非厄米系统中杨-李边奇点的动力学特征
Dynamical signatures of the Yang-Lee edge singularity in non-Hermitian systems
AI总结：
该研究针对杨-李边奇点在相互作用多体系统中难以实验实现的问题，提出利用非厄米系统的非幺正动力学，通过两类洛施密特回波观测该奇点，在两类模型中识别例外点并测定符合理论的临界指数，提供了直接观测的新途径。
摘要：
杨-李边奇点是一种以非幺正场论为特征的奇特临界现象，然而其在相互作用多体系统中的实验实现仍难以实现。我们研究表明，被视为多体例外点的杨-李边奇点，可利用非厄米系统的非幺正动力学优势，通过自归一化及关联双正交洛施密特回波进行观测。研究证实，洛施密特回波在$\boldsymbol{\text{PT}}$对称区表现出幺正动力学，在$\boldsymbol{\text{PT}}$对称破缺区则表现出非幺正动力学，从而在例外点附近产生急剧变化。我们据此在非厄米横场Ising模型和Yang-Lee模型中识别出例外点，并测定了与非幺正共形场论一致的临界指数。该工作为直接观测非厄米多体系统中由非幺正动力学产生的杨-李边奇点提供了途径。
英文摘要：
The Yang-Lee edge singularity is an intriguing critical phenomenon characterized by nonunitary field theory. However, its experimental realization for interacting many-body systems remains elusive. We show that Yang-Lee edge singularities, regarded as many-body exceptional points, can be observed using both the self-normal and the associated-biorthogonal Loschmidt echoes, leveraging the advantages of nonunitary dynamics in non-Hermitian systems. The Loschmidt echoes are demonstrated to display unitary dynamics in the $\mathcal{PT}$-symmetric regime but exhibit nonunitary dynamics in the $\mathcal{PT}$ symmetry-broken regime, leading to a sharp change near an exceptional point. We hereby identify exceptional points in both the non-Hermitian transverse field Ising model and the Yang-Lee model, and determine the critical exponent that is consistent with nonunitary conformal field theory. This work provides a direct observation of Yang-Lee edge singularities in non-Hermitian many-body systems arising from nonunitary dynamics.
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