Missions

The Postdoctoral Research Associate will join the UPX research group at Laboratoire d'Optique Appliquée (LOA), a CNRS laboratory, to work on the topic of plasma-based acceleration, extreme beams and strong-field QED, in the context of the ANR (French national research funding agency) g4QED project (“Gamma photon sources as a path for strong-field QED experiments”). The primary goal of this postdoctoral position is to implement and conduct experiments aimed at advancing strong-field QED experiments based on plasma accelerators and extreme particle beams, as well as to develop high-brightness high-energy photon light sources that can be generated in these experiments, in particular from nonlinear inverse Compton scattering and from extreme beam-multifoil collisions (eg in the E-332 experiment at SLAC). The project will include the development of advanced measurements and detectors for these challenging experiments, and will be complemented by numerical and theoretical studies when appropriate. The work will be performed in collaboration with other major labs and the experiments will take place at LOA using in-house laser systems and at international facilities such as the FACET-II 10 GeV accelerator at SLAC in the US and multi-PW to 10 PW laser facilities such as APOLLON in France and ELI-NP in Romania.

Activities

The scientific context of the position is related to plasma accelerators, extreme beams and strong-field QED.

Scientific Context:
State-of-the-art multi-PW lasers, such as APOLLON (France) and ELI-NP (Romania), and km-scale accelerators such as FACET-II at Stanford (USA) [1], allow to create on Earth the extreme conditions required to test fundamental interactions between particles and strong fields. Such interactions follow the laws of strong-field quantum electrodynamics (QED) that has emerged as a promising discovery science area with exciting opportunities. Strong-field QED effects appear when the electric field experienced by the electron in its rest frame approaches the Schwinger field , and their most spectacular manifestations include the production of electron-positron pairs through the inverse-Compton scattering and the nonlinear Breit-Wheeler processes. At multi-PW laser facilities such as APOLLON and ELI-NP, strong-field QED experiments can be performed by colliding high-energy electrons produced by a novel type of particle accelerator, namely a laser-driven plasma accelerator, with a high-intensity counterpropagating laser pulse or another source of strong fields. In addition to the use of an auxiliary laser pulse to generate the strong fields, our team is exploring two promising concepts: (i) the use of a plasma mirror to reflect the laser pulse and enable the collision between the high-energy electrons and the laser pulse [2-4], and (ii) the use of multiple foils to focus the electron beam to very small size, and use the focused electron beam itself as the source of strong fields [5,6], a focusing concept that we have recently demonstrated in the E-332 experiment at SLAC with the FACET-II 10 GeV accelerator facility.

[1] V. Yakimenko et al., Phys. Rev. Accel. Beams 22, 101301 (2019).
[2] K. Ta Phuoc et al., Nature Photonics 6, 308 (2012).
[3] A. Matheron et al., arXiv:2412.19337 (2024).
[4] A. Matheron et al., Phys. Rev. Research 7, L032011 (2025).
[5] A. Sampath et al., Phys. Rev. Lett. 126, 064801 (2021).
[6] A. Matheron et al., Comm. Phys. 6, 141 (2023).

Skills

- PhD in physics
- Research record demonstrating a strong potential for research
- Highly motivated young researcher
- Human qualities to work effectively within a team and coordinate the research with students, postdocs and technicians.
- Experience in either laser and optical physics, particle beam physics, strong-field QED or plasma physics is recommended.

Work Context

The start date of the position is flexible, typically between spring and fall 2026, with a 2-year position. Salary determined according to the experience of the candidate (gross salary between 3131,32€ and 4526,02€ per month depending on experience). The job comes with health, pension and unemployment benefits. The postdoctoral researcher will be working with Prof. Sébastien CORDE in the UPX group at LOA.

Constraints and risks

No specific constraints.