Ultrafast laser control of electron dynamics in atoms, molecules and solids

Wollenhaupt, M.; Baumert, Thomas

doi:10.1039/c1fd00109d

Cited by 74 publications

(54 citation statements)

References 117 publications

(151 reference statements)

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“…The question of why only specific resonances experience the phase shift cannot be answered at this point due to the lack of detailed information about the dye molecule. With more such knowledge becoming available, e.g., from quantum-chemical calculations, the general model developed here should help to test our understanding of molecules in strong fields, and thus pave a route to comprehensive control of molecular excited states by intense laser fields (20,(46)(47)(48)(49).…”

Section: Numerical Model and Discussionmentioning

confidence: 99%

Signatures and control of strong-field dynamics in a complex system

Meyer

Liu

Müller

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Controlling chemical reactions by light, i.e., the selective making and breaking of chemical bonds in a desired way with strong-field lasers, is a long-held dream in science. An essential step toward achieving this goal is to understand the interactions of atomic and molecular systems with intense laser light. The main focus of experiments that were performed thus far was on quantum-state population changes. Phase-shaped laser pulses were used to control the population of final states, also, by making use of quantum interference of different pathways. However, the quantum-mechanical phase of these final states, governing the system's response and thus the subsequent temporal evolution and dynamics of the system, was not systematically analyzed. Here, we demonstrate a generalized phase-control concept for complex systems in the liquid phase. In this scheme, the intensity of a control laser pulse acts as a control knob to manipulate the quantum-mechanical phase evolution of excited states. This control manifests itself in the phase of the molecule's dipole response accessible via its absorption spectrum. As reported here, the shape of a broad molecular absorption band is significantly modified for laser pulse intensities ranging from the weak perturbative to the strongfield regime. This generalized phase-control concept provides a powerful tool to interpret and understand the strong-field dynamics and control of large molecules in external pulsed laser fields. C an we find universal concepts to understand and control the response of atoms and molecules in interactions with strong laser fields? This question is at the heart of a vast number of experiments in time-resolved spectroscopy (1-30). The wide range of light sources spanning the spectral range from the X-ray (e.g., free-electron laser sources, synchrotrons) over the visible (conventional laser systems) to the far-infrared regime and covering the temporal range from nanosecond down to attosecond time scales created a wealth of new physics insight into quantum mechanisms, however mostly of simple systems in the gas phase (1-4). In chemistry, the generation of femtosecond laser pulses enabled the investigation of wave packet dynamics in molecules, as the induced vibrations occur on these time scales. Experiments focusing on, for instance, dissociation reactions, atom transfer, isomerization, or solvation dynamics have led to a deeper understanding of chemical bonds and their breakage dynamics and have opened and established the field of femtochemistry (5, 6). The aim is not only to study the light−matter interaction, but to use the obtained understanding of the processes to control the dynamics in complex molecules and, in the future, even to be able to control chemical reactions (7-10). Shaping the amplitude and phase of femtosecond laser pulses has been used, for example, to control the shape of wavefunctions in atomic systems (11) or to control and optimize the single-photon and multiphoton fluorescence in atoms such as cesium (12) and complex systems, e.g....

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Section: Numerical Model and Discussionmentioning

confidence: 99%

Signatures and control of strong-field dynamics in a complex system

Meyer

Liu

Müller

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…[23,24] From a scientific point of view the REMPI nature of the process can be used to explore the nuclear and electron dynamics of the intermediate resonance in the future with the help of coherent control techniques. [25] Within that context femtosecond time-resolved photoelectron spectroscopy [26,27] has been used to study nuclear dynamics [26,28] as well as changes in the electronic structure [29] on electronically excited molecular states. Direct control of charge oscillations for molecular excitation [30] as well as the generation and detection of atomic ring currents [31] has been demonstrated.…”

Section: Introductionmentioning

confidence: 99%

Photoelectron Circular Dichroism of Bicyclic Ketones from Multiphoton Ionization with Femtosecond Laser Pulses

et al. 2014

Self Cite

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Photoelectron circular dichroism (PECD) is a CD effect up to the ten-percent regime and shows contributions from higher-order Legendre polynomials when multiphoton ionization is compared to single-photon ionization. We give a full account of our experimental methodology for measuring the multiphoton PECD and derive quantitative measures that we apply on camphor, fenchone and norcamphor. Different modulations and amplitudes of the contributing Legendre polynomials are observed despite the similarity in chemical structure. In addition, we study PECD for elliptically polarized light employing tomographic reconstruction methods. Intensity studies reveal dissociative ionization as the origin of the observed PECD effect, whereas ionization of the intermediate resonance is dominating the signal. As a perspective, we suggest to make use of our tomographic data as an experimental basis for a complete photoionization experiment and give a prospect of PECD as an analytic tool.

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“…The last two decades have seen a significant expansion of the boundaries of quantum optimal control experiments (OCEs) due to technological advances in experimental resources, especially femtosecond lasers and pulse-shaping capabilities [1][2][3][4][5][6][7][8][9][10][11][12]. OCEs have been successfully performed for a wide range of goals, including the control of molecular vibrational [13][14][15][16][17][18][19][20] and electronic states [21][22][23][24][25][26][27][28][29], the generation and coherent manipulation of X-rays [30][31][32][33][34], the control of decoherence processes [35,36], the selective cleavage and formation of chemical bonds [37][38][39][40][41][42][43], the manipulation of energy flow in macromolecular complexes [44][45][46]…”

Section: Introductionmentioning

confidence: 99%

Searching for an optimal control in the presence of saddles on the quantum-mechanical observable landscape

Riviello

Sun

et al. 2017

Phys. Rev. A

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The broad success of theoretical and experimental quantum optimal control is intimately connected to the topology of the underlying control landscape. For several common quantum control goals, including the maximization of an observable expectation value, the landscape has been shown to lack local optima if three assumptions are satisfied: (i) the quantum system is controllable, (ii) the Jacobian of the map from the control field to the evolution operator is full-rank, and (iii) the control field is not constrained. In the case of the observable objective, this favorable analysis shows that the associated landscape also contains saddles, i.e., critical points that are not local suboptimal extrema. In this paper, we investigate whether the presence of these saddles affects the trajectories of gradient-based searches for an optimal control. We show through simulations that both the detailed topology of the control landscape and the parameters of the system Hamiltonian influence whether the searches are attracted to a saddle. For some circumstances with a special initial state and target observable, optimizations may approach a saddle very closely, reducing the efficiency of the gradient algorithm. Encounters with such attractive saddles are found to be quite rare. Neither the presence of a large number of saddles on the control landscape nor a large number of system states increase the likelihood that a search will closely approach a saddle. Even for applications that encounter a saddle, well-designed gradient searches with carefully chosen algorithmic parameters will readily locate optimal controls.

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Ultrafast laser control of electron dynamics in atoms, molecules and solids

Cited by 74 publications

References 117 publications

Signatures and control of strong-field dynamics in a complex system

Signatures and control of strong-field dynamics in a complex system

Photoelectron Circular Dichroism of Bicyclic Ketones from Multiphoton Ionization with Femtosecond Laser Pulses

Searching for an optimal control in the presence of saddles on the quantum-mechanical observable landscape

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