---
abstract: |
    In nanophotonics, multipole approach has become an indispensable theoretical framework for analyzing subwavelength meta-atoms and their radiation properties. Thus far, induced multipole moments have frequently used to illustrate the radiating properties of the meta-atoms, but they are excited at a specific illumination and do not fully represent anisotropic meta-atoms. On the other hand, dynamic polarizability ($\boldsymbol{\alpha}$) tensors contain complete scattering information of the meta-atoms, but have not often been considered due to complicated retrieval procedures. In this study, we suggest that exact higher-order $\boldsymbol{\alpha}$-tensor can be efficiently obtained from $\mathbf{T}$-matrix using simple basis transformation. These higher-order $\boldsymbol{\alpha}$-tensors are necessary to describe recently reported coupled plasmonic and high-refractive-index particles, which we demonstrate from their retrieved $\boldsymbol{\alpha}$-tensors. Finally, we show that description of meta-atoms using $\boldsymbol{\alpha}$-tensors incorporated with multiple-scattering theory vastly extends the applicability of the multipole approach in nanophotonics, allowing accurate and efficient depiction of complicated, random, multi-scale systems.

    Usage

    :   Preprint.

author:
- Jungho Mun
- Sunae So
- Jaehyuck Jang
- Junsuk Rho
bibliography:
- 'apssamp.bib'
title: 'Describing meta-atoms using the exact higher-order polarizability tensors'
---

Introduction
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Under the paradigm of metamaterial, its constituent meta-atoms and their configurations determine the material properties. The meta-atoms have 