title: Non-Markovian behavior of small and large complex quantum systems.
abstract: The channel induced by a complex system interacting strongly with a qubit is calculated exactly under the assumption of randomness of its eigenvectors. The resulting channel is represented as an isotropic time-dependent oscillation of the Bloch ball, leading to non-Markovian behavior, even in the limit of infinite environments. Two contributions are identified: one due to the density of states and the other due to correlations in the spectrum. Prototype examples, one for chaotic and the other for regular dynamics are explored.
authors.affiliation: Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico.
authors.forename: Marko
authors.initials: M
authors.lastname: Žnidarič
authors.forename: Carlos
authors.initials: C
authors.lastname: Pineda
authors.forename: Ignacio
authors.initials: I
authors.lastname: García-Mata