Homoclinic signatures of dynamical localizationR. 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
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 , 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 and . Numerical calculations of kinetic energy and Lyapunov exponents confirm all the theoretical predictions.
05.45.Mt - Quantum chaos; semiclassical methods .
42.50.Vk - Mechanical effects of light on atoms, molecules, electrons, and ions .
© Europhysics Letters Association 2007