No Arabic abstract
The properties of the forced oscillations of electron-positron plasma (EPP) generated from vacuum under the action of a short laser pulse are considered. Calculating the density of the conduction and polarization currents within the quantum kinetic approach, we demonstrate the presence of plasma oscillations at the frequency of the external field and its odd harmonics. It is expected that radiation generated by these plasma oscillations can be observed outside the interaction region, for example, outside the focal spot of two counterpropagating laser beams, and can serve as an indicator of the Schwinger mechanism of the EPP creation from vacuum.
The concept of ponderomotive potential is upgraded to a regime in which radiation friction becomes dominant. The radiation friction manifests itself in novel features of long-term capturing of the particles released at the focus and impenetrability of the focus from the exterior. We apply time scales separation to the Landau-Lifshitz equation splitting the particle motion into quivering and slow drift of a guiding center. The drift equation is deduced by averaging over fast motion.
We consider the possibility of experimental verification of vacuum e^+e^- pair creation at the focus of two counter-propagating optical laser beams with intensities 10^{20}-10^{22} W/cm^2, achievable with present-day petawatt lasers, and approaching the Schwinger limit: 10^{29} W/cm^2 to be reached at ELI. Our approach is based on the collisionless kinetic equation for the evolution of the e^+ and e^- distribution functions governed by a non-Markovian source term for pair production. As possible experimental signals of vacuum pair production we consider e^+e^- annihilation into gamma-pairs and the refraction of a high-frequency probe laser beam by the produced e^+e^- plasma. We discuss the dependence of the dynamical pair production process on laser wavelength, with special emphasis on applications in the X-ray domain (X-FEL), as well as the prospects for mu^+mu^- and pi^+pi^- pair creation at high-intensity lasers. We investigate perspectives for using high-intensity lasers as ``boosters of ion beams in the few-GeV per nucleon range, which is relevant, e.g., to the exploration of the QCD phase transition in laboratory experiments.
A collective, macroscopic signature to detect radiation friction in laser-plasma experiments is proposed. In the interaction of superintense circularly polarized laser pulses with high density targets, the effective dissipation due to radiative losses allows the absorption of electromagnetic angular momentum, which in turn leads to the generation of a quasistatic axial magnetic field. This peculiar inverse Faraday effect is investigated by analytical modeling and three-dimensional simulations, showing that multi-gigagauss magnetic fields may be generated at laser intensities $>10^{23}~mbox{W cm}^{-2}$.
Using the gauge-gravity duality, we study the holographic Schwinger effect by performing the potential analysis on the confining D3- and D4-brane background with D-instantons then evaluate the pair production/decay rate by taking account into a fundamental string and a single flavor brane respectively. The two confining backgrounds with D-instantons are obtained from the black D(-1)-D3 and D0-D4 solution with a double Wick rotation. The total potential and pair production/decay rate in the Schwinger effect are calculated numerically by examining the NG action of a fundamental string and the DBI action of a single flavor brane all in the presence of an electric field. In both backgrounds our numerical calculation agrees with the critical electric field evaluated from the DBI action and shows the potential barrier is increased by the presence of the D-instantons, thus the production/decay rate is suppressed by the D-instantons. Our interpretation is that particles in the dual field theory could acquire an effective mass through the Chern-Simons interaction or the theta term due to the presence of D-instantons so that the pair production/decay rate in Schwinger effect is suppressed since it behaves as $e^{-m^{2}}$. Our conclusion is in agreement with the previous results obtained in the deconfined D(-1)-D3 background at zero temperature limit and from the approach of the flavor brane in the D0-D4 background. In this sense, this work may be also remarkable to study the phase transition in Maxwell-Chern-Simons theory and observable effects by the theta angle in QCD.
We propose a realization of two remarkable effects of Dicke physics in quantum simulation of light-matter many-body interactions with artificial quantum systems. These effects are a superradiant decay of an ensemble of qubits and the opposite radiation trapping effect. We show that both phenomena coexist in the crossover regime of a moderately bad single-mode cavity coupled to the qubit subsystem. Depending on the type of the initial state and on the presence of multipartite entanglement in it, the dynamical features can be opposite resulting either in the superradiance or in the radiation trapping despite of the fact that the initial state contains the same number of excited qubits. The difference originates from the symmetrical or nonsymmetrical character of the initial wave function of the ensemble, which corresponds to indistinguishable or distinguishable emitters. We argue that a coexistence of both effects can be used in dynamical quantum simulators to demonstrate realization of Dicke physics, effects of multipartite quantum entanglement, as well as quantum interference and thus to deeply probe quantum nature of these artificial quantum systems.