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Machine learning algorithms often struggle to control complex real-world systems. In the case of nuclear fusion, these challenges are exacerbated, as the dynamics are notoriously complex, data is poor, hardware is subject to failures, and…

We present a classical model for high harmonic generation during the propagation of an intense laser pulse through an atomic gas. Numerical simulations of the model show excellent quantitative agreement with the corresponding quantum model…

Atomic Physics · Physics 2018-07-04 S. A. Berman , J. Dubois , C. Chandre , M. Perin , T. Uzer

High harmonic generation (HHG) in solids has emerged as a powerful spectroscopic method for resolving ultrafast electron dynamics and band structure properties across a wide range of materials. However, quantitative HHG studies require…

Optics · Physics 2025-12-16 S. Mandal , P. Kumar , Z. Pi , H. Y. Kim , M. Zhan , E. Goulielmakis

High-order harmonic generation (HHG) is a powerful tool for probing electronic structure and ultrafast dynamics in matter. Traditionally studied in atomic and molecular gases, HHG has recently been extended to condensed matter, enabling…

We present a novel spectroscopic technique for second harmonic generation (SHG) using femtosecond laser pulses at 30~kHz repetition rate, which nevertheless provides high spectral resolution limited only by the spectrometer. The potential…

High-order harmonic generation (HHG) is combined with resonant x-ray excitation of a core electron into the transient valence vacancy that is created in the course of the HHG process. To describe this setting, I develop a…

Atomic Physics · Physics 2015-10-15 Christian Buth

Electron ptychography provides new opportunities to resolve atomic structures with deep sub-angstrom spatial resolution and studying electron-beam sensitive materials with high dose efficiency. In practice, obtaining accurate ptychography…

Materials Science · Physics 2022-04-26 Michael C. Cao , Zhen Chen , Yi Jiang , Yimo Han

Tuning machine parameters of particle accelerators is a repetitive and time-consuming task that is challenging to automate. While many off-the-shelf optimization algorithms are available, in practice their use is limited because most…

Optimizing parameterized quantum circuits is a key routine in using near-term quantum devices. However, the existing algorithms for such optimization require an excessive number of quantum-measurement shots for estimating expectation values…

Quantum Physics · Physics 2022-08-04 Shiro Tamiya , Hayata Yamasaki

Bayesian Optimization using Gaussian Processes is a popular approach to deal with the optimization of expensive black-box functions. However, because of the a priori on the stationarity of the covariance matrix of classic Gaussian…

Machine Learning · Statistics 2019-05-10 Ali Hebbal , Loic Brevault , Mathieu Balesdent , El-Ghazali Talbi , Nouredine Melab

The Linac Coherent Light Source changes configurations multiple times per day, necessitating fast tuning strategies to reduce setup time for successive experiments. To this end, we employ a Bayesian approach to transport optics tuning to…

At the core of attosecond science lies the ability to generate laser pulses of sub-femtosecond duration. In tabletop devices the process relies on high-harmonic generation, where a major challenge is to obtain high yields and high cutoff…

Atomic Physics · Physics 2014-11-05 J. Solanpää , J. A. Budagosky , N. I. Shvetsov-Shilovski , A. Castro , A. Rubio , E. Räsänen

The solid-state harmonic generation (SSHG) derives from photocurrent coherence. The crystal symmetry, including point-group symmetry and time-reversal symmetry, constrains the amplitude and phase of the photocurrent, thus manipulates the…

Optics · Physics 2024-01-17 Chen Qian , Shicheng Jiang , Tong Wu , Hongming Weng , Chao Yu , Ruifeng Lu

Intrinsic to the process of high-order harmonic generation is the creation of plasma and the resulting spatiotemporal distortions of the driving laser pulse. Inside a high finesse cavity where the driver pulse and gas medium are reused,…

Atomic Physics · Physics 2015-05-28 T. K. Allison , A. Cingöz , D. C. Yost , J. Ye

Efficient frequency conversion techniques are crucial to the development of plasmonic metasurfaces for information processing and signal modulation. In principle, nanoscale electric-field confinement in nonlinear materials enables higher…

High-harmonic generation (HHG) in solids has emerged in recent years as a rapidly expanding and interdisciplinary field, attracting attention from both the condensed-matter and the atomic, molecular, and optics communities. It has exciting…

Atomic Physics · Physics 2022-02-09 Lun Yue , Mette B. Gaarde

When a laser pulse impinges on a molecule which is invariant under certain symmetry operations selection rules for harmonic generation (HG) arise. In other words: symmetry controls which channels are open for the deposition and emission of…

Atomic Physics · Physics 2009-11-07 D. Bauer , F. Ceccherini

The kinematics of a gliding flat-plate with spanwise oscillation has been optimized to enhance the power efficiency by using Bayesian optimization method, in which the portfolio allocation framework consists of a Gaussian process…

Fluid Dynamics · Physics 2021-09-10 Chunyu Wang , Zhaoyue Xu , Xinlei Zhang , Shizhao Wang

External seeded free-electron lasers (FELs) are compelling tools for generating fully coherent EUV and soft X-ray radiations. Echo-enabled harmonic generation (EEHG), the most typical representative of external seeded FELs, has witnessed a…

Accelerator Physics · Physics 2024-04-29 Xiaofan Wang , Li Zeng , Weiqing Zhang , Xueming Yang

The hybrid Stimulated Raman Scattering - Two Plasmon Decay instability had shown to play the dominant role for plasma waves excitation and energy absorption at interaction of very intense femtosecond obliquely incident $p$-polarized laser…

Plasma Physics · Physics 2021-01-04 I. Tsymbalov , D. Gorlova , A. Savel'ev