各向异性四自旋XX链中的基态相图、高缠绕拓扑与Lifshitz临界性
Ground-State Phase Diagram, Higher-Winding Topology, and Lifshitz Criticality in an Anisotropic Four-Spin XX Chain
- University of Guilan（吉兰大学）
机构由 AI 辅助整理，请以论文原文为准。
AI总结：
本文研究横向磁场中带各向异性四自旋团簇相互作用的自旋-1/2 XX链的量子临界与拓扑性质，识别出Lifshitz型相变等，揭示高缠绕拓扑相的实现机制。
AI中文摘要：
我们研究了横向磁场中带有各向异性四自旋团簇相互作用的自旋-1/2 XX链的量子临界和拓扑性质。交换各向异性、团簇相互作用与外场的相互作用产生了包含多个有能隙拓扑相和不同量子临界边界的丰富相图。我们识别出由低能费米点结构重构产生的若干Lifshitz型相变，包括不同临界分支交汇且动量空间拓扑发生奇异重组的非常规多临界点。在各向同性极限下，通过费米点的合并与湮灭出现常规Lifshitz相变，揭示了同一模型内费米点重构的不同机制。有能隙相由量子化缠绕数ν=0、±1、-2和±3表征，高缠绕相由扩展团簇相互作用诱导。ν=±3相具有比常规短程Kitaev型链更丰富的拓扑结构，且通过场与相互作用驱动的能隙闭合与其他区域分离。这些拓扑差异进一步体现在体纠缠谱最低能级的特征简并模式中。我们的结果表明，各向异性多自旋相互作用为在一维量子系统中实现高缠绕拓扑相和非常规多临界性提供了通用途径。
英文摘要：
We investigate the quantum critical and topological properties of a spin-$1/2$ XX chain with anisotropic four-spin cluster interactions in a transverse magnetic field. The interplay of exchange anisotropy, cluster interactions, and the external field produces a rich phase diagram with multiple gapped topological phases and distinct quantum critical boundaries. We identify several Lifshitz-type transitions arising from reconstructions of the low-energy Fermi-point structure, including an unconventional multicritical point where distinct critical branches intersect and the momentum-space topology undergoes a singular reorganization. In the isotropic limit, a conventional Lifshitz transition emerges through the merging and annihilation of Fermi points, revealing distinct mechanisms of Fermi-point reconstruction within the same model. The gapped phases are characterized by quantized winding numbers $ν=0,\pm1,-2,$ and $\pm3$, with the higher-winding phases induced by the extended cluster interactions. The $ν=\pm3$ phases exhibit a richer topological structure than conventional short-range Kitaev-type chains and are separated from other sectors by field- and interaction-driven gap closings. These topological distinctions are further reflected in characteristic degeneracy patterns of the lowest levels of the bulk entanglement spectrum. Our results demonstrate that anisotropic multispin interactions provide a versatile route to realizing higher-winding topological phases and unconventional multicriticality in one-dimensional quantum systems.
