Enhancement of QED Processes Using Spatiotemporaly-Shaped Pulses

Recent developments in high-power laser physics have unlocked the possibility of prolific electron-positron pair creation in the laboratory when colliding with an ultrarelativistic electron beam. This is a valuable asset for future particle accelerators and colliders, as the outgoing relativistic beam of positrons can be achieved within a few microns in length, significantly reducing the cost associated with the experimental setup. It is also of great importance to probe the Strong Field Quantum Electrodynamics regime directly, of which few observations have been made thus far.

However, any application of such beams requires some level of control or tailoring over their characteristics. Specifically, control over the two dynamical variables a lepton has, momentum and spin, is of great importance for future applications. While separating positrons from electrons can be conventionally achieved, it requires a strong external magnetic field. Such a field causes the spin to precess further, compromising the final degree of polarization of the particles.

In this talk, I will show how electromagnetic field asymmetries control the outgoing particles. I will demonstrate how using the asymmetric vector potential of a bichromatic laser pulse can be used to achieve the separation of electrons from positrons after they leave the vicinity of the laser. Additionally, using circularly polarized harmonics, the particles can also acquire spin polarization, leading to a separated and polarized beam of positrons.