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Biréfringence Magnétique du Vide (BMV)

The BMV project (Vacuum Magnetic Birefringence) is an ambitious experiment whose goal is to check in-laboratory predictions for vacuum energy in quantum electrodynamics. This theory predicts that vacuum, in the presence of a magnetic field, behaves as a birefringent medium. The experiment blends intense pulsed magnetic fields with a sensitive optical apparatus, centered around a high-finesse cavity

Detail subject : Classical electrodynamics was modified in the early XXth century to take into account quantum mechanics, giving rise to quantum electrodynamics (QED) ; QED is currently the best tested theory in the world (with the measurements of the anomalous magnetic moment of the electron, the Lambshift, the Rydberg constant, the hydrogne hyperfine structure, etc...). Nevertheless, there exist phenomena predicted by this theory which yet eludes observation, such as the efffect of optical non-linearity of vacuum, or more specifically the birefringence of vacuum in presence of a magnetic field. Vacuum birefringence is a minute effect, rendering its experimental measurement very challenging task. thanks to recent technological improvements at LNCMI in toulouse, we are closer than ever to observing this phenomenon for the first time. The principe of our experiment is to measure the ellipticity adquired by linearly polarized light travelling through vacuum in a region of intense magnetic field. Results have already been obtained with magnetic birefringence measurements for nitrogen, argon and helium gas. A long series of magnetic pulses have been performed for vacuum. These first results show that the BMV experiment has one of the best sensitivities in the world. a new set-up is already employing a novel coil technology and couples with a new high- performance optical set-up.

Publications linked to the theme Cadene, P. Berceau, M. Fouche, R. Battesti and C. Rizzo Vacuum magnetic linear birefringence using pulsed fields : status of the BMV experiment. Eur. Phys. J. D 68, 16 (2014)

M. Hartman, A. Riviere, R. Battesti and C. Rizzo Noise characterization for resonantly enhanced polarimetric vacuum magnetic-birefringence experiments Rev. Sci. Instrum. 88, 123114 (2017) ;

R. Battesti & al. High magnetic fields for fundamental physics Physics Reports 765–766 (2018) 1–39

The student will be inserted into the research group. The experiment sits in a clean room where the student will experience numerous skills during his training such as optics, ultra-high vacuum, magnetic fields, electronics, Fabry-Perot cavitiers and metrology.

This master internship could be extended into a PhD within the same research subject.