Temporal scattering at irremovable exceptional points in lossless Drude media
Phys. Rev. A 113, 013510 – Published 6 January, 2026
DOI: https://doi.org/10.1103/2bkl-1gld
Abstract
We investigate temporal scattering in lossless Drude media and reveal an overlooked role of the zero-frequency flatband associated with static polarization charge. This flatband forms an exceptional line spanning all wave numbers and can be directly excited during temporal scattering at photonic time interfaces, generating nonpropagating static fields alongside the usual reflected and transmitted waves. Eigenvector coalescence at the corresponding exceptional points leads to two distinctive features absent in previously studied systems: a static mode whose amplitude increases linearly with time and an additional static component arising from the system's generalized eigenvector. Remarkably, these effects occur without violating total energy conservation, underscoring the Hermitian nature of the dynamics. Our findings present an alternative physical picture of temporal scattering, sharply distinct from that in dispersionless and Lorentz-dispersive media.
