Vacuum High Harmonic Generation in the Shock Regime
When an intense laser pulse interacts with an underdense plasma, radiation can be generated at integer multiples of the laser pulse’s frequency. Such high harmonic generation is also predicted to occur when very intense laser pulses interact with the virtual electron-positron plasma of the vacuum. I will give an overview of some of the experimental scenarios that have been suggested in order to measure the elusive effect of real photon-photon scattering and will finish by presenting the results of this recent project on vacuum high harmonic generation and induced electromagnetic shock.