Kruk, SergeyGao, WenlongChoi, Duk-YongZentgraf, ThomasZhang, ShuangKivshar, Yuri2023-02-261530-6984http://hdl.handle.net/1885/286420Topological states of light represent counterintuitive optical modes localized at boundaries of finite-size optical structures that originate from the properties of the bulk. Being defined by bulk properties, such boundary states are insensitive to certain types of perturbations, thus naturally enhancing robustness of photonic circuitries. Conventionally, the N-dimensional bulk modes correspond to (N - 1)-dimensional boundary states. The higher-order bulk-boundary correspondence relates N-dimensional bulk to boundary states with dimensionality reduced by more than 1. A special interest lies in miniaturization of such higher-order topological states to the nanoscale. Here, we realize nanoscale topological corner states in metasurfaces with C6-symmetric honeycomb lattices. We directly observe nanoscale topology-empowered edge and corner localizations of light and enhancement of light-matter interactions via a nonlinear imaging technique. Control of light at the nanoscale empowered by topology may facilitate miniaturization and on-chip integration of classical and quantum photonic devices.S.K. thanks Kirill Koshelev for an expert advice. Y.K. thanks Alexander Poddubny for encouraging discussions. W.G. is indebted to Daria Smirnova for her generous help and useful advice. S.K. acknowledges support from the Alexander von Humboldt Foundation. D.Y.C. acknowledges the use of the Australian National Fabrication Facility of the ACT Node.and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreements 724306 and 648783).application/pdfen-AU© 2021 The authorsTopologycorner statesnonlinear opticsMie resonancesmeta surfaces202110.1021/acs.nanolett.1c004492021-12-19