Skyrmions in Birmingham: from topological models to knotted polarization textures of light

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• Danica Sugic (Theory Group, Birmingham)
• Thursday 27 February 2020, 13:15-14:45
• Theory Library.

If you have a question about this talk, please contact Dr Hannah Price.

Note the new time for Theory seminars this term

Skyrmions were originally proposed as topological models of fundamental particles and nuclei by Tony Skyrme (Professor of the University of Birmingham 1964-1987). Skyrmions have recently received much attention as topological configurations in a variety of physical systems, such as Bose-Einstein condensates, liquid crystals, superconductors, thin magnetic films, and evanescent electromagnetic fields. I will introduce Skyrmions in the polarization distribution of light beams propagating in free-space. These are three-dimensional topological states of light arising in the focal volume of paraxial or tightly-focused ‘dark light’. The intensity of the electromagnetic field is low in the volume in which the Skyrmions are generated. The configuration can be visualised by tracking the lines along which the polarization state of light is constant and takes the form of the celebrated Hopf fibration or its generalisations. The topology is described by the Skyrme number, which counts how many times the optical field wraps around a 3-dimensional sphere. For sufficiently high topological degree, the polarization states are linked and knotted. I will conclude by presenting the experimental measurements of 3D Skyrmions in laser light and a numerical routine to perform the topological analysis of the data based on tetrahedral meshes.

This talk is part of the Theoretical Physics Seminars series.

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