IP-Paris Best Thesis Award in physics for Aimé Matheron

His research focused on accessing the strong-field regime of quantum electro-dynamics (QED), where close to the so–called Schwinger field, an electric field of ~10¹⁸ V/m), the quantum vacuum becomes unstable. His thesis introduced two experimental schemes for approaching the Schwinger field in the rest frame of ultra-relativistic electrons colliding with ultra-intense electro-magnetic fields:

In experiments at the SLAC National Accelerator Laboratory, he identified a new focusing mechanism for electron beams propagating through thin aluminum foils. At each interface, the reflection of the beam’s own electromagnetic fields induces a focusing force, achieving beam densities far beyond conventional magnetic optics. Such ultra-dense beams can reach the strong-field QED regime through their own fields.

In experiments at the French petawatt laser facility APOLLON, the laser both accelerated electrons via laser-plasma acceleration and collided with them after reflection on a foil, reaching up to 15% of the Schwinger field in the electrons’ rest frame. Simulations support that with a simple upgrade, adding a second gas jet in which the laser self-focuses just before collision, the Schwinger threshold could be exceeded.

Strong-field QED, long considered purely theoretical, is now becoming experimentally accessible thanks to petawatt-class laser systems and their interactions with plasmas. This research is emerging as one of the major fundamental applications of laser-plasma acceleration methods developed at LOA.