Discovery of a maximally charged Weyl point

Qiaolu Chen; Fujia Chen; Yuang Pan; Chaoxi Cui; Qinghui Yan; Li Zhang; Zhen Gao; Shengyuan A Yang; Zhi-Ming Yu; Hongsheng Chen; Baile Zhang; Yihao Yang

doi:10.1038/s41467-022-34978-z

Discovery of a maximally charged Weyl point

Nat Commun. 2022 Nov 30;13(1):7359. doi: 10.1038/s41467-022-34978-z.

Authors

Qiaolu Chen^{1

2

3}, Fujia Chen^{1

2

3}, Yuang Pan^{1

2

3}, Chaoxi Cui^{4

5}, Qinghui Yan^{1

2

3}, Li Zhang^{1

2

3}, Zhen Gao⁶, Shengyuan A Yang⁷, Zhi-Ming Yu^{8

9}, Hongsheng Chen^{10

11

12}, Baile Zhang^{13

14}, Yihao Yang^{15

16

17}

Affiliations

¹ Interdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027, China.
² International Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400, China.
³ Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099, China.
⁴ Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China.
⁵ Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, China.
⁶ Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
⁷ Research Laboratory for Quantum Materials, Singapore University of Technology and Design, Singapore, 487372, Singapore.
⁸ Centre for Quantum Physics, Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE), School of Physics, Beijing Institute of Technology, Beijing, 100081, China. zhiming_yu@bit.edu.cn.
⁹ Beijing Key Laboratory of Nanophotonics and Ultrafine Optoelectronic Systems, School of Physics, Beijing Institute of Technology, Beijing, 100081, China. zhiming_yu@bit.edu.cn.
¹⁰ Interdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027, China. hansomchen@zju.edu.cn.
¹¹ International Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400, China. hansomchen@zju.edu.cn.
¹² Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099, China. hansomchen@zju.edu.cn.
¹³ Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore, 637371, Singapore. blzhang@ntu.edu.sg.
¹⁴ Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University, 50 Nanyang Avenue, Singapore, 639798, Singapore. blzhang@ntu.edu.sg.
¹⁵ Interdisciplinary Centre for Quantum Information, State Key Laboratory of Modern Optical Instrumentation, ZJU-Hangzhou Global Scientific and Technological Innovation Centre, Zhejiang University, Hangzhou, 310027, China. yangyihao@zju.edu.cn.
¹⁶ International Joint Innovation Centre, Key Lab. of Advanced Micro/Nano Electronic Devices & Smart Systems of Zhejiang, The Electromagnetics Academy at Zhejiang University, Zhejiang University, Haining, 314400, China. yangyihao@zju.edu.cn.
¹⁷ Jinhua Institute of Zhejiang University, Zhejiang University, Jinhua, 321099, China. yangyihao@zju.edu.cn.

Abstract

The hypothetical Weyl particles in high-energy physics have been discovered in three-dimensional crystals as collective quasiparticle excitations near two-fold degenerate Weyl points. Such momentum-space Weyl particles carry quantised chiral charges, which can be measured by counting the number of Fermi arcs emanating from the corresponding Weyl points. It is known that merging unit-charged Weyl particles can create new ones with more charges. However, only very recently has it been realised that there is an upper limit - the maximal charge number that a two-fold Weyl point can host is four - achievable only in crystals without spin-orbit coupling. Here, we report the experimental realisation of such a maximally charged Weyl point in a three-dimensional photonic crystal. The four charges support quadruple-helicoid Fermi arcs, forming an unprecedented topology of two non-contractible loops in the surface Brillouin zone. The helicoid Fermi arcs also exhibit the long-pursued type-II van Hove singularities that can reside at arbitrary momenta. This discovery reveals a type of maximally charged Weyl particles beyond conventional topological particles in crystals.

Abstract

Grants and funding