Hearing higher-order Weyl exceptional rings in lossy metamaterialsOA

Topological physics integrates the mathematical concept of topology into the physics framework to characterize quantum phases of matter and explore their applications in materials science.In Hermitian regimes,topological semimetals with nontrivial bulk band crossings have attracted sustained interest[1].For instance,Weyl semimetals feature Weyl degeneracy points in three-dimensional space,which carry topological charges characterized by Chern numbers and guarantee Fermi-arc surface states.Crucially,Weyl points may further exhibit higher-order topological properties protected via quantized bulk polarizations or multipole moments,thereby enabling the formation of topological hinge states.