Seminar given by Xavier Sarazin from the IJClab

Seminar given by Xavier Sarazin from the IJClab (Laboratoire Irène Joliot Curie Physique des 2 Infinis, Université Paris-Saclay, CNRS), on Thursday 13 April 2023 at 1.15pm in the Auditorium of the Institut d'Optique in Palaiseau, on the topic: "The DeLLight experiment to observe the optical nonlinearity in vacuum with intense laser pulses."

Abstract: "Quantum electrodynamics (QED) predicts that the vacuum should be a non-linear optical medium: the speed of light in the vacuum should decrease when the vacuum is subjected to intense electromagnetic fields. This amazing property of vacuum has never been observed before.
The DeLLight (Deflection of Light by Light) experiment seeks to measure this effect using ultra-intense femtosecond laser pulses delivered by the LASERIX platform (E =2.5J, 30fs, 10Hz) of the IJCLab laboratory (Université Paris-Saclay). The innovative method of DeLLight is to measure by interferometry the refraction of a low energy laser pulse (probe), induced by the index gradient of the vacuum produced by a high intensity external pulse (pump). The refraction of the probe pulse is detected by a Sagnac interferometer.
In this seminar, I will start by explaining the scientific motivation for studying the optical index of vacuum and the few existing experimental tests. I will then describe the experimental method and the technical challenges of the DeLLight project. Finally, I will present the recent results of the DeLLight measurements in a low-energy gas obtained with the pilot experiment, results that validate the experimental method."