4D Topological Insulators with Nodal-Line Boundary States

报告题目:4D Topological Insulators with Nodal-Line Boundary States

报告人:赵宇心  南京大学

报告时间:1211下午 16:00-17:00


报告邀请人: 江华

报告摘要:Conventional topological insulators and superconductors have topologically protected nodal points in their boundaries, and the recent interests in nodal-line semimetals merely concerned bulk band structures. In this talk, we present a novel four-dimensional topological insulator protected by an anti-unitary refection symmetry, whose boundary band has a single PT-symmetric nodal line with double topological charges. The construction of the model is guided by the K-theoretical formulation of the bulk-boundary correspondence of topological insulators. Fascinatingly, the Z2 bulk topological invariant is formulated as the second Chern number over a half Brilliance zone subtracted by Chern-Simons integrals over its boundaries, and therefore can be regarded as a four-dimensional generalization of the topological invariant of 2D time-reversal-invariant topological insulators. A cold-atom realization proposal will also be briefly discussed.

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