Topological Chern vectors in three-dimensional photonic crystals

Liu，Gui Geng1; Gao，Zhen2; Wang，Qiang1; Xi，Xiang2; Hu，Yuan Hang3; Wang，Maoren3; Liu，Chengqi3; Lin，Xiao4; Deng，Longjiang3; Yang，Shengyuan A.5; Zhou，Peiheng3; Yang，Yihao4; Chong，Yidong1,6; Zhang，Baile1,6

2022-09-29

10.1038/s41586-022-05077-2

NATURE   Impact Factor & Quartile

0028-0836

1476-4687

The paradigmatic example of a topological phase of matter, the two-dimensional Chern insulator, is characterized by a topological invariant consisting of a single integer, the scalar Chern number. Extending the Chern insulator phase from two to three dimensions requires generalization of the Chern number to a three-vector, similar to the three-dimensional (3D) quantum Hall effect. Such Chern vectors for 3D Chern insulators have never been explored experimentally. Here we use magnetically tunable 3D photonic crystals to achieve the experimental demonstration of Chern vectors and their topological surface states. We demonstrate Chern vector magnitudes of up to six, higher than all scalar Chern numbers previously realized in topological materials. The isofrequency contours formed by the topological surface states in the surface Brillouin zone form torus knots or links, whose characteristic integers are determined by the Chern vectors. We demonstrate a sample with surface states forming a (2, 2) torus link or Hopf link in the surface Brillouin zone, which is topologically distinct from the surface states of other 3D topological phases. These results establish the Chern vector as an intrinsic bulk topological invariant in 3D topological materials, with surface states possessing unique topological characteristics.

SCI

English

NI Journal Papers

Others

Singapore National Research Foundation Competitive Research Program[NRF-CRP23-2019-0007] ; Singapore Ministry of Education Academic Research Fund Tier3[MOE2016-T3-1-006] ; National Natural Science Foundation of China["52022018","52021001","12104211","6101020101","62175215"] ; Chinese Academy of Engineering[2022-XY-127]

Science & Technology - Other Topics

Multidisciplinary Sciences

WOS:000862041000026

NATURE PORTFOLIO

BIOLOGY & BIOCHEMISTRY;CLINICAL MEDICINE;MULTIDISCIPLINARY;PLANT & ANIMAL SCIENCE;ENVIRONMENT/ECOLOGY;SOCIAL SCIENCES, GENERAL;MICROBIOLOGY;ECONOMICS BUSINESS;IMMUNOLOGY;MATERIALS SCIENCE;COMPUTER SCIENCE;SPACE SCIENCE;MOLECULAR BIOLOGY & GENETICS;CHEMISTRY;NEUROSCIENCE & BEHAVIOR;PHYSICS;GEOSCIENCES;ENGINEERING

2-s2.0-85138848778

Scopus

1.Division of Physics and Applied Physics,School of Physical and Mathematical Sciences,Nanyang Technological University,Singapore,Singapore
2.Department of Electronic and Electrical Engineering,Southern University of Science and Technology,Shenzhen,China
3.National Engineering Research Center of Electromagnetic Radiation Control Materials,Key Laboratory of Multi-spectral Absorbing Materials and Structures of Ministry of Education,University of Electronic Science and Technology of China,Chengdu,China
4.Interdisciplinary Center for Quantum Information,State Key Laboratory of Modern Optical Instrumentation,ZJU-Hangzhou Global Science and Technology Innovation Center,College of Information Science and Electronic Engineering,ZJU-UIUC Institute,Zhejiang University,Hangzhou,China
5.Research Laboratory for Quantum Materials,Singapore University of Technology and Design,Singapore,Singapore
6.Centre for Disruptive Photonic Technologies,The Photonics Institute,Nanyang Technological University,Singapore,Singapore

Liu，Gui Geng,Gao，Zhen,Wang，Qiang,et al. Topological Chern vectors in three-dimensional photonic crystals[J]. NATURE,2022,609(7929):925-930.

Liu，Gui Geng.,Gao，Zhen.,Wang，Qiang.,Xi，Xiang.,Hu，Yuan Hang.,...&Zhang，Baile.(2022).Topological Chern vectors in three-dimensional photonic crystals.NATURE,609(7929),925-930.

Liu，Gui Geng,et al."Topological Chern vectors in three-dimensional photonic crystals".NATURE 609.7929(2022):925-930.