Adiabatic representation for the coherent dynamics of<i>N</i>-level systems in intense laser fields

Abstract

The exact adiabatic representation scheme of Nguyen-Dang [J. Chem. Phys. 90, 2657 (1989)] is applied to time evolution of the general laser-driven two- and three-level systems. It leads to exact formal results that do not assume a specific shape of the pulse and do not invoke the rotating-wave approximation (RWA). These results are a generalization of the corresponding RWA results because the former depend on an effective pulse area that varies with the detuning and involves a Rabi frequency modulated by a phase cphi(t). In addition, the exact adiabatic representation scheme is applied to N-level systems exhibiting various dynamic symmetries and, as in the previous cases, leads to results that do not invoke the RWA and depend on an effective pulse area. Time-reversal analysis on two- and three-level systems leads to quantization of the effective pulse area for time-symmetric pulses. This quantization leads to localized asymptotic population distributions.