Speaker
Description
Nonlinear Compton scattering (NCS), the merging of multiple photons into one photon through collision with an energetic electron, is a fundamental process in strong-field quantum electrodynamics (SFQED). The degree of nonlinearity in NCS is quantified by the quantum nonlinearity parameter $\chi$,[1] defined as the electromagnetic field strength observed by the electron in its rest frame relative to the intrinsic field strength of QED, $E_S=1.3\times 10^{18} ~ \mathrm{V/m}$. In this regard, the condition $\chi=1$ serves as a critical milestone marking the transition from the weakly (perturbatively) nonlinear regime to the strongly (non-perturbatively) nonlinear regime. Consequently, the experimental realization of $\chi=1$ has been intensely pursued in the ultra-intense laser community to recreate such extreme physical conditions in the laboratory.
In this talk, we present recent experimental results obtained under the conditions $\chi=0.46$ [2] and $\chi=1.4$ at the Center for Relativistic Laser Science (CoReLS), reporting a definitive entry into the strongly nonlinear regime. In addition to the detailed analysis of these experimental results, we will discuss the broader implications of such laser-based SFQED research to high-energy astrophysics.
[1] V. I. Ritus, “Quantum effects of the interaction of elementary particles with an intense electromagnetic field,” Journal of Soviet Laser Research 6, 497 (1985).
[2] M. Mirzaie et al., “All-optical nonlinear Compton scattering performed with a multi-petawatt laser,” Nature Photonics 18, 1212 (2024).