title: Quantum reversibility and echoes in interacting systems.
abstract: In echo experiments, imperfect time-reversal operations are performed on a subset of the total number of degrees of freedom. To capture the physics of these experiments, we introduce a partial fidelity M(B)(t), the Boltzmann echo, where only part of the system's degrees of freedom can be time reversed. We present a semiclassical calculation of M(B)(t). We show that, as the time-reversal operation is performed more and more accurately, the decay rate of M(B)(t) saturates at a value given by the decoherence rate of the controlled degrees of freedom due to their coupling to uncontrolled ones. We connect these results with NMR spin echo experiments.
authors.affiliation: Département de Physique Théorique, Université de Genève, CH-1211 Genèva 4, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Petitjean
authors.forename: Ph
authors.initials: P
authors.lastname: Jacquod