Observation of magneto-electric non-reciprocity in molecular nitrogen gas

Abstract

We report the direct observation of the non-reciprocity of the velocity of light, induced in a gas by electric and magnetic fields. This bilinear magneto-electro-optical phenomenon appears in the presence of crossed electric and magnetic fields perpendicular to the light wavevector, as a refractive index difference between two counterpropagating directions. Using a high finesse ring cavity, we have measured this magneto-electric non-reciprocity in molecular Nitrogen at ambient temperature and atmospheric pressure; for light polarized parallel to the magnetic field it is $2{\eta }_{\parallel \exp }({\mathrm{N}}_2)=(4.7\pm 1)\times 10^{-23}{m.V}^{-1}{.T}^{-1}$ for $\lambda =1064$nm, in agreement with the expected order of magnitude. Our measurement opens the way to a deeper insight into light-matter interaction, since bilinear magneto-electric effects correspond to a coupling beyond the electric dipole approximation. We were able to measure a magneto-electric non-reciprocity as small as $\Delta n=(5\pm 2)\times 10^{-18}$, which makes its observation in quantum vacuum a conceivable challenge.

4 pages, accepted for publication in Physical Review Letters

References in corpus (2)

• Measurement of the Cotton-Mouton effect in nitrogen, oxygen, carbon dioxide, argon, and krypton with the Q & A apparatus
• Towards a first observation of magneto-electric directional anisotropy and linear birefringence in gases

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