用纠缠见证探测杂质量子临界性
Probing Impurity Quantum Criticality with Entanglement Witnesses
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中文总结 AI 辅助
本文以双杂质近藤模型为研究对象，利用密度矩阵与数值重整化群计算，证明可测量自旋电荷涨落可作为量子临界性的纠缠见证，确立了杂质系统探测量子临界纠缠的可控场景。
中文摘要 AI 辅助
纠缠是量子力学的核心特征，其与量子临界性的关联是当前研究热点。本文针对双杂质近藤模型（该模型可通过耦合量子点及表面添加磁性杂质实现实验验证），证明可测量的自旋与电荷涨落能作为量子临界性的纠缠见证。我们采用密度矩阵重整化群（DMRG）与数值重整化群（NRG）计算，确定了将两个独立近藤屏蔽杂质与杂质间单态分隔开的非费米液体临界点，并将其解释为每个局域矩的主导纠缠伙伴发生变化：从局域矩与扩展传导电子自由度集的纠缠，转变为与另一杂质的纠缠。这种重组伴随杂质-浴纠缠与杂质间磁化率的奇异响应。我们还展示了该结构如何编码于零温及有限温下集体自旋与电荷算符的量子费舍尔信息中，将纠缠图像与可实验测量的动力学响应函数关联起来。研究结果确立了杂质系统作为可控场景，可通过可测量关联探测量子临界纠缠，为从纠缠角度理解重费米子物理提供了进一步见解。
英文摘要
Entanglement is a defining feature of quantum mechanics, and its relation to quantum criticality is of considerable current interest. Here we show that measurable spin and charge fluctuations provide an entanglement witness of quantum criticality in the two-impurity Kondo model, which has experimental realizations in terms of coupled quantum dots and magnetic impurities added to surfaces. We use density-matrix renormalization group and numerical renormalization group calculations to resolve the non-Fermi-liquid critical point separating two independently Kondo-screened impurities from an inter-impurity singlet and interpret it as a change in the dominant entanglement partner of each local moment: from entanglement of the local moment with an extended set of conduction-electron degrees of freedom to entanglement with the other impurity. This reorganization is accompanied by a singular response of the impurity-bath entanglement and the inter-impurity susceptibility. We show how the same structure is encoded in the quantum Fisher information of collective spin and charge operators at zero and finite temperatures, connecting the entanglement picture to experimentally accessible dynamical response functions. Our results establish impurity systems as controlled settings in which quantum-critical entanglement can be detected through measurable correlations, and provide further insight into the possibility of understanding heavy-fermion physics in terms of entanglement.
