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arXiv 2302.02798quant-phcond-mat.other
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由局域非厄米性诱导的无标度局域态的累积

Accumulation of scale-free localized states induced by local non-Hermiticity

Cui-Xian Guo, Xueliang Wang, Haiping Hu, Shu Chen

AI总结:

本研究针对局域非厄米性对厄米系统的影响问题,通过含PT对称局域非厄米项的双链模型精确解,发现非厄米性可诱导PT对称破缺、无标度局域态累积及迁移率边,增强非厄米性还可实现PT对称恢复,证明局域非厄米性能全局重塑厄米系统体性质。

摘要:

人们普遍认为,除了少数杂质诱导的束缚态之外,厄米系统的体态对局域厄米杂质或微扰不敏感。因此,探究局域非厄米性是否会对原始厄米系统造成剧烈改变具有重要意义。本文对此问题给出了肯定的回答,并针对具有宇称-时间($\boldsymbol{\textit{PT}}$)对称性、含局域非厄米项的双链模型,给出了精确解。在非厄米性的诱导下,系统会经历一系列$\boldsymbol{\textit{PT}}$对称破缺过程,破缺后本征能量以复共轭对的形式出现。与之对应的扩展体态会转变为无标度局域态,并在杂质周围发生单向累积。系统中存在迁移率边,将剩余的扩展态分隔开,直到所有本征态都实现完全无标度局域化。出人意料的是,进一步增强非厄米性会使系统进入$\boldsymbol{\textit{PT}}$对称恢复区域,此时除了一对复束缚态之外,能谱完全为实。我们证明,局域非厄米性诱导的无标度局域化是一种普遍现象,甚至可以在准周期无序条件下存在。我们的研究结果表明,原始厄米系统的体性质可以被局域非厄米性从全局上重塑。

英文摘要:

The bulk states of Hermitian systems are believed insensitive to local Hermitian impurities or perturbations except for a few impurity-induced bound states. Thus, it is important to ask whether \textit{local} non-Hermiticity can cause drastic changes to the original Hermitian systems. Here we address this issue affirmatively and present exact solutions for the double chain model with local non-Hermitian terms possessing parity-time ($\mathcal{PT}$) symmetry. Induced by the non-Hermiticity, the system undergoes a sequence of $\mathcal{PT}$-symmetry breakings, after which the eigenenergies appear in complex conjugate pairs. The associated extended bulk states then become scale-free localized and unidirectionally accumulated around the impurity. There exist mobility edges separating the residual extended states until a full scale-free localization of all eigenstates. Further increasing the non-Hermitity counter-intuitively brings the system to a $\mathcal{PT}$-restoration regime with fully real spectra except for a pair of complex bound states. We demonstrate that the local non-Hermiticity generated scale-free localization is a general phenomenon and can even survive the quasiperiodic disorder. Our results indicate that the bulk properties of the original Hermitian system can be globally reshaped by local non-Hermiticity.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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