A nonperturbative theory is developed for free-free transitions of electrons colliding with atoms in intense high-frequency laser fields. The energy the incoming assumed to be smaller than that photons. Rather simple expressions are derived multiphoton absorption amplitudes. Large deviations from laser-free case shown appear elastic scattering. applies at already existing frequencies but extends beyond, extreme ultraviolet range.

In this review we summarize our progress in the investigation of fundamental processes quantum electrodynamics laser fields relativistic power view more recent experimental generation field intensities, yielding ponderomotive energy shifts Up order magnitude mc2 and beyond. particular, electron–positron pairs during collision pulses with ions or protons appears to become feasible.

Energy-angular distributions of electron-positron pair creation in collisions a laser beam and nonlaser photon are calculated using the $S$-matrix formalism. The field is modeled as finite pulse, similar to formulation introduced our recent paper context Compton scattering [Phys. Rev. A 85, 062102 (2012)]. nonperturbative regime considered here. energy spectra created particles compared with corresponding obtained modulated plane-wave approximation for driving field. very good agreement...

Generation of high harmonics by the interaction intense laser fields with periodic crystal structures is investigated theoretically. A nonperturbative Floquet-Bloch theory interacting system (crystal plus field) developed and applied to obtain field-modified band structure system. The mean energy spectrum, dispersion fluctuation in photon space, associated standard deviation spectral entropy are calculated. harmonic generation spectra a thin crystal, for neodymium-doped yttrium aluminum...

The spectra of Compton radiation emitted during electron scattering off an intense laser beam are calculated using the framework strong-field quantum electrodynamics. We model these beams as finite length plane-wave-fronted pulses, similar to Neville and Rohrlich [Phys. Rev. D 3, 1692 (1971)], or trains such pulses. Expressions for energy angular distributions photons derived that a comparison both situations becomes meaningful. Comparing frequency isolated pulse train, we find very good...

Electron-ion radiative recombination in the presence of a bicircular laser pulse is analyzed beyond dipole approximation. A consists two counter-rotating circularly polarized pulses with commensurate carrier frequencies. It demonstrated that broad bandwidth radiation can be generated process and its spectrum significantly enhanced by tailoring field. special emphasis put on analyzing temporal properties radiation.

Electron–ion radiative recombination in the presence of a bicircular laser pulse is analyzed beyond dipole approximation. A consists two counter-rotating circularly polarized pulses with commensurate carrier frequencies. It demonstrated that broad bandwidth radiation can be generated process and its spectrum significantly enhanced by tailoring field. special emphasis put on analyzing temporal properties radiation.

Multiphoton above-threshold ionization (ATI) is considered for hydrogen in the framework of Keldysh-Faisal-Reiss (KFR) models but treating Coulomb effects residual ions on ionized electrons more completely than previous work. The spectrum ATI peaks evaluated linearly polarized laser light, and it shown that with appropriate inclusion interaction hot are predicted by original KFR theories. Moreover, angular distributions to have sidelobes. \textcopyright{} 1996 American Physical Society.

Production of electron-positron pairs in the collision a high-energy photon with high-intensity few-cycle laser pulse is studied. By utilizing frameworks laser-dressed spinor and scalar quantum electrodynamics, comparison between production Dirac Klein-Gordon particles drawn. Positron energy spectra angular distributions are presented for various parameters. We identify conditions under which predictions from theory either closely resemble or largely differ those proper theory. In...

Generation of electron vortices in photodetachment ${\mathrm{H}}^{\ensuremath{-}}$ by circularly polarized laser pulses is analyzed means strong-field approximation and numerically solving the time-dependent Schr\"odinger equation. A very good agreement shown for magnitude phase probability amplitude from both approaches. We demonstrate that spiral-like patterns detachment, observed a pair counter-rotating pulses, cannot be associated with nonvanishing topological charge vortices. The latter...

We reconsider nonlinear Compton scattering, induced by a linearly polarized laser field. The radiation power is assumed to be in the relativistic regime such that ponderomotive energy of an electron field order magnitude electron's rest or even above it, i.e., ${U}_{p}>~{\mathrm{mc}}^{2}.$ investigate detail for several scattering configurations angular dependences processes N absorbed photons $\ensuremath{\omega},$ assuming general beam and can cross at arbitrary angle.

