Quantum Coherent Control of Atoms in a Classically Chaotic Regime

Paul W. Brumer, Jiangbin Gong

Evgeny A. Shapiro, Michael Spanner, Misha Ivanov

We consider the quantum dynamics of the kicked rotor model in the regime where the last stable resonance islands in the classical phase space disappear. It is found that phase space regions with lower local diffusion rates are able to preserve quantum population. The low-diffusion regions can be moved through phase space in a quasi-adiabatic way by smoothly varying the parameters of the kicking field. With appropriately chosen time-scales for the variation of the field parameters, wave packets initially localized around the low-diffusion areas remain localized around these regions as the regions are moved. The wave packets can then be carried to desired regions of space despite the predominantly chaotic character of the classical phase space. We also comment on the Gong–Brumer scenario of coherent control of quantum chaotic diffusion [Phys. Rev. Lett. 86 1741 (2001)]. While our phase-space inspired control has a clear semiclassical interpretation, it appears that the Gong–Brumer control has a predominantly quantum origin. Furthermore, it is found that our control over wave packet localization disappears in the deeply chaotic regime, while the Gong–Brumer control over the chaotic diffusion persists in this regime but becomes increasingly unstable with increasing chaoticity.

Dimitrios Charalambidis, Natalia E. Karapanagioti, D. Xenakis +8 more

Rui-hua Xie, Gong-ou Xu

Dynamical symmetry and squeezing effect have been investigated in a classically chaotic quantum system [M. Ku\ifmmode \acute{s}\else \'{s}\fi{}, Phys. Rev. Lett. 54, 1343 (1985)] when it is restricted to the following initial condition: the atom in its SU(2) coherent state and the field in the vacuum state. In the regime of classically regular motion, dynamical symmetry and squeezing effects have been exposed under proper choice of the atomic coherent state; but, in that of classically chaotic motion, the symmetry is destroyed thoroughly and the squeezing effect disappears. \textcopyright{} 1996 The American Physical Society.

Warren S. Warren

Chitra Rangan