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arXiv 1204.5682cond-mat.str-el
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分数拓扑绝缘体的薄环面极限

Thin-Torus Limit of Fractional Topological Insulators

B. Andrei Bernevig, N. Regnault

摘要:

我们解析和数值分析了分数拓扑绝缘体在一系列简单模型中的一维“薄环面”极限,这些模型表现出具有局部跳跃的完全平坦的带。这些模型是二维陈氏绝缘体的一维极限,投影到其最低能带的Hubbard型相互作用具有特别简单的形式。通过精确求解这些模型的多体相互作用谱,我们证明了与分数量子霍尔效应一样,薄环面极限的零模也是占据数满足广义泡利原理的CDW态.与薄环面CDW出现在轨道空间中的CDH相反,在薄环面FCI态中,CDW态在实空间中。我们发现,在能谱中的准空穴激发计数不能区分CDW态和CDH态。然而,通过精确计算薄环面态的纠缠谱,我们表明,它可以定性和定量区分CDW和分数拓扑状态,如FCI。然后,我们发现了一个以前未知的分离的能量尺度的完整的DIPH能谱薄环面极限,并发现陈省身绝缘体模型表现出强各向同性FCI状态有一个类似的结构,在他们的薄环面极限谱。我们关闭的能量和纠缠谱从薄环面的各向同性限制的数值计算的演变。我们的结果也可以解释为一个机构的分析,1维拓扑绝缘体稳定的反转对称性的存在下的相互作用。

英文摘要:

We analytically and numerically analyze the one-dimensional "thin-torus" limit of Fractional Topological Insulators in a series of simple models exhibiting exactly flat bands with local hopping. These models are the one-dimensional limit of two dimensional Chern Insulators, and the Hubbard-type interactions projected into their lowest band take particularly simple forms. By exactly solving the many-body interacting spectrum of these models, we show that, just like in the Fractional Quantum Hall effect, the zero modes of the thin-torus limit are CDW states of occupation numbers satisfying generalized Pauli principles. As opposed to the FQH where the thin-torus CDW appear in orbital space, in the thin-torus FCI states, the CDW states are in real-space. We show the counting of the quasihole excitations in the energy spectrum cannot distinguish between a CDW state and a FQH state. However, by exactly computing the entanglement spectrum for the thin-torus states, we show that it can qualitatively and quantitatively distinguish between a CDW and a fractional topological state such as the FCI. We then discover a previously unknown separation of energy scales of the full FQH energy spectrum in the thin torus limit and find that Chern insulator models exhibiting strong isotropic FCI states have a similar structure in their thin-torus limit spectrum. We close by numerically computing the evolution of energy and entanglement spectra from the thin-torus to the isotropic limit. Our results can also be interpreted as an analysis of one-body, 1-dimensional topological insulators stabilized by inversion symmetry in the presence of interactions.

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