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We introduce a \textit{non-modal} analysis technique that characterizes the diffusion properties of spectral element methods for linear convection-diffusion systems. While strictly speaking only valid for linear problems, the analysis is…

Computational Physics · Physics 2019-01-30 Pablo Fernandez , Rodrigo Moura , Gianmarco Mengaldo , Jaime Peraire

When the dynamical data of a system only convey dynamic information over a limited operating range, the identification of models with good performance over a wider operating range is very unlikely. Nevertheless, models with such…

Systems and Control · Electrical Eng. & Systems 2020-09-07 Leandro Freitas , Bruno H. G. Barbosa , Luis A. Aguirre

Controlling the longitudinal phase space of high-brightness relativistic electron beams is crucial for advancing a broad spectrum of charged-particle-based instrumentation and scientific frontiers. A generalized method for achieving this…

A high-performance shooting algorithm is developed to compute time-periodic solutions of the free-surface Euler equations with spectral accuracy in double and quadruple precision. The method is used to study resonance and its effect on…

Fluid Dynamics · Physics 2015-06-11 Jon Wilkening , Jia Yu

Here we report the development of SPRAY, a massively parallel GPU accelerated, smoothed particle hydrodynamics (SPH)-based, radiation hydrodynamics (RHD) code designed specifically for simulating high intensity laser-plasma interactions.…

Computational Physics · Physics 2026-04-23 Min Ki Jung , Hakhyeon Kim , Su-San Park , Eung Soo Kim , Yong-Su Na , Sang June Hahn

Spectral methods, thanks to the high accuracy and the possibility of using fast algorithms, represent an effective way to approximate collisional kinetic equations in kinetic theory. On the other hand, the loss of some local invariants can…

Numerical Analysis · Mathematics 2021-05-28 Lorenzo Pareschi , Thomas Rey

The atomistic resolution recently achieved by ultrafast spectroscopies demands corresponding theoretical advances. Real-time time-dependent density-functional theory (RT-TDDFT) with Ehrenfest dynamics offers an optimal trade-off between…

Materials Science · Physics 2022-10-19 Jannis Krumland , Matheus Jacobs , Caterina Cocchi

Sequence modeling faces challenges in capturing long-range dependencies across diverse tasks. Recent linear and transformer-based forecasters have shown superior performance in time series forecasting. However, they are constrained by their…

Machine Learning · Computer Science 2024-11-25 Bong Gyun Kang , Dongjun Lee , HyunGi Kim , DoHyun Chung , Sungroh Yoon

In this paper, we present a novel stochastic and spatially lumped multi-mode model to describe the nonlinear dynamics of actively Q-switched lasers and random perturbations due to amplified spontaneous emission. This model will serve as a…

We describe a generalized algorithm for evaluating the steady-state solution of the density matrix equation of motion, for the pump-probe scheme, when two fields oscillating at different frequencies couple the same set of atomic transitions…

Quantum Physics · Physics 2024-01-31 Zifan Zhou , Yael Sternfeld , Jacob Scheuer , Selim M. Shahriar

This work is concerned with optical imaging in strongly diffusive environments. We consider a typical setting in optical coherence tomography where a sample is probed by a collection of wavefields produced by a laser and propagating through…

Optics · Physics 2024-12-10 Randy Bartels , Olivier Pinaud , Maxine Varughese

Based on the work done by an electromagnetic field on an atomic or molecular electronic system, a general gauge invariant formulation of transient absorption spectroscopy is presented within the semi-classical approximation. Avoiding…

Accurate and efficient fluid flow models are essential for applications relating to many physical phenomena including geophysical, aerodynamic, and biological systems. While these flows may exhibit rich and multiscale dynamics, in many…

Fluid Dynamics · Physics 2024-08-27 Benjamin D. Shaffer , Jeremy R. Vorenberg , M. Ani Hsieh

Nonlinear spectroscopy employs a series of laser pulses to interrogate dynamics in large interacting many-body systems, and has become a highly successful method for experiments in chemical physics. Current quantum optical experiments…

Quantum Physics · Physics 2016-10-19 Frank Schlawin , Manuel Gessner , Shaul Mukamel , Andreas Buchleitner

Ultrafast characterization and control of many-body interactions and elementary excitations are critical to understanding and manipulating emergent phenomena in strongly correlated systems. In particular, spin interaction plays an important…

Strongly Correlated Electrons · Physics 2018-12-06 Yao Wang , Thomas P. Devereaux , Cheng-Chien Chen

Using the density matrix formalism, we prove an existence theorem of the periodic steady-state for an arbitrary periodically-driven system. This state has the same period as the modulated external influence, and it is realized as an…

Atomic Physics · Physics 2016-02-17 V. I. Yudin , A. V. Taichenachev , M. Yu. Basalaev , D. Kovalenko

Entropy-based inference methods have gained traction for improving the reliability of Large Language Models (LLMs). However, many existing approaches, such as entropy minimization techniques, suffer from high computational overhead and fail…

Machine Learning · Computer Science 2026-01-27 Jin Li , Zhebo Wang , Tianliang Lu , Mohan Li , Wenpeng Xing , Meng Han

Passively mode-locked semiconductor disk lasers have received tremendous attention from both science and industry. Their relatively inexpensive production combined with excellent pulse performance and great emission wavelength flexibility…

Optics · Physics 2024-02-22 Stefan Meinecke , Kathy Lüdge

Precise spectral control in the hard X-ray regime remains a long-standing challenge that limits applications in atomic-scale science and ultrafast spectroscopy. We present an actively mode-locked cavity-based X-ray free-electron laser that…

Accelerator Physics · Physics 2025-10-02 Nanshun Huang , Hanxiang Yang , Haixiao Deng

Diffusing Alpha-emitters Radiation Therapy (DaRT) is a new method for treating solid tumors using alpha particles. Unlike conventional radiotherapy, where the physical models for dose calculations are known and routinely used, for DaRT a…

Medical Physics · Physics 2021-11-09 Guy Heger , Lior Arazi