Optimization of high-order harmonic generation by optimal control theory: Ascending a functional landscape in extreme conditions

Schaefer, Ido; Kosloff, Ronnie

doi:10.1103/physreva.101.023407

Cited by 4 publications

(2 citation statements)

References 68 publications

(136 reference statements)

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“…To reduce the sensitivity to the noises, the high-frequency components in h is reduced by penalizing the energy of high-order derivatives [30], which is given by…”

Section: Related Workmentioning

confidence: 99%

A Spline Kernel-Based Approach for Nonlinear System Identification with Dimensionality Reduction

Zhang

Zhu

2020

Electronics

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This paper proposes a novel approach for identification of nonlinear systems. By transforming the data space into a feature space, kernel methods can be used for modeling nonlinear systems. The spline kernel is adopted to produce a Hilbert space. However, a problem exists as the spline kernel-based identification method cannot deal with data with high dimensions well, resulting in huge computational cost and slow estimation speed. Additionally, owing to the large number of parameters to be estimated, the amount of training data required for accurate identification must be large enough to satisfy the persistence of excitation conditions. To solve the problem, a dimensionality reduction strategy is proposed. Transformation of coordinates is made with the tool of differential geometry. The purpose of the transformation is that no intersection of information with relevance to the output will exist between different new states, while the states with no impact on the output are extracted, which are then abandoned when constructing the model. Then, the dimension of the kernel-based model is reduced, and the number of parameters to be estimated is also reduced. Finally, the proposed identification approach was validated by simulations performed on experimental data from wind tunnel tests. The identification result turns out to be accurate and effective with lower dimensions.

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“…To reduce the sensitivity to the noises, the high-frequency components in h is reduced by penalizing the energy of high-order derivatives [30], which is given by…”

Section: Related Workmentioning

confidence: 99%

A Spline Kernel-Based Approach for Nonlinear System Identification with Dimensionality Reduction

Zhang

Zhu

2020

Electronics

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“…[30][31][32][33][34][35][36][37][38] While there is an extensive amount of work on controlling laser-matter interactions via selected field parameters such as carrier envelope phase or polarization, so far the application of full control theory to strong-field science and to double ionization in particular has been limited. Some selected applications to date include control of single ionization, 34,[39][40][41] and experimental pulse optimization for double ionization with IR pulses. 37 The objective of this article is twofold.…”

Section: Introductionmentioning

confidence: 99%

Control of concerted back-to-back double ionization dynamics in helium

Larsson

Tannor

2021

The Journal of Chemical Physics

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Double ionization (DI) is a fundamental process that despite its apparent simplicity provides rich opportunities for probing and controlling the electronic motion. Even for the simplest multielectron atom, helium, new DI mechanisms are still being found. To first order in the field strength, a strong, external field doubly-ionizes the electrons in helium such that they are ejected into the same direction (front-to-back motion). The ejection into opposite directions (back-to-back motion) cannot be described to first order, making it a challenging target for control. Here, we address this challenge and optimize the field with the objective of back-toback double ionization, using a (1+1)-dimensional model. The optimization is performed using four different control procedures: (1) short-time control, (2) derivative-free optimization of basis expansions of the field, (3) the Krotov method and (4) control of the classical equations of motion. All four procedures lead to fields with dominant back-to-back motion. All the fields obtained exploit essentially the same two-step mechanism leading to back-to-back motion: first, the electrons are displaced by the field into the same direction. Second, after the field turns off, the nuclear attraction and the electron-electron repulsion combine to generate the final motion into opposite directions for each electron. By performing quasi-classical calculations, we confirm that this mechanism is essentially classical.

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Reducing anomalous reflection from complex absorbing potentials: A semiclassical approach

2021

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Optimization of high-order harmonic generation by optimal control theory: Ascending a functional landscape in extreme conditions

Abstract: The ω sampling is the same as the DCT sampling (Cf. Eq. (C5)). The functional has to be expressed by the terms of the discrete optimization space:where J d is a discretized variant of J. Theǭ(ω) dependence in J is reformulated by discrete means;J energy is replaced by

Cited by 4 publications

References 68 publications

A Spline Kernel-Based Approach for Nonlinear System Identification with Dimensionality Reduction

A Spline Kernel-Based Approach for Nonlinear System Identification with Dimensionality Reduction

Control of concerted back-to-back double ionization dynamics in helium

Reducing anomalous reflection from complex absorbing potentials: A semiclassical approach

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