The dynamically assisted pair creation (Schwinger effect) is considered for the superposition of two periodic electric fields acting in a finite time interval. We find a strong enhancement by orders ...of magnitude caused by a weak field with a frequency being a multitude of the strong-field frequency. The strong low-frequency field leads to shell structures which are lifted by the weaker high-frequency field. The resonance type amplification refers to a new, monotonously increasing mode, often hidden in some strong oscillatory transient background, which disappears during the smoothly switching off the background fields, thus leaving a pronounced residual shell structure in phase space.
We investigate a nonlinear response of the physical vacuum by the example of the third harmonic in radiation of the electron–positron–photon plasma excited by a strong time dependent electric field ...at the focus spot of counterpropagating laser pulses. The investigation was developed within the framework of the Bogoliubov–Born–Green–Kirkwood–Yvon kinetic theory nonperturbatively describing vacuum creation of the quasiparticle electron–positron plasma (EPP) and different channels of its interaction with the photon subsystem in the single-photon approximation that are opened in the presence of a strong semiclassical field. We investigate the radiation of EPP in the annihilation channel on the basis of the well known approximations and compare the obtained result with the semiclassical radiation of the plasma oscillations. In the high-frequency range for large adiabaticity parameter the quantum radiation dominates in comparison with the semiclassical one.
We present a detailed analysis of the self-consistent system of kinetic equations (KEs) describing electron-positron pair production from vacuum under the action of a spatially homogeneous ...time-dependent electric field of arbitrary polarization. The physical significance of all the basic functions of the kinetic theory is ascertained. It is demonstrated that the total system of the KEs consists of two coupled quasiparticle and spin subsystems with their integrals of motion. A projection method is proposed in order to obtain the KE system in two particular cases: linearly polarized external electric field and (2+1)-dimensional description of quasiparticles in graphene. We also address the energy conservation law taking into account the internal plasma field and describe an alternative rigorous derivation of the KE system.
Pair production and optical lasers Blaschke, D B; Prozorkevich, A V; Roberts, C D ...
Physical review letters,
04/2006, Letnik:
96, Številka:
14
Journal Article
Recenzirano
Odprti dostop
Electron-positron pair creation in a standing wave is explored using a parameter-free quantum kinetic equation. Field strengths and frequencies corresponding to modern optical lasers induce a ...material polarization of the QED vacuum, which may be characterized as a plasma of e+e- quasiparticle pairs with a density of approximately 10(20) cm-3. The plasma vanishes almost completely when the laser field is zero, leaving a very small residual pair density n(r) which is the true manifestation of vacuum decay. The average pair density per period is proportional to the laser intensity but independent of the frequency nu. The density of residual pairs also grows with laser intensity but n(r) proportional to nu(2). With optical lasers at the forefront of the current generation, these dynamical QED vacuum effects can plausibly generate 5-10 observable two-photon annihilation events per laser pulse.
We develop a self-consistent kinetic description of a
e
+
e
–
γ
plasma, generated from vacuum in a focal spot of counterpropagating laser pulses. Our model assumes purely time-dependent external ...(laser) field, but properly takes into account the semiclassical internal (plasma) field, as well as quantum radiation. While nonperturbative kinetic description of
e
+
e
–
-pair production from vacuum and the simplest variant of backreaction problem have been previously addressed, quantum radiation is included in such a model for the first time. To achieve this goal we derived coupled kinetic equations for the electron, positron, and photon plasma species and the Maxwell equation for the internal electric field. Photon subsystem is included systematically using the BBGKY chain, which we truncate at the second order of perturbation theory by taking into account the annihilation and radiation channels. An important application of our results would be consideration of laser field depletion due to cascade production beyond the locally constant field approximation.
Counter-propagating and suitably polarized light (laser) beams can provide conditions for pair production. Here, we consider in more detail the following two situations: (i) in the homogeneity ...regions of anti-nodes of linearly polarized ultra-high intensity laser beams, the Schwinger process is dynamically assisted by a second high-frequency field, e.g. by an XFEL beam; and (ii) a high-energy probe photon beam colliding with a superposition of co-propagating intense laser and XFEL beams gives rise to the laser-assisted Breit–Wheeler process. The prospects of such bi-frequent field constellations with respect to the feasibility of conversion of light into matter are discussed.
In the framework of strong field QED, the generation of a residual alternating polarization current is demonstrated, which remains after switching off an external field pulse. This effect is ...stipulated by inertial properties of the physical vacuum. In the standard vacuum D = 2+1 QED, this current is rapidly damped fast but can be available, apparently, for observation in the graphene, where the Fermi velocity vF ≪ c plays an analogous role as the light velocity.
BBGKY Method in Strong Field QED Smolyansky, S. A.; Fedotov, A. M.; Dmitriev, V. V.
Physics of particles and nuclei,
07/2020, Letnik:
51, Številka:
4
Journal Article
Recenzirano
Electron-positron plasma can be naturally produced by a massive self-sustained cascade seeded by particles injected or created spontaneously from vacuum under the action of a strong laser field. We ...consider a quantum kinetic equation for such a plasma and simplification of the collision integral for photon emission along the polarization direction of the field.
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