariants evaluated by local expectation values, are valuable for characterizing topological phases in materials lacking translation invariance. The Chern marker -- the Chern number expressed in terms of the Fourier transformed Chern character -- is an easily applicable local marker in even dimensions, but there are no analogous expressions for odd dimensions. We provide general analytic expressions for local markers for free-fermion topological states in odd dimensions protected by local symmetries: a Chiral marker, a local $\mathbb Z$ marker which in case of translation invariance is equivalent to the chiral winding number, and a Chern-Simons marker, a local $\mathbb Z_2$ marker characterizing all nonchiral phases in odd dimensions. We achieve this by introducing a one-parameter family $P_{\vartheta}$ of single-particle density matrices interpolating between a trivial state and the state of interest. By interpreting the parameter $\vartheta$ as an additional dimension, we calculate the Chern marker for the family $P_{\vartheta}$. We demonstrate the practical use of these markers by characterizing the topological phases of two amorphous Hamiltonians in three dimensions: a topological superconductor ($\mathbb Z$ classification) and a topological insulator ($\mathbb Z_2$ classification).

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