Cécile Robilliard

The BMV experiment : a novel apparatus to study the propagation of light in a transverse magnetic field

Abstract.In this paper, we describe in detail the BMV (Biréfringence Magnétique du Vide) experiment, a novel apparatus to study the propagation of light in a transverse magnetic field. It is based on a very high finesse Fabry-Perot cavity and on pulsed magnets specially designed for this purpose. We justify our technical choices and we present the current status and perspectives.

Polarization state of the optical near field

The polarization state of the optical electromagnetic field lying several nanometers above complex dielectric-air interfaces reveals the intricate light-matter interaction that occurs in the near-field zone. From the experimental point of view, access to this information is not direct and can only be extracted from an analysis of the polarization state of the detected light. These polarization states can be calculated by different numerical methods, well suited to near-field optics. In this paper, we apply two different techniques (localized Greens function method and differential theory of gratings) to separate each polarization component associated with both electric and magnetic optical near fields produced by nanometer sized objects. A simple dipolar model is used to get an insight into the physical origin of the near-field polarization state. In a second stage, accurate numerical simulations of field maps complete data produced by analytical models. We conclude this study by demonstrating the role played by the near-field polarization in the formation of the local density of states.

Observing Quantum Vacuum Lensing in a Neutron Star Binary System

In this Letter we study the propagation of light in the neighborhood of magnetized neutron stars. Because of the optical properties of quantum vacuum in the presence of a magnetic field, the light emitted by background astronomical objects is deviated, giving rise to a phenomenon of the same kind as the gravitational one. We give a quantitative estimation of this effect, and we discuss the possibility of its observation. We show that this effect could be detected by monitoring the evolution of the recently discovered double neutron star system J0737-3039.

Magnetoelectric directional nonreciprocity in gas-phase molecular nitrogen.

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 2η‖ exp(N2) = (4.7± 1)× 10 m.V.T for λ = 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 ∆n = (5± 2) × 10, which makes its observation in quantum vacuum a conceivable challenge.

Wave functions, relative phase and interference for atomic Bose-Einstein condensates

Abstract In this article, we present a tutorial discussion of the coherence properties of Bose–Einstein condensates. We use a formalism which is similar to the one used in quantum optics. We describe within the variational approximation the question of the relative phase of two condensates. To evaluate the structure factors of a condensate, we briefly review the Bogolubov approach and describe light scattering off a condensate using the linear response formalism. Finally, we study the effect of atomic interactions on the condensates dynamics.

Matter Neutrality Test Using a Mach-Zehnder Interferometer

Neutrality of atoms and neutrons is already well established, with upper limits on the residual charge close to 10-21|qe| where qe is the electron charge. The present paper proves that the sensitivity of atom interferometry is sufficient to compete with these previous measurements, with the additional advantage of dealing with single isolated particles. An experiment involving a three grating Mach-Zehnder atom interferometer using Bragg diffraction on laser standing waves and a slow lithium atomic beam is discussed with some details. Its sensitivity and the systematic effects due to atomic polarisability are evaluated carefully.

The BMV project: Search for photon oscillations into massive particles

In this contribution to PSAS08 we report on the research activities developed in our Toulouse group, in the framework of the BMV project, concerning the search for photon oscillations into massive particles, such as axion-like particles in the presence of a strong transverse magnetic field. We recall our main result obtained in collaboration with LULI at Ecole Polytechnique (Palaiseau, France). We also present the very preliminary results obtained with the BMV experiment which is set up at LNCMP (Toulouse, France).

Atom interferometry: Principles and applications to fundamental physics

The first part of this contribution presents an overview of atom interferometry. In a second part, we discuss in greater details the sensitivity of such experiments to weak perturbations and their application to direct test of the electric neutrality of atoms with extreme precision.

Some theoretical and experimental aspects of three-grating Mach–Zehnder atom interferometers

In this contribution, we present some recent theoretical results concerning the fringe contrast in Mach–Zehnder atom interferometers and the use of Bloch states to describe atomic diffraction. We also describe the observation of diffraction of lithium at thermal energy by a quasi-resonant laser standing wave.Abstract In this contribution, we present some recent theoretical results concerning the fringe contrast in Mach–Zehnder atom interferometers and the use of Bloch states to describe atomic diffraction. We also describe the observation of diffraction of lithium at thermal energy by a quasi-resonant laser standing wave.