标题： 二维+一维系统中的拓扑缺陷来自三维+一维块体中的线激发 显示英文标题

标题： Topological defects of 2+1D systems from line excitations in 3+1D bulk

摘要： 拓扑相的体-边界对应关系表明 d+1 维体中的拓扑特征与 (d-1)+1 维边界上可能无能隙的理论之间存在强关联性。 在 2+1D 拓扑相中，体内的任意子激发可以直接对应于边界 1+1D 共形场论中的拓扑点缺陷/主场。 本文中，我们利用拓扑全息/对称性拓扑场论框架研究了 3+1D 拓扑相中的线激发如何成为边界 2+1D 理论中的线缺陷。我们强调“派生”线激发的重要性，并特别展示了马约拉纳链缺陷的效果：它导致了 3+1D 费米子 Z2 拓扑序的一个独特凝聚环隙边界态，并在描述两种类型凝聚环边界之间的过渡的 2+1D 马约拉纳锥临界理论中留下印记。 非可逆线激发（如柴郡弦）在玻色子 3+1D 拓扑相及其对应的 2+1D 临界点中的影响也被讨论。 显示英文摘要

摘要： The bulk-boundary correspondence of topological phases suggests strong connections between the topological features in a d+1-dimensional bulk and the potentially gapless theory on the (d-1)+1-dimensional boundary. In 2+1D topological phases, a direct correspondence can exist between anyonic excitations in the bulk and the topological point defects/primary fields in the boundary 1+1D conformal field theory. In this paper, we study how line excitations in 3+1D topological phases become line defects in the boundary 2+1D theory using the Topological Holography/Symmetry Topological Field Theory framework. We emphasize the importance of "descendent" line excitations and demonstrate in particular the effect of the Majorana chain defect: it leads to a distinct loop condensed gapped boundary state of the 3+1D fermionic Z2 topological order, and leaves signatures in the 2+1D Majorana-cone critical theory that describes the transition between the two types of loop condensed boundaries. Effects of non-invertible line excitations, such as Cheshire strings, are also discussed in bosonic 3+1D topological phases and the corresponding 2+1D critical points.