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arXiv 1801.08548cond-mat.str-el
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偶重态配对一维费米子模型中的非拓扑仿费米子

Non-topological parafermions in a one-dimensional fermionic model with even multiplet pairing

Leonardo Mazza, Fernando Iemini, Marcello Dalmonte, Christophe Mora

摘要:

本文讨论了一个一维费米子模型,该模型具有扩展Kitaev $\mathbb{Z}_{2}$链的广义$\mathbb{Z}_{N}$偶多重态配对.该系统与被认为具有局部边缘parafermions的模型有许多共同特征,最突出的是类似的玻色子化哈密顿量和$\mathbb{Z}_{N}$对称性,强制执行$N$折叠简并基态对某些无序具有鲁棒性。有趣的是,我们表明,该系统支持一对parafermions,但他们是非本地的,而不是边界运营商。结果表明,基态的简并只是部分拓扑的,并与(两粒子)配对场引起的自发对称性破缺共存。每个破环扇区具有一对编码拓扑二重简并的Majorana边模。由两个带绝缘体包围,该模型表现出$N=4$的双重的$8 π$分数约瑟夫森效应突出的存在下的parafermion。

英文摘要:

We discuss a one-dimensional fermionic model with a generalized $\mathbb{Z}_{N}$ even multiplet pairing extending Kitaev $\mathbb{Z}_{2}$ chain. The system shares many features with models believed to host localized edge parafermions, the most prominent being a similar bosonized Hamiltonian and a $\mathbb{Z}_{N}$ symmetry enforcing an $N$-fold degenerate ground state robust to certain disorder. Interestingly, we show that the system supports a pair of parafermions but they are non-local instead of being boundary operators. As a result, the degeneracy of the ground state is only partly topological and coexists with spontaneous symmetry breaking by a (two-particle) pairing field. Each symmetry-breaking sector is shown to possess a pair of Majorana edge modes encoding the topological twofold degeneracy. Surrounded by two band insulators, the model exhibits for $N=4$ the dual of an $8 π$ fractional Josephson effect highlighting the presence of parafermions.

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