Surface states ensured by a synthetic Weyl point in one-dimensional plasmonic dielectric crystals with broken inversion symmetry

Abstract

Weyl points, i.e., peculiar nodal degenerate points in three-dimensional reciprocal space, carry topological charges, therefore giving rise to many intriguing phenomena including topologically protected surface states and chiral anomaly. More importantly, the concept of the Weyl point can be applied in systems with reduced geometrical dimensionality by means of synthetic dimension. Such generalized synthetic Weyl points therefore provide a versatile platform to explore the Weyl-point physics in one or two-dimensional structures. In this work, we study the synthetic Weyl points in one-dimensional plasmonic-dielectric crystals with broken inversion symmetry and further demonstrate that the synthetic Weyl points can ensure the emergence of topological interface states. Instead of using the Zak phase, the emergence of a Weyl point in synthetic space is helpful to understand the underlying physics and the topological properties of the interface states in one-dimensional crystals with broken inversion symmetry. Due to the opposite sign of the surface impedance for plasmonic and dielectric cover medium, the surface states demonstrate distinct properties and locate in separated parameter space regions. Our results show that the synthetic Weyl point provides a potential approach for studying novel electromagnetic modes and facilitates the formation of topologically protected interface states in systems with reduced geometrical dimensions.