Magnetic vacuum birefringence
Description
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 hydrogen hyperfine structure, etc.). Nevertheless, there exist phenomena predicted by this theory which yet eludes observation, such as the effect 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. The principle of our experiment is to measure the ellipticity acquired by linearly polarized light travelling through vacuum in a region of intense magnetic field.
A new set-up is ready employing a novel coil technology and coupled with a new high-performance optical set up.
Research staff
Techniques
Fabry Perot cavity of very high fineness (F= 530,000), length = 2.5m
Transverse pulsed magnetic field: Bmax=11 T; B^2Lmax= 100 T^2m
Birefringence measurements in gases
Birefringence measurements of mirror layers
Publications
Collaboration (NDA) :
Advanced Materials Laboratory / SAFRAN: Study of the birefringence of high-reflectivity mirror layers
Selected publications
1- J. Agil, R. Battesti, and C. Rizzo, Monte Carlo study of the BMV vacuum linear magnetic birefringence experiment, The European Physical Journal D 75, 90 (2021)
2– J. Béard, J. Agil, R. Battesti, and C. Rizzo, A novel pulsed magnet for magnetic linear birefringence measurements, Review of Scientific Instruments, 92, 104710 (2021)
3- J. Agil, R. Battesti, and C. Rizzo, Vacuum birefringence experiments : optical noise, The European Physical Journal D 76, 10 (2022)
4- J. Agil, R. Battesti, C. Rizzo, On the speed of light in a vacuum in the presence of a magnetic field, Eur. Phys. J. H 48, 2, (2023).
5- J. Agil, B. Letourneur, S. George, R. Battesti, C. Rizzo, Characterisation of the waveplate associated to layers in interferential mirrors, Eur. Phys. J. Applied Physics 98, 61 (2023) .
6- N. Gutierrez et al, Optical characterization of high performance mirrors based on cavity ringdown time measurements with 6 degrees of freedom mirror positioning, Rev. of Sc. Instruments 94, 10 (2023)
7- J. Agil, R. Battesti, C. Rizzo, D. Bakalov, On the positronium g-factor, The European Physical Journal D 77, 196 (2023)
LNCMI publications on HAL