High Harmonic Generation in cavity for an attosecond quantum source
Attophysics is at the forefront of time-resolved spectroscopy. Indeed, it harnesses the shortest light pulse probe that can be produced experimentally, thanks to the high harmonic generation (HHG) process. A standard way to trigger HHG is to submit an atomic system to an oscillating electromagnetic field whose strength compares with the Coulomb potential bounding electrons with their nuclei. This non-linear, non-perturbative optical effect produces a broadband coherent radiation in the extreme ultraviolet (XUV) frequency range, which forms attosecond pulses (1e-18 s). Since its discovery in the late 1980s, continuous experimental and theoretical efforts have been dedicated to get a complete understanding of this complex phenomenon. Despite the tremendous success of attosecond science, there is still no consensus about a quantum description of the process. We foresee that such a description of HHG would push forward our understanding of non-linear optics and open up new perspectives for attosecond science.
Relativistic laboratory astrophysics
This PhD project is concerned with the numerical and theoretical modeling of the ultra-relativistic plasmas encountered in a variety of astrophysical environments such as gamma-ray bursts or pulsar wind nebulae, as well as in future laboratory experiments on extreme laser-plasma, beam-plasma or gamma-plasma interactions. The latter experiments are envisioned at the multi-petawatt laser facilities currently under development worldwide (e.g. the European ELI project), or at next-generation high-energy particle accelerators (e.g. the SLAC/FACET-II facility).
The plasma systems under scrutiny have in common a strong coupling between energetic particles, photons and quantum electrodynamic effects. They will be simulated numerically using a particle-in-cell (PIC) code developed at CEA/DAM over the past years. Besides the collective effects characteristic of plasmas, this code describes a number of gamma-ray photon emission and electron-positron pair creation processes. The purpose of this PhD project is to treat additional photon-particle and photon-photon interaction processes, and then to examine thoroughly their impact and interplay in various experimental and astrophysical configurations.