Quantum vacuum nonlinearity allows for the effect of laser photon merging in the collision of two (or more) laser beams. As the merged photons origin from a manifestly inelastic process, their energy differs significantly from the background photons of the driving lasers, making them accessible for experiments. However, the number of merged photons is typically considered to be very small.
First strong field experiments at the JETI super laser in Jena are reported.
In August 2020, a first experimental campaign was conducted to investigate light scattered from a single laser focus in vacuum. Any photons measured constitute an undesired background signal for an actual multi-beam collision experiment. Key findings will be presented and possible improvements as well as the expected scaling towards higher power collision experiments will be discussed.