# Total helicity of electromagnetic fields and matter

Fernandez-Corbaton, Ivan

##### Abstract:
The electromagnetic helicity of the free electromagnetic field and the static magnetic helicity are shown to be two different embodiments of the same physical quantity, the total helicity. The total helicity is the sum of two terms: A term that measures the difference between the number of left-handed and right-handed photons of the free field, and another term that measures the screwiness of the static magnetization density in matter. Each term is the manifestation of the total helicity in different frequency regimes: $\omega>0$ and $\omega=0$, respectively. This unification establishes the theoretical basis for studying the conversion between the two embodiments of total helicity upon light-matter interaction.

 Zugehörige Institution(en) am KIT Institut für Nanotechnologie (INT) Publikationstyp Zeitschriftenaufsatz Publikationsdatum 01.02.2021 Sprache Englisch Identifikator ISSN: 2469-9950, 2469-9969 KITopen-ID: 1000129279 HGF-Programm 43.32.02 (POF IV, LK 01) Designed Optical Materials Erschienen in Physical review / B Verlag American Physical Society (APS) Band 103 Heft 5 Seiten Art.-Nr.: 054406 Schlagwörter Helicity, non-collinear magnetism, light-matter interactions Nachgewiesen in Dimensions
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