Egocentric physics : just about Mie

TL;DR

This paper demonstrates that anapole excitations in physics can be explained using a resonant state expansion of Mie theory, avoiding the need for Cartesian toroidal currents, and highlighting a Fano interference effect between modes.

Contribution

It introduces a purely Mie theory-based approach to describe anapole behavior without Cartesian toroidal currents, emphasizing mode interference effects.

Findings

Anapole behavior explained via Fano interference in Mie modes

Resonant state expansion accurately describes anapole excitations

Elimination of scattered field achieved through mode interference

Abstract

We show that the physics of anapole excitations can be accurately described in terms of a resonant state expansion formulation of standard Mie theory without recourse to Cartesian coordinate based `toroidal' currents that have previously been used to describe this phenomenon. In this purely Mie theory framework, the anapole behavior arises as a result of a Fano-type interference effect between different quasi-normal modes of the scatterer that effectively eliminate the scattered field in the associated multipole order.