title: Quantum reversibility: is there an echo?
abstract: We study the possibility to undo the quantum mechanical evolution in a time reversal experiment. The naive expectation, as reflected in the common terminology ("Loschmidt echo"), is that maximum compensation results if the reversed dynamics extends to the same time as the forward evolution. We challenge this belief and demonstrate that the time t(r) for maximum return probability is in general shorter. We find that t(r) depends on lambda=epsilon(evol)/epsilon(prep), being the ratio of the error in setting the parameters (fields) for the time-reversed evolution to the perturbation which is involved in the preparation process. Our results should be observable in spin-echo experiments where the dynamical irreversibility of quantum phases is measured.
authors.affiliation: Max-Planck-Institut für Strömungsforschung und Fakultät Physik der Universität Göttingen, Bunsenstrasse 10, D-37073 Göttingen, Germany.
authors.forename: Moritz
authors.initials: M
authors.lastname: Hiller
authors.forename: Tsampikos
authors.initials: T
authors.lastname: Kottos
authors.forename: Doron
authors.initials: D
authors.lastname: Cohen
authors.forename: Theo
authors.initials: T
authors.lastname: Geisel