Time-domain excitation of finite-lifetime resonances and their exceptional points
Phys. Rev. A 114, 033518 – Published 16 September, 2026
DOI: https://doi.org/10.1103/vkwr-kgj9
Abstract
Resonances associated with complex-frequency poles are ubiquitous across physics and can arise in any open system, ranging from subwavelength particles and cavities to biological structures. When two such resonances coalesce, they form exceptional points (EPs), non-Hermitian singularities known to produce unusual spectral and dynamical behavior. However, the dynamics of the response of such resonances and exceptional points to a complex-frequency drive has remained largely unexplored. Here, we experimentally observe the temporal response of complex-frequency resonances and theoretically study it for exceptional points, demonstrating that the passive system's initial response for a decaying drive grows linearly, with enhanced growth at EPs. Closed-form theory for general resonators, extended to higher-order modes, predicts efficient power transfer with and scaling for complex single poles and EPs, respectively, at all times. We analyze these effects in subwavelength optical scatterers and experimentally in an electrical circuit analogue, with excellent agreement, and explore configurations that capture EP-enhanced growth.
