Polarization of light can form skyrmionic textures, akin to nonlinear solitons in condensed matter, yet their disparate physical context has motivated extensive debate regarding their stability. Here we show that the topological charge of such structures (skyrmion number) changes when an arbitrarily small perturbation splits coalescent phase singularities. In a superposition of two vortex beams, the skyrmion number generally only depends on the higher order topological charge $\lrr{Q_{\rm sk}=\max\lr{\ell_2,\ell_1}}$ rather than the difference of charges of the vortices in superposition $\lrr{Q_{\rm sk}=\ell_2-\ell_1}$, which only holds in the absence of perturbation. These results have significant implications for polarization structures with wavelength-scale localization and those experiencing complex aberrations.
Periodic skyrmionic textures via conformal cartographic projections
Aix Marseille Univ., CNRS, Centrale Marseille, Institut Fresnel（艾克斯-马赛大学，法国国家科学研究中心，马赛中央理工学院，费涅尔研究所）；Instituto de Bioingeniería, Universidad Miguel Hernández de Elche（生物工程学院，埃尔切米格尔·埃尔南德斯大学）；The Institute of Optics, University of Rochester（罗切斯特大学光学研究所）；Center for Coherence and Quantum Optics, University of Rochester（罗切斯特大学相干与量子光学中心）；Laboratory for Laser Energetics, University of Rochester（罗切斯特大学激光能量学实验室）
Photonic torons, topological phase transition and tunable spin monopoles
Harbin University of Science and Technology（哈尔滨理工大学）；Nanyang Technological University（南洋理工大学）；National University of Singapore（新加坡国立大学）；Stanford University（斯坦福大学）
Skyrmion topology of scalar waves in real and momentum space
Wyant College of Optical Sciences, University of Arizona（亚利桑那大学怀特光学科学学院）；Paderborn University（帕德博恩大学）；Institute for Photonic Quantum Systems (PhoQS), Paderborn University（帕德博恩大学光子量子系统研究所）；University of Stuttgart（斯图加特大学）；Department of Physics, University of Arizona（亚利桑那大学物理系）
Free-Space Propagation and Skyrmion Topology of Toroidal Electromagnetic Pulses
Institute of Applied Physics, University of Electronic Science and Technology of China（电子科技大学应用物理研究所）；Yangtze Delta Region Institute (Huzhou), University of Electronic Science and Technology of China（电子科技大学长三角研究院（湖州））；Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University（南洋理工大学物理与数学科学学院物理学与应用物理学部）；Centre for Disruptive Photonic Technologies, The Photonics Institute, Nanyang Technological University（南洋理工大学光子研究院破坏性光子技术研究中心）；Optoelectronics Research Centre & Centre for Photonic Metamaterials, University of Southampton（南安普顿大学光电子研究中心及光子超材料中心）
Quantum Skyrmions in Mixed States of Light and Their Nested Topology
Technion - Israel Institute of Technology（以色列理工学院）；Stanford University（斯坦福大学）；Institute of Science and Technology Austria (ISTA)（奥地利科学技术研究所）；Massachusetts Institute of Technology（麻省理工学院）
