2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/123525We study the mechanisms responsible for quantum diffusion in the quasiperiodic kicked rotor. We report experimental measurements of the diffusion constant on the atomic version of the system and develop a theoretical approach (based on the Floquet theorem) explaining the observations, especially the ``sub-Fourier'' character of the resonances observed in the vicinity of exact periodicity, i.e. the ability of the system to distinguish two neighboring driving frequencies in a time shorter than the inverse of the difference of the two frequencies.7 pages, 4 figures, accepted for publication in Europhysics LettersQuantum PhysicsChaotic DynamicsAtomic Physicstext