Experimental Observation of Optical Rotation Generated in Vacuum by a Magnetic Field

Abstract

We report the experimental observation of a light polarization rotation in vacuum in the presence of a transverse magnetic field. Assuming that data distribution is Gaussian, the average measured rotation is $(3.9\ifmmode\pm\else\textpm\fi{}0.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}12}\text{ }\text{ }\mathrm{rad}/\mathrm{\text{pass}}$, at 5 T with 44 000 passes through a 1 m long magnet, with $\ensuremath{\lambda}=1064\text{ }\text{ }\mathrm{nm}$. The relevance of this result in terms of the existence of a light, neutral, spin-zero particle is discussed.