Light-matter interactions at extreme intensities: boiling the quantum vacuum at SLAC and beyond

At the so-called critical or Schwinger intensity the quantum vacuum becomes unstable with respect to electron-positron pair production. This strong-field regime of quantum electrodynamics (QED) plays an important role in extreme astrophysical plasmas, in upcoming laboratory high-energy density laser-plasma experiments, and at the interaction point of future high-luminosity lepton colliders. At SLAC's FACET-II the Lorentz boost of 10GeV electrons will be exploited to reach the QED critical field in the electron rest frame.

This experiment facilitates the first observation of strong-field vacuum breakdown and related phenomena. In the foreseeable future electromagnetic fields far beyond the QED critical one will become achievable, allowing us to study light-matter interactions in a regime where all existing theoretical calculations break down and qualitatively novel phenomena are conjectured to occur.