11 research outputs found
Ultra-strong laser pulses: streak-camera for gamma-rays via pair production and quantum radiative reaction
We show that a strong laser pulse combined with a strong x-ray pulse can be
employed in a detection scheme for characterizing high-energy -ray
pulses down to the zeptosecond timescale. The scheme employs streak imaging
technique built upon the high-energy process of electron-positron pair
production in vacuum through the collision of a test pulse with intense laser
pulses. The role of quantum radiation reaction in multiphoton Compton
scattering process and limitations imposed by it on the detection scheme are
examined
Strong signature of one-loop self-energy in polarization resolved nonlinear Compton scattering
The polarization dynamics of electrons including multiple nonlinear Compton
scattering during the interaction of a circularly-polarized ultraintense laser
pulse with a counterpropagating ultrarelativistic electron beam is
investigated. While electron polarization emerges mostly due to spin-flips at
photon emissions, there is a non-radiative contribution to the polarization
which stems from the one-loop QED radiative corrections to the self-energy,
which admits of a simple physical model. We put forward a method to single out
the non-radiative contribution to the polarization, employing the reflection
regime of the interaction when the radiation reaction is significant. The
polarization of electrons that penetrate in the forward direction through a
colliding laser is shown to be dominated by the loop effect, while the
reflected electrons are mostly polarized by spin-flips at photon emissions. We
confirm this effect by quantum Monte Carlo simulations considering the helicity
transfer from the laser field to the electrons, taking into account the
opposite sign of the polarizations induced by the non-radiative loop effect and
radiative spin-flip. Our Monte Carlo simulations show a polarization signal as
high as from the non-radiative effect, amenable for experimental
detection with current technology
Strong signatures of radiation reaction below the radiation dominated regime
The influence of radiation reaction (RR) on multiphoton Thomson scattering by
an electron colliding head-on with a strong laser beam is investigated in a new
regime, in which the momentum transferred on average to the electron by the
laser pulse approximately compensates the one initially prepared. This
equilibrium is shown to be far more sensitive to the influence of RR than
previously studied scenarios. As a consequence RR can be experimentally
investigated with currently available laser systems and the underlying widely
discussed theoretical equations become testable for the first time.Comment: 4 pages, 3 figure
Light diffraction by a strong standing electromagnetic wave
The nonlinear quantum interaction of a linearly polarized x-ray probe beam
with a focused intense standing laser wave is studied theoretically. Because of
the tight focusing of the standing laser pulse, diffraction effects arise for
the probe beam as opposed to the corresponding plane wave scenario. A
quantitative estimate for realistic experimental conditions of the ellipticity
and the rotation of the main polarization plane acquired by the x-ray probe
after the interaction shows that the implementation of such vacuum effects is
feasible with future X-ray Free Electron Laser light.Comment: 5 pages, 2 figures. Published versio
Non-perturbative vacuum-polarization effects in proton-laser collisions
In the collision of a high-energy proton beam and a strong laser field,
merging of the laser photons can occur due to the polarization of vacuum. The
probability of photon merging is calculated by accounting exactly for the laser
field and presents a highly non-perturbative dependence on the laser intensity
and frequency. It is shown that the non-perturbative vacuum-polarization
effects can be experimentally measured by combining the next-generation of
table-top petawatt lasers with presently available proton accelerators.Comment: 5 pages, 2 figure
Enhancement of vacuum polarization effects in a plasma
The dispersive effects of vacuum polarization on the propagation of a strong
circularly polarized electromagnetic wave through a cold collisional plasma are
studied analytically. It is found that, due to the singular dielectric features
of the plasma, the vacuum effects on the wave propagation in a plasma are
qualitatively different and much larger than those in pure vacuum in the regime
when the frequency of the propagating wave approaches the plasma frequency. A
possible experimental setup to detect these effects in plasma is described.Comment: 33 pages, 3 figure
Laser photon merging in proton-laser collisions
The quantum electrodynamical vacuum polarization effects arising in the
collision of a high-energy proton beam and a strong, linearly polarized laser
field are investigated. The probability that laser photons merge into one
photon by interacting with the proton`s electromagnetic field is calculated
taking into account the laser field exactly. Asymptotics of the probability are
then derived according to different experimental setups suitable for detecting
perturbative and nonperturbative vacuum polarization effects. The
experimentally most feasible setup involves the use of a strong optical laser
field. It is shown that in this case measurements of the polarization of the
outgoing photon and and of its angular distribution provide promising tools to
detect these effects for the first time.Comment: 38 pages, 9 figure
Large orders in strong-field QED
We address the issue of large-order expansions in strong-field QED. Our
approach is based on the one-loop effective action encoded in the associated
photon polarisation tensor. We concentrate on the simple case of crossed fields
aiming at possible applications of high-power lasers to measure vacuum
birefringence. A simple next-to-leading order derivative expansion reveals that
the indices of refraction increase with frequency. This signals normal
dispersion in the small-frequency regime where the derivative expansion makes
sense. To gain information beyond that regime we determine the factorial growth
of the derivative expansion coefficients evaluating the first 80 orders by
means of computer algebra. From this we can infer a nonperturbative imaginary
part for the indices of refraction indicating absorption (pair production) as
soon as energy and intensity become (super)critical. These results compare
favourably with an analytic evaluation of the polarisation tensor asymptotics.
Kramers-Kronig relations finally allow for a nonperturbative definition of the
real parts as well and show that absorption goes hand in hand with anomalous
dispersion for sufficiently large frequencies and fields.Comment: 26 pages, 6 figure
Extremely high-intensity laser interactions with fundamental quantum systems
The field of laser-matter interaction traditionally deals with the response
of atoms, molecules and plasmas to an external light wave. However, the recent
sustained technological progress is opening up the possibility of employing
intense laser radiation to trigger or substantially influence physical
processes beyond atomic-physics energy scales. Available optical laser
intensities exceeding 10^{22}\;\text{W/cm^2} can push the fundamental
light-electron interaction to the extreme limit where radiation-reaction
effects dominate the electron dynamics, can shed light on the structure of the
quantum vacuum, and can trigger the creation of particles like electrons, muons
and pions and their corresponding antiparticles. Also, novel sources of intense
coherent high-energy photons and laser-based particle colliders can pave the
way to nuclear quantum optics and may even allow for potential discovery of new
particles beyond the Standard Model. These are the main topics of the present
article, which is devoted to a review of recent investigations on high-energy
processes within the realm of relativistic quantum dynamics, quantum
electrodynamics, nuclear and particle physics, occurring in extremely intense
laser fields.Comment: 58 pages, 26 figures, version accepted by Reviews of Modern Physic