Mardi 3 février 2026 à 11h00, amphi F. Canac, LMA
Abstract: Open systems are ubiquitous in physics, arising whenever energy, matter, or information is exchanged with an environment and their spectral properties play a central role in determining dynamical behaviour across a wide range of disciplines. It has been shown that the spectral properties of open systems can be extremely sensitive to perturbations, leading to the phenomena of spectral instability: a small modification of the system may change drastically its resonant spectrum. In this talk, we’ll investigate how localized perturbations affect the complex spectrum of resonances of one-dimensional open systems. We’ll reveal that the spectrum deforms in a smooth and continuous manner, tracing well-defined trajectories in the complex plane. Adopting a dynamical systems perspective, we’ll show that those trajectories are governed by attracting and repelling spectral points that depend only on the unperturbed system. The presented framework provides a unified and intuitive interpretation of spectral instabilities in open systems and is broadly applicable to resonant phenomena in wave physics.
Théo Torres - Laboratoire Interdisciplinaire Carnot de Bourgogne