Water-Wave Vortices and Skyrmions

TL;DR

This paper explores topological wave structures such as vortices and skyrmions in water-surface waves, revealing their formation, properties, and potential applications in microfluidics and wave physics.

Contribution

It is the first comprehensive study of topological water-wave structures, including vortices, skyrmions, and merons, in classical water waves.

Findings

Water-wave vortices with quantized angular momentum are demonstrated.

Skyrmion and meron lattices can be formed by water-surface displacements.

Topological water-wave structures can be generated in linear interference experiments.

Abstract

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, (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.