Issue
EPL
Volume 77, Number 3, February 2007
Article Number 30001
Number of page(s) 5
Section General
DOI http://dx.doi.org/10.1209/0295-5075/77/30001
Published online 25 January 2007
EPL, 77 (2007) 30001
DOI: 10.1209/0295-5075/77/30001

Homoclinic signatures of dynamical localization

R. Chacón

Departamento de Física Aplicada, Escuela de Ingenierías Industriales, Universidad de Extremadura, Apartado Postal 382, E-06071 Badajoz, Spain


received 29 August 2006; accepted in final form 28 November 2006; published February 2007
published online 25 January 2007

Abstract
It is demonstrated that the oscillations in the width of the momentum distribution of atoms moving in a phase-modulated standing light field, as a function of the modulation amplitude $\lambda $, are correlated with the variation of the chaotic layer width in energy of an underlying effective pendulum. The maximum effect of dynamical localization and the nearly perfect delocalization are associated with the maxima and minima, respectively, of the chaotic layer width. It is also demonstrated that kinetic energy is conserved as an almost adiabatic invariant at the minima of the chaotic layer width, and that the system is accurately described by delta-kicked rotors at sufficiently large zeros of the Bessel functions $J_{0}(\lambda)$ and $J_{1}(\lambda)$. Numerical calculations of kinetic energy and Lyapunov exponents confirm all the theoretical predictions.

PACS
05.45.Mt - Quantum chaos; semiclassical methods .
42.50.Vk - Mechanical effects of light on atoms, molecules, electrons, and ions .

© Europhysics Letters Association 2007