31 may 2019 -- 13:00
University of Hradec Králové
Abstract.
An interesting question is to count the number of resolvent resonances of quantum graphs which are encircled in the circle of radius $R$ in the complex plane in the limit for $R\to \infty$. Davies and Pushnitski found that for some graphs this number grows with $R$ slower than one would expect from the Weyl asymptotics. We will introduce criteria on how to distinguish the non-Weyl graphs from the Weyl ones and explain why this phenomenon occurs. Recently, this behaviour was experimentally verified using microwave graphs; we will give details of this experiment.