Seminario di fisica matematica
ore
14:30
presso Aula Arzelà
The spectrum of non-selfadjoint operators can be highly unstable even under very
small perturbations. This phenomenon is referred to as "pseudospectral effect".
Traditionally this pseudosepctral effect was considered a drawback since it can be
the source of immense numerical errors, as shown for instance in the works of
L. N. Trefethen. However, this pseudospectral effect can also be the source of many new insights.
A line of works by Hager, Bordeaux-Montrieux, Sjöstrand, Christiansen and Zworski
exploits the pseudospectral effect to show that the (discrete) spectrum of a large
class of non-selfadjoint pseudo-differential operators subject to a small random
perturbation follows a Weyl law with probability close to one.
In this talk we will discuss some recent results on the macroscopic and microscopic
distribution of eigenvalues as well as eigenvector localization and delocalization
phenomena of non-selfadjoint operators subject to small random perturbations.