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In this work, using the time-dependent density functional theory, we address the electron tunneling triggered by short (single-cycle and several-cycle) optical pulses in narrow metallic gaps under conditions relevant for actual experiments.…

Changing some of its parameters over time is a paradigmatic way of driving an otherwise isolated many-body quantum system out of equilibrium, and a vital ingredient for building quantum computers and simulators. Here, we further develop a…

Quantum Physics · Physics 2024-11-06 Lennart Dabelow , Peter Reimann

Spin-polarization of an ultrarelativistic electron beam head-on colliding with an ultraintense laser pulse is investigated in the quantum radiation-reaction regime. We develop a Monte-Carlo method to model electron radiative spin effects in…

The photoionization spectrum of an atom in a magnetic field is calculated by combining R-matrix propagation with local adiabatic basis expansions. This approach considerably increases the speed and the energy range over which calculations…

Atomic Physics · Physics 2009-11-13 F. Mota-Furtado , P. F. O'Mahony

The exact factorization of the time-dependent electron-nuclear wavefunction has been employed successfully in the field of quantum molecular dynamics simulations for interpreting and simulating light-induced ultrafast processes. In this…

Chemical Physics · Physics 2021-09-29 Federica Agostini , E. K. U. Gross

We derive a multiconfigurational time-dependent Hartree theory for systems with particle conversion. In such systems particles of one kind can convert to another kind and the total number of particles varies in time. The theory thus extends…

Quantum Physics · Physics 2009-02-07 Ofir E. Alon , Alexej I. Streltsov , Lorenz S. Cederbaum

The ionization of two-active-electron systems by intense laser fields is investigated theoretically. In comparison with time-dependent Hartree-Fock and exact two electron simulation, we show that the ionization rate is overestimated in SAE…

Atomic Physics · Physics 2015-06-18 Zengxiu Zhao , Jianmin Yuan

We present a general theory for calculating photon transitions in arbitrarily time-varying metamaterials. This theory circumvents the difficulties of conventional approaches in solving such a general problem by exploiting the eigenstates of…

Optics · Physics 2024-10-27 Artuur Stevens , Christophe Caloz

We investigate the strong-field ionization of atomic hydrogen in a few-cycle elliptically polarized infrared pulse by solving the time-dependent Schr\"odinger equation. The dependence of the photoelectron momentum distribution on the pulse…

Atomic Physics · Physics 2022-11-30 Nicolas Douguet , Klaus Bartschat

A general {\it ab-initio} and non-perturbative method to solve the time-dependent Schr\"odinger equation (TDSE) for the interaction of a strong attosecond laser pulse with a general atom, i.e., beyond the models of quasi-one-electron or…

Atomic Physics · Physics 2016-11-17 X. Guan , O. Zatsarinny , K. Bartschat , B. I. Schneider , J. Feist , C. J. Noble

Time-dependent density functional theory is implemented in an all electron solid-state code for the case of fully non-collinear spins. We use this to study laser induced demagnetization in Fe, Co and Ni. It is shown that this…

Materials Science · Physics 2014-06-26 K. Krieger , J. K. Dewhurst , P. Elliott , S. Sharma , E. K. U. Gross

In the presence of a (time-dependent) macroscopic electric field the electron dynamics of dielectrics cannot be described by the time-dependent density only. We present a real-time formalism that has the density and the macroscopic…

Materials Science · Physics 2016-07-27 M. Grüning , D. Sangalli , C. Attaccalite

Theoretical approaches to the photoionization of few-electron atoms are discussed. These include nonequilibrium Greens functions and wave function based approaches. In particular, the Multiconfiguration Time-Dependent Hartree-Fock method is…

Atomic Physics · Physics 2015-05-14 M. Bonitz , D. Hochstuhl , S. Bauch , K. Balzer

We present a detailed study of the ionisation probability of H and H$_{2}^{+}$ induced by a short intense laser pulse. Starting from a Coulomb-Volkov description of the process we derive a multipole-like expansion where each term is…

Atomic Physics · Physics 2013-07-11 Renata Della Picca , Juan Fiol , Pablo Daniel Fainstein

Time-dependent quantities are calculated in the linear response limit for a correlated one dimensional model atom driven by an external quadrupolar time-dependent field. Besides the analysis of the time-evolving energy change in the…

Quantum Physics · Physics 2015-01-29 I. Nagy , I. Aldazabal , M. L. Glasser

We formulate the problem of a two-level system in a linearly polarized laser field in terms of a nonlinear Riccati-type differential equation and solve the equation analytically in time intervals much shorter than half the optical period.…

Quantum Physics · Physics 2007-05-23 R. Parzynski , M. Sobczak , A. Plucinska

The effect of autoionizing resonances in atomic systems and processes is reviewed. Theoretical framework for treating resonances in the coupled channel approximation using the R-matrix method, as well as approximations related to plasma…

High Energy Astrophysical Phenomena · Physics 2024-05-16 Anil Pradhan

The ultimate control of magnetic states of matter at femtosecond (or even faster) timescales defines one of the most pursued paradigm shifts for future information technology. In this context, ultrafast laser pulses developed into extremely…

Mesoscale and Nanoscale Physics · Physics 2022-03-15 Hanan Hamamera , Filipe Souza Mendes Guimarães , Manuel dos Santos Dias , Samir Lounis

New features of molecular wires can be observed when they are irradiated by laser fields. These effects can be achieved by periodically oscillating fields but also by short laser pulses. The theoretical foundation used for these…

Mesoscale and Nanoscale Physics · Physics 2007-05-23 Sven Welack , Michael Schreiber , Ulrich Kleinekathoefer

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