Description and Control of Strong-Field Electronic Dynamics

Electronic wave functions are responsible for the properties of atoms, molecules and clusters. It is therefore of special importance to describe, and, as a next step observe and control them. The timescale on which electronic dynamics takes place is on the order of several hundreds of attoseconds - a domain which has recently become accessible experimentally. Strong laser fields acting on quantum systems may ionize them and thereby create electronic wave packets. The liberated electron follows the optical oscillations of the laser field and may revisit the parent ion. While atom- electron recollision can be found in textbooks, the process of strong field recollision itself is not fully understood. As the electron which collides originates from the same parent ion, correlation effects are important in this process. The emission of high order harmonics radiation is a result of this coherent process. Within one part of the project the role and extent of correlation and entanglement is examined. Looking at the phase space distribution of the recolliding electron before, during and after the recollision, we will improve the understanding of the physical picture of this fundamental process. In a next step, applying quantum control algorithms, we plan to manipulate and steer the electronic recollisional dynamics. Thereby, laser parameters as chirp, intensity and ellipticity will be examined. Taking molecular hydrogen as an example, the correlated dynamics of the second electron will be regarded and analyzed in terms of controllability and correlation. The second part of the project will focus on conical intersections (in one dimension these are curve crossings), which are of fundamental importance in chemistry and biology. Spectroscopically, these regions were only accessible by vibrational spectroscopy or absorption/emission spectroscopy. Within the second part of this project, we will model the coupled nuclear-electronic dynamics in the vicinity of curve-crossing regions and analyze the information which can be obtained by highorder harmonic spectra, as they are by nature sensitive to the phase and symmetry of the electronic state they originate from.