Ultrafast dynamics optimal control

Other prominent examples are theoretical proposals for different optical control schemes using laser field parameters for the manipulation of ultrafast process pioneered by Rice and Tannor, Shapiro and Brumer, and Peirce, Dahleh, and Rabitz [2, 56-61]. They stimulated control experiments that were carried out first on simple systems such as metallic dimers and trimers [62-84], and later on more complex systems [23-25, 43, 85-89], confirming theoretically proposed concepts. Since tailored laser pulses have the ability to select pathways that optimally lead to the chosen target, their analysis should allow one to determine the mechanism of the processes and to provide the information about the selected pathways (inversion problem). Therefore, theoretical approaches are needed, which are capable of designing interpretable optimal laser pulses for complex systems (e.g., clusters or biomolecules) by establishing the connection between the underlying dynamical processes and their shapes. In this case, the optimal control can be used as a tool for the analysis. 

Analysis and control of ultrafast processes in atomic clusters in the size regime in which each atom counts are of particular importance from a conceptual point of view and for opening new perspectives for many applications in the future. Simultaneously, this research area calls for the challenging development of theoretical and computational methods from different directions, including quantum chemistry, molecular dynamics, and optimal control theory, removing borders between them. Moreover, it provides stimulation for new experiments. 

Figure 6.2 Steering of photochemical reactions by coherent control of ultrafast electron dynamics in molecules by shaped femtosecond laser pulses. Ultrafast excitation of electronic target states in molecules launches distinct nuclear dynamics, which eventually lead to specific outcomes of the photochemical reaction. The ability to switch efficiently between different electronic target channels, optimally achieved by turning only a single control knob on the control field, provides an enhanced flexibility in the triggering of photochemical events, such as fragmentation, excited state vibration, and isomerization.

Polyatomic molecules are characterized by complex internal motions leading to several possible rearrangements. With the advent of ultrafast lasers, much hope arose for achieving mode selectivity in chemical reactions based on the interaction between the laser pulses and the dynamics of the molecule. In the quest to steer complex systems, an especially attractive control scheme is the adaptive optimal... 

The general concept of the optimal dynamic discrimination (ODD) has been recently proposed by Rabitz and Wolf et al. [60,61]. The idea of the ODD relies on a theoretical analysis which has shown that quantum systems differing even infinitesimally may be distinguished by means of their dynamics when a suitably shaped ultrafast control field is applied. In the case of the two similar flavins (differing only by replacement of H by PO(OH)2 in the side chain) the controlled depletion of the fluorescence signal has been used as a discriminating observable... 

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