Seminarium Optyczne

The ongoing progress in laser technology leads to field strengths at which the vacuum becomes unstable and breaks down into electron-positron pairs, offering prospects to eventually see the Schwinger effect in the laboratory. As predicted by Breit and Wheeler in 1934, already the collision of two single energetic photons can produce a pair, yet with an extremely small probability. In contrast, photon densities achieved in focus areas of modern lasers facilitate multiphoton reaction channels, decreasing the required photon energy and leading to measurable particle yields.We present detailed calculations within the framework of laser-dressed strong-field QED. We investigate a setup in which two co-propagating laser beams collide with highly energetic gamma quanta, which allows two different interaction regimes to be examined. For low-intensity lasers with a suitably-chosen frequency ratio, interference effects between production channels of different photon-number combinations can be observed in the angular distributions of the particles and even in the total particle count rate. For a high-intensity optical laser used in an experiment to observe the Schwinger effect, we demonstrate how the addition of aow-intensity yet high-frequency laser can strongly enhance the particle yield.