Observation of vortex-string chiral modes in metamaterials

TL;DR

This paper reports the experimental observation of vortex-string chiral modes in a metamaterial system, confirming their topological nature and potential applications in signal processing.

Contribution

It demonstrates the first experimental detection of vortex-string chiral modes using a Yang-monopole phononic metamaterial, bridging astrophysical concepts and engineered systems.

Findings

Observation of linear dispersion of vortex-string modes

Confirmation of topological chiral-anomaly states

Potential for topological fibre applications

Abstract

As a hypothetical topological defect in the geometry of spacetime, vortex strings play a crucial role in shaping the clusters of galaxies that exist today, and their distinct features can provide observable clues about the early universe's evolution. A key feature of vortex strings is that they can interact with Weyl fermionic modes and support topological chiral-anomaly states with massless dispersions at the core of strings. To date, despite many attempts to detect vortex strings in astrophysics or to emulate them in artificially created systems, observation of these topological vortex-string chiral modes remains experimentally elusive. Here we report the experimental observation of such vortex-string chiral modes using a metamaterial system. This is implemented by inhomogeneous perturbation of a Yang-monopole phononic metamaterial. The measured linear dispersion and modal profiles confirm the existence of topological modes bound to and propagating along the vortex string with the chiral anomaly. Our work not only provides a platform for studying diverse cosmic topological defects in astrophysics but also offers intriguing device applications as topological fibres in signal processing and communication techniques.