Plasma physics in strong laser fields

Plasma behavior in extremely strong background electromagnetic fields is substantially modified from that of classical plasma owing to the onset of relativistic quantum electrodynamics (QED) processes. These processes include the stochastic emission of photons by electrons and the decay of a photon into an electron-positron pair. They are important because electron kinetic behavior is affected by momentum loss during the emission of energetic photons (known as "radiation reaction"), and plasma density may continuously vary over time through pair production. Such plasma behavior may be observed in extreme astrophysical environments and in focused laser light at the highest intensities. The coupling of quantum emission processes and relativistic collective particle dynamics results in dramatically new plasma physics phenomena, such as the generation of dense electron-positron pair plasma from near vacuum, complete laser energy absorption through QED processes, modified plasma dispersion properties, and anomalous particle trapping phenomena. This talk will review the fundamental physics of QED in strong fields and address open questions, provide an overview of pioneering experiments conducted in the laboratory, discuss theoretical and computational advances aimed at understanding plasma in strong fields, and explore upcoming and future research involving ultra-high-intensity lasers and high-energy beam facilities worldwide.