Total invisibility of compound particles from the perspective of multipole expansion
Phys. Rev. B 113, 045145 – Published 23 January, 2026
DOI: https://doi.org/10.1103/kqvv-3fbx
Abstract
Fifty years ago, Devaney and Wolf formulated five groundbreaking invisibility theorems describing nonradiating sources and invisible particles. From the perspective of multipole decomposition, these theorems establish the conditions on the configurations of currents and electromagnetic fields that define nonradiating sources. Although these theorems are general, they encounter limitations when applied to real sources, since it is impossible to suppress all radiated harmonics in practice. However, these limitations can be mitigated in compound particles composed of two or more components. In this paper, we extend these concepts by formulating invisibility theorems for bulk compound sources and by establishing the conditions for total invisibility from the viewpoint of multipole expansion. We demonstrate that the all multipole moments of compound invisible system can be completely suppressed for all interfering multipoles, originating from polarization and magnetization parts of current density excited within the structure. We employ an extended multipole expansion framework that explicitly separates the polarization and magnetization contributions, and discuss the resulting invisibility effects. We provide examples of totally invisible spheres and core-shell dielectric/magnetic particles with identical permittivity and permeability. Our approach offers insights into the design of nonradiating and invisible structures for photonic and metamaterial applications.
