Transient phase-space localization

Abstract

We show that dynamics can, in general, be used to enhance the coherence of a Hamiltonian ensemble and we analyze the transient coherence using the coarse-grained entropy. We illustrate this concept using a Rydberg atom subject to an impulsive momentum transfer or ``kick.'' Classical simulations predict that the wave packet generated by the kick undergoes strong transient phase-space localization, which forms an excellent starting point for its further control and manipulation. Moreover, we show that such localized states can be ``trapped'' for extended periods using a train of subsequent kicks.