Time-dependent method in the laser–atom interactions

C. J. Joachain

Bruce W. Shore

In this paper, a practical scheme for computing time-dependent properties, such as excitation probabilities and dipole correlation functions of a multilevel atom strongly excited by a laser in the presence of noise, is described in detail. The method, which is based on the notion of randomly interrupted, multivalued jump processes, can be used to treat laser phase, amplitude, and/or frequency noise, and fluctuating microfields. The method provides analytic expressions, which are based on eigenvalues and eigenvectors of a finite-dimensional matrix, for time dependence and spectral dependence, and it permits computation of time-dependent fluorescence emitted from atoms excited by a noisy laser. The method is illustrated by application to time-dependent spectra.

Jean-Pierre Antoine, Philippe Antoine, Bernard Piraux

Mahmoud Abdel‐Aty, D. A. M. Abo-Kahla, A.‐S. F. Obada

We investigate the dynamical behavior of a three-level moving atom interacting with a laser field. We show that the sensitivity of atomic dynamics can be considerably improved by exploiting the spatial dependence of moving atoms within the framework of the homotopy perturbation method. The dynamics of the system is analyzed as well as the effect of various parameters including detuning and dephasing rate. The spatial dependence approach has the same properties as the time-dependent approach, but it is preferable when the time-scale is very small. The very sensitive dependence and the role of the off-resonant interaction are highlighted.

Jean Dalibard, Claude N. Cohen-Tannoudji

Alexander Blättermann, Christian Ott, Andreas Kaldun +2 more

We demonstrate a two-dimensional time-domain spectroscopy method to extract amplitude and phase modifications of excited atomic states caused by the interaction with ultrashort laser pulses. The technique is based on Fourier analysis of the absorption spectrum of perturbed polarization decay. An analytical description of the method reveals how amplitude and phase information can be directly obtained from measurements. We apply the method experimentally to the helium atom, which is excited by attosecond-pulsed extreme ultraviolet light, to characterize laser-induced couplings of doubly excited states.