  With the rapid development of high-power petawatt class lasers worldwide,
exploring physics in the strong field QED regime will become one of the
frontiers for laser-plasma interactions research. Particle-in-cell codes,
including quantum emission processes, are powerful tools for predicting and
analyzing future experiments where the physics of relativistic plasma is
strongly affected by strong-field QED processes. The spin/polarization
dependence of these quantum processes has been of recent interest. In this
article, we perform a parametric study of the interaction of two laser pulses
with an ultrarelativistic electron beam. The first pulse is optimized to
generate high-energy photons by nonlinear Compton scattering and efficiently
decelerate the electron beam through quantum radiation reaction. The second
pulse is optimized to generate electron-positron pairs by nonlinear
Breit-Wheeler decay of the photons with the maximum polarization dependence.
This may be experimentally realized as a verification of the strong field QED
framework, including the spin/polarization rates.
