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Based on numerical solutions of the time-dependent Schr\"odinger equation for either one or two active electrons, we propose a method for observing instantaneous level shifts in an oscillating strong infrared (IR) field in time, using a…

Atomic Physics · Physics 2015-05-28 Feng He , Camilo Ruiz , Andreas Becker , Uwe Thumm

In this paper we develop a framework for moment-based adaptive time integration of deterministic multifrequency thermal radiation transpot (TRT). We generalize our recent semi-implicit-explicit (IMEX) integration framework for gray TRT to…

Numerical Analysis · Mathematics 2026-02-11 Ben S. Southworth , Steven Walton , Steven B. Roberts , HyeongKae Park

Three variants of mean field methods for atomic and nuclear reactions are compared with respect to both conception and applicability: The time--dependent Hartree--Fock method solves the equation of motion for a Hermitian density operator as…

Nuclear Theory · Physics 2009-10-31 J. Uhlig , J. C. Lemm , A. Weiguny

Many questions in physical cosmology regarding the thermal and ionization history of the intergalactic medium are now successfully studied with the help of cosmological hydrodynamical simulations. Here we present a numerical method that…

Astrophysics · Physics 2009-10-31 Tom Abel , Michael L. Norman , Piero Madau

Most of the physical information about astrophysical objects is obtained via the analysis of their electromagnetic spectra. Observed data coupled with radiation transfer models in physical conditions representative of stars, planets,…

Solar and Stellar Astrophysics · Physics 2026-05-29 Maria Bergemann , Richard Hoppe

While new light sources allow for unprecedented resolution in experiments with X-rays, a theoretical understanding of the scattering cross-section is lacking. In the particular case of strongly correlated electron systems, numerical…

Strongly Correlated Electrons · Physics 2023-05-29 Krissia Zawadzki , Alberto Nocera , Adrian E. Feiguin

This study concerns the fast and accurate solution of multilevel non-LTE radiation transfer problems. We propose and evaluate an alternative iterative scheme to the classical MALI method. Our study is indeed based on the application of…

Instrumentation and Methods for Astrophysics · Physics 2015-05-20 S. Nicolas , L. Bigarré , F. Paletou

We present a new numerical approach that is able to solve the multi-dimensional radiative transfer equations in all opacity regimes on a Lagrangian, unstructured network of characteristics based on a stochastic point process. Our method…

Astrophysics · Physics 2007-05-23 Jelle Ritzerveld , Vincent Icke , Erik-Jan Rijkhorst

We describe in detail how attosecond delays in laser-assisted photoionization can be computed using perturbation theory based on two-photon matrix elements. Special emphasis is laid on above-threshold ionization, where the electron…

Atomic Physics · Physics 2015-06-19 J. M. Dahlström , E. Lindroth

Intriguing collective spontaneous cascade emissions have recently been realized. In despite of much success, a depth understanding of the complexity is still lacking. With this motivation, a new simple cascade superradiance model is…

Quantum Physics · Physics 2022-10-19 Gombojav O. Ariunbold

This work studies time-dependent electromagnetic scattering from obstacles whose interaction with the wave is fully determined by a nonlinear boundary condition. In particular, the boundary condition studied in this work enforces a power…

Numerical Analysis · Mathematics 2023-10-30 Jörg Nick

Radiative transfer and radiation hydrodynamics use the relativistic Boltzmann equation to describe the kinetics of photons. It is difficult to solve the six-dimensional time-dependent transfer equation unless the problem is highly symmetric…

Instrumentation and Methods for Astrophysics · Physics 2011-02-09 Chi-kwan Chan

The new statistical approach for calculation of radiation processes with heavy multielectron ions in plasma is developed. The method consists in consideration of atomic structure as a condensed medium, characterized by the spectrum of…

The time-dependent Maxwell system describing electromagnetic wave propagation in inhomogeneous isotropic media in the one-dimensional case reduces to a Vekua-type equation for bicomplex-valued functions of a hyperbolic variable (see…

Analysis of PDEs · Mathematics 2016-05-23 Kira V. Khmelnytskaya , Vladislav V. Kravchenko , Sergii M. Torba

The electromagnetic transition of two-level atomic systems in a waveguide is calculated. Compared with the result in free space, the spontaneous emission rate decrease because the phase space is smaller, and meanwhile, some resonance…

Quantum Physics · Physics 2009-11-07 Wu-Sheng Dai , Mi Xie

To study the temperature in a gas subjected to electromagnetic radiations, one may use the Radiative Transfer equations coupled with the Navier-Stokes equations. The problem has 7 dimensions; however with minimal simplifications it is…

Numerical Analysis · Mathematics 2023-01-25 Francois Golse , Frederic Hecht , Olivier Pironneau , Pierre-Henri Tournier , Didier Smets

We study the radiation reaction acting on an accelerating charge moving in noncommutative spacetime and obtain an expression for it. Radiation reaction, due to a nonrelativistic point charge, is found to receive a small noncommutative…

Classical Physics · Physics 2022-03-02 V. Veera Reddy , Sashideep Gutti , Asrarul Haque

Radiative transfer equation in plane parallel geometry and Kompaneets equation is solved simultaneously to obtain theoretical spectrum of 1-125 KeV photon energy range. Diffuse radiation field is calculated using time-independent radiative…

Solar and Stellar Astrophysics · Physics 2015-05-20 A. Peraiah , M. Srinivasa Rao , B. A. varghese

We derive a quantum master equation for an atom coupled to a heat bath represented by a charged particle many-body environment. In Born-Markov approximation, the influence of the plasma environment on the reduced system is described by the…

Atomic Physics · Physics 2016-05-04 Chengliang Lin , Christian Gocke , Gerd Röpke , Heidi Reinholz

The radiative transport equation accurately describes light transport in participating media such as biological tissues, though analytic solutions are known only for simple geometries. We present a pseudospectral technique to efficiently…

Computational Physics · Physics 2019-03-19 Samuel Powell , Ben T. Cox , Simon R. Arridge