Beyond optical chirality density: tensor-based description of electromagnetic chirality

TL;DR

This paper introduces tensor-based measures of electromagnetic chirality to better describe chiral fields in anisotropic media, extending beyond traditional scalar density measures.

Contribution

It proposes a set of tensor quantities for electromagnetic chirality based on Lipkin formalism, providing a richer description in complex media.

Findings

Tensor measures reveal multiple aspects of electromagnetic chirality.

Tensor components have clear physical interpretations.

Approach enhances understanding of chiral field-matter interactions in anisotropic environments.

Abstract

Optical chirality density is widely used as a scalar measure of the chiral properties of electromagnetic fields and their interaction with matter. However, in anisotropic and structured media, a single scalar quantity is generally insufficient to capture the full complexity of chiral field-matter coupling. In this work, we go beyond the conventional optical chirality density and introduce a set of tensor measures of electromagnetic chirality based on the Lipkin formalism. These tensor quantities provide a richer and more physically transparent description of chiral electromagnetic fields, particularly in an anisotropic environment. The physical meaning of individual tensor components is discussed, and their role in characterizing different aspects of electromagnetic chirality is clarified. The proposed approach reveals multiple, complementary measures of field chirality that naturally emerge in anisotropic cases and are directly relevant to the interaction of structured electromagnetic fields with matter.