  All-optical experiments at the high-intensity frontier offer a promising
route to unprecedented precision tests of quantum electrodynamics in strong
macroscopic electromagnetic fields. So far, most theoretical studies of
all-optical signatures of quantum vacuum nonlinearity are based on simplifying
approximations of the beam profiles and pulse shapes of the driving laser
fields. Since precision tests require accurate quantitative theoretical
predictions, we introduce an efficient numerical tool facilitating the
quantitative theoretical study of all-optical signatures of quantum vacuum
nonlinearity in generic laser fields. Our approach is based on the vacuum
emission picture, and makes use of the fact that the dynamics of the driving
laser fields are to an excellent approximation governed by classical Maxwell
theory in vacuum. In combination with a Maxwell solver, which self-consistently
propagates any given laser field configuration, this allows for accurate
theoretical predictions of photonic signatures of vacuum nonlinearity in
high-intensity laser experiments from first principles. We employ our method to
simulate photonic signatures of quantum vacuum nonlinearity in laser pulse
collisions involving a few-cycle pulse, and show that the angular and spectral
distributions of the emitted signal photons deviate from those of the driving
laser beams.
