All-optical quantum vacuum signals in two-beam collisions

We study the collision of two optical laser pulses in a pump-probe setup using beams with circular and elliptic cross section and estimate the number of discernible signal photons induced by quantum vacuum nonlinearities. In this analysis we study strategies to optimize the quantum vacuum signal discernible from the background of the driving lasers. One of the main results is that the collision of two maximally focused lasers does not lead to the best discernible signal. Instead, widening the focus typically improves the signal to background separation in the far field. For petawatt class lasers, an optimal choice of the focus waist yields several discernible photons per shot in contrast to no discernible signal for tight focusing. Further enhancement is possible by using an elliptical waist.

Automated summary

This study investigates the collision of two optical laser pulses in a pump-probe setup and estimates the discernible signal photons induced by quantum vacuum nonlinearities. Optimizing the focus and using an elliptical waist can improve the separation of signal and background, resulting in an increased number of discernible photons.