Effective-action formulation of k-odd bianisotropy and unidirectional polarization rotation in nonlocal temporal metamaterials
Abstract
We derive the effective action of temporal metamaterials up to first order in spatial derivatives through a multiscale analysis of the electromagnetic Lagrangian density. We show that the first-order spatial correction gives rise to an effective bianisotropic coupling tensor that is odd in the wavevector k. Remarkably, chiral, pseudochiral, and omega-type bianisotropic responses emerge as distinct directional manifestations of a single nonlocal coupling tensor, even when the underlying electric and magnetic response tensors remain symmetric. Furthermore, we establish a framework for analyzing Lorentz reciprocity based on the Hessian of the effective action. We demonstrate that Lorentz reciprocity is preserved in the presence of omega-type coupling but is broken when chiral or pseudochiral coupling emerges. This nonreciprocity manifests as the unidirectional rotations of normalized Stokes vectors incurred by Floquet-engineered chirality and pseudochirality.
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BibTeX
@misc{wang2026effectiveaction,
title = {{Effective-action formulation of $\mathbfk$-odd bianisotropy and unidirectional polarization rotation in nonlocal temporal metamaterials}},
author = {Neng Wang and Guo Ping Wang},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.31022},
eprint = {2610.31022},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.31022},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Effective-action formulation of k-odd bianisotropy and unidirectional polarization rotation in nonlocal temporal metamaterials
AU - Neng Wang
AU - Guo Ping Wang
PY - 2026
DA - 2026/10/22
PB - arXiv
DO - 10.48550/arxiv.2610.31022
UR - https://arxiv.org/abs/2610.31022
AB - We derive the effective action of temporal metamaterials up to first order in spatial derivatives through a multiscale analysis of the electromagnetic Lagrangian density. We show that the first-order spatial correction gives rise to an effective bianisotropic coupling tensor that is odd in the wavevector k. Remarkably, chiral, pseudochiral, and omega-type bianisotropic responses emerge as distinct directional manifestations of a single nonlocal coupling tensor, even when the underlying electric and magnetic response tensors remain symmetric. Furthermore, we establish a framework for analyzing Lorentz reciprocity based on the Hessian of the effective action. We demonstrate that Lorentz reciprocity is preserved in the presence of omega-type coupling but is broken when chiral or pseudochiral coupling emerges. This nonreciprocity manifests as the unidirectional rotations of normalized Stokes vectors incurred by Floquet-engineered chirality and pseudochirality.
ER -