Production of electron-positron pairs from vacuum in the combined electromagnetic fields a high-intensity laser pulse and an atomic nucleus is studied within framework laser-dressed quantum electrodynamics. The focus lies on influence exerted by finite length energy spectra created electrons positrons, which examined broad range field frequencies intensities. results for isolated short are also compared with corresponding calculations infinite train pulses. It shown that its carrier-envelope...

Nonlinear Thomson and Compton processes, in which energetic electrons collide with an intense optical pulse, are investigated the framework of classical quantum electrodynamics. Spectral modulations emitted radiation, appearing as either oscillatory or pulsating structures, observed explained. It is shown that both processes generate a bandwidth radiation spanning range few MeV, occurs small cone along propagation direction colliding electrons. Most importantly, these broad structures...

Abstract The nonlinear Compton scattering by a linearly polarized laser pulse of finite duration is analyzed, with focus on the spin effects target electrons. We show that, although accompanied electron no-spin flip dominant, for some energy regions photons their emission dominated process leading to flip. This feature observed different durations, and can be treated as signature quantum behavior. Similar conclusions are reached when analyzing scattered spectra. time, sensitivity...

The Compton and Thomson radiation spectra generated in collisions of an electron beam with a powerful laser are studied the framework quantum classical electrodynamics, respectively. We show that there frequency regimes where both nearly identical, which for scattering relates to process preserves spin. Although corresponding probability amplitudes exhibit different global phases. This has pronounced consequences, we demonstrate by investigating temporal power distributions cases. that,...

We consider the process of electron-ion recombination in a powerful laser field and investigate spectrum emitted x-ray radiation. This is interest interaction radiation with gaseous or solid targets connection harmonic coherent production. The treated framework inverse Keldysh-Faisal-Reiss model describing ingoing electron either by Gordon-Volkov wave Coulomb-Volkov solution. Even for higher energies impinging electrons, considerable Coulomb effects are recognized. evaluate rates generated...

We give a Floquet analysis of photoemission electrons and high-order harmonic generation from solid surface interacting with intense laser fields. A general theoretical algorithm, within three-dimensional quasi-free-electron model, is presented. It takes account the effective masses electron both outside solid, as well treating reflected refracted The steady-state photocurrent obtained diagonal photon components expectation value time-dependent current operator surface, while off-diagonal...

Presently available laser sources can yield powers for which the ponderomotive energy ${U}_{p}$ of an electron be equal to or even larger than rest ${\mathrm{mc}}^{2}$ electron. Therefore it has become interest consider fundamental radiation-induced assisted processes in such powerful fields. In present work we laser-assisted electron-electron scattering a field, assuming that beam linear polarization. We investigate detail angular and polarization dependence differential cross sections...

Triply differential probability rates for electron-positron pair creation in laser-nucleus collisions, calculated within the $S$-matrix approach, are investigated as functions of nuclear recoil. Pronounced enhancements multiphoton production found a nonzero momentum transfer from colliding nucleus. The corresponding show very dramatic dependence on polarization laser field impinging nucleus; only linearly polarized light considerably large. We focus therefore this case. Our numerical results...

Probability rates of electron-positron pair creation in collisions a relativistic nucleus with two-color laser field are calculated using the $S$-matrix approach. The case when both components have commensurate frequencies and comparable strengths is considered. Pronounced interference effects observed angular distributions created particles as well total probability production. These show significant phase dependence pair-creation process.

Electron-positron-pair creation in collisions of a modulated laser pulse with high-energy photon (nonlinear Breit-Wheeler process) is studied by means strong-field quantum electrodynamics. It shown that the driving modulations lead to appearance comb structures energy spectra produced positrons (electrons). demonstrated these combs result from coherent enhancement probability amplitudes pair different pulse, thus resembling Young-type double-slit experiment for antimatter (matter) waves.

The formation of quantum vortices in photodetachment by a sequence left- and right-handed circularly polarized laser pulses various configurations is analyzed using either the strong-field approximation or numerical solution time-dependent Schr\"odinger equation. Two types pulse sequences are considered: reducible irreducible. While former can be decomposed into series consecutive identical (irreducible) subtrains pulses, latter cannot that way. As we show, vortex pattern probability...

In view of recently achieved extreme laser powers for which the ponderomotive energy ${U}_{p}\ensuremath{\gg}2m{c}^{2}$, it has become interest to reconsider fundamental processes quantum electrodynamics in such powerful fields. present work, we evaluate rates producing electron-positron pairs by impact pulses power on highly charged ions at rest. Contrary previous investigations, shall consider a linearly polarized pulse, since contribution ${A}^{2}$ part electromagnetic interaction becomes...