2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/129221Properties of a quantum mushroom billiard in the form of a superconducting microwave resonator have been investigated. They reveal unexpected nonuniversal features such as, e.g., a supershell effect in the level density and a dip in the nearest-neighbor spacing distribution. Theoretical predictions for the quantum properties of mixed systems rely on the sharp separability of phase space - an unusual property met by mushroom billiards. We however find deviations which are ascribed to the presence of dynamic tunneling.4 pages, 7 .eps-figuresChaotic DynamicsStatistical MechanicsQuantum Physicstext