Non linear electrodynamic effects in vacuum have been predicted since the earliest days of Quantum Electrodynamics (QED) with the formulation of the Euler effective Lagrangian in 1935. Among these effects there is vacuum magnetic birefringence, which is still lacking a direct laboratory observation. Experiments that want to measure this effect use high sensitivity polarimeters. Key ingredients of the polarimeter are a long optical path within an intense magnetic field and a time dependent effect. To lengthen the optical path a Fabry-Perot interferometer is generally used. Interestingly, there is a difficulty in reaching the predicted shot noise limit of such polarimeters. The VMB@CERN proposal overcomes the intrinsic mirror noise difficulty by using a spare LHC superconducting magnet at CERN together with a novel polarisation modulation scheme for the polarimeter. The present research addressed the need to implement a wave front sensing system for active alignment of the mirrors of the cavity, coupled to a stabilization loop for the suppression of pointing noise of the input beam to the cavity.

Giuseppe Messineo – INFN FERRARA

Giuseppe Messineo (Ph.D. in Physics, University of Trieste 2011) is a Fellini fellow at INFN Ferrara working on the project “Alignment and Pointing noise suppression for the VMB@CERN experiment”. His main research interest is designing and performing precision experiments and tests of Fundamental Physics. He has been involved in axion-like particle searches and in experiments to study vacuum magnetic birefringence, the Casimir effect and particle generation from quantum fields subject to time-dependent boundaries.

He has a strong background in optics, in particular in the field of high finesse optical cavities, laser frequency stabilization and polarimetry.