Water-Wave Vortices and Skyrmions

Topological wave structures—phase vortices, skyrmions, merons, etc.—are attracting enormous attention in a variety of quantum and classical wave fields. Surprisingly, these structures have never been properly explored in the most obvious example of classical waves: water-surface (gravity-capillary) waves. Here, we fill this gap and describe (i) water-wave vortices of different orders carrying quantized angular momentum with orbital and spin contributions, (ii) skyrmion lattices formed by the instantaneous displacements of the water-surface particles in wave interference, and (iii) meron (half-skyrmion) lattices formed by the spin-density vectors, as well as (iv) spatiotemporal water-wave vortices and skyrmions. We show that all these topological entities can be readily generated in linear water-wave interference experiments. Our findings can find applications in microfluidics and show that water waves can be employed as an attainable playground for emulating universal topological wave phenomena.Received 10 August 2023Accepted 14 November 2023DOI:https://doi.org/10.1103/PhysRevLett.132.054003© 2024 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasAngular momentum of lightFluid-particle interactionsHydrodynamic wavesSkyrmionsSurface gravity wavesVortex flowsPhysical SystemsWaterFluid DynamicsAtomic, Molecular & Optical