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arXiv 2502.04559cond-mat.str-elcond-mat.mes-hallcond-mat.quant-gasquant-ph
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广义η-配对方法用于任意维度的相互作用非厄密系统

Generalized $η$-pairing approach to interacting non-Hermitian systems in arbitrary dimensions

School of Physics, Zhengzhou University(郑州大学物理学院)

Kai Lieta

AI总结:

本文提出广义eta-配对方法,揭示了非厄密Hubbard模型中多种新现象,包括非厄密角动量算符和异常局域化,以及在任意维度下的理论框架。

摘要:

我们推广了eta-配对理论,应用于非常一般的非厄密Hubbard模型,并发现了许多没有厄密对应物的新现象。例如,eta-配对本征算符的厄密共轭可能不是本征算符,eta-配对本征算符可以被空间调制,且即使H与eta-配对算符对易,SU(2)伪自旋对称性也可能不成立。值得注意的是,这些新颖的非厄密现象通过我们建立的几条定理紧密相关,可以导致例如新的类型的eta-配对算符(如非厄密角动量算符)和eta-配对本征态的异常局域化。一些关于SO(4)和粒子-空穴对称性的疑问得到澄清。我们的通用eta-配对理论还揭示了Hubbard模型这些对称性的 previously unnoticed unification。为了举例这些发现,我们首先提出了一维Hatano-Nelson-Hubbard模型(有或无体积分量不变性),并显示右和左两个粒子eta-配对本征态在链的两端呈指数局域化。然后,我们将此模型推广到二维,发现eta-配对本征态可以表现出一阶或二阶皮肤效应。最后,为了实现所有非厄密eta-配对现象,我们构建了一个定义在任意晶格上的通用双子晶格模型;该模型也可以揭示具有厄密跃迁的系统中的eta-配对结构,包括原始的eta-配对理论用于正方形晶格、扩展到三角晶格以及一些拓扑系统。我们的结果建立了一个新的、严谨的理论框架,用于研究相互作用非厄密多体系统中的新量子现象,即使在任意空间维度和没有体积分量对称性的情况下。

英文摘要:

Developing a general and rigorous analytical approach to non-Hermitian many-body systems is a challenging task. Here, we generalize the eta-pairing theory to very general non-Hermitian Hubbard models and find many novel phenomena without Hermitian analogs. For instance, the Hermitian conjugate of an eta-pairing eigenoperator may not be an eigenoperator, eta-pairing eigenoperators can be spatially modulated, and the $SU(2)$ pseudospin symmetry may not be possible even if $H$ commutes with the eta-pairing operators. Remarkably, these novel non-Hermitian phenomena are closely related to each other by several theorems we establish and can lead to, for example, new types of eta-pairing operators (e.g., the notion of non-Hermitian angular-momentum operators) and the Fock space localization of many-body eta-pairing eigenstates. Some issues on the $SO(4)$ and particle-hole symmetries are clarified. Our general eta-pairing theory also reveals a previously unnoticed unification of these symmetries of the Hubbard model. These general results can be illustrated with concrete examples such as the generalized Hatano-Nelson-Hubbard models and a general two-sublattice model. In particular, the general two-sublattice model can reveal the eta-pairing structure [e.g., the $SO(4)$ symmetry] in systems with Hermitian hoppings, including the original eta-pairing theory for square lattice, the extension to triangular lattice, and some topological systems. Our results establish a new and rigorous theoretical framework for studying interacting non-Hermitian systems in arbitrary spatial dimensions, even without bulk translation symmetry.

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