Battements de photons uniques dans un interféromètre à base de modulateurs acousto-optiques

International audienceWe present in the following a quantum optics experiment appropriate for advanced undergraduate students with former experience in quantum optics. It extends classical single photon setups to the time dependent domain. We demonstrate self-heterodyning of heralded single photons using a Mach-Zender like interferometer where beamsplitters are replaced by two acousto-optic modulators (AOMs). The single pho-ton beat note is recorded over time at the frequency difference between the RF generators driving the AOMs, which makes it observable directly on a human time scale i. e. with periods above a fraction of a second. To compare with our observations, we tailor the standard quantum optics formalism for beam splitters to take into account the frequency shifts associated with the AOMs

Guided atom laser: transverse mode quality and longitudinal momentum distribution

We analyze the outcoupling of a matter wave into a guide by a time-dependent spilling of the atoms from an initially trapped Bose-Einstein condensate. This process yields intrinsically a breakdown of the adiabatic condition that triggers the outcoupling of the wave function. Our analysis of the time-dependent engineering and manipulation of condensates in momentum space in this context enables to work out the limits due to interactions in the mode quality of a guided atom laser. This study is consistent with recent experimental observations of low transverse excitations of guided atom lasers and suggests (i) an optimal strategy to realize such quasi-monomode guided atom lasers with, in addition, the lowest possible longitudinal velocity dispersion, or alternatively (ii) a strategy for engineering the atomic flux of the atom laser.Comment: Phys. Rev. A 84, 043618 (2011

Negative experimental evidence for magneto-orbital dichroism - supplemental information

A light beam can carry both spin angular momentum (SAM) and orbital angular momentum (OAM). SAM is commonly evidenced by circular dichroism (CD) experiments {\em i. e.} differential absorption of left and right-handed circularly polarized light. Recent experiments, supported by theoretical work, indicate that the corresponding effect with OAM instead of SAM is not observed in chiral matter. Isotropic materials can show CD when subjected to a magnetic field (MCD). In Ref. ~\onlinecite{Mathevet2012} we report a set of experiments, under well defined conditions, searching for magnetic orbital dichroism (MOD), differential absorption of light as a function of the sign of its OAM. We experimentally demonstrate that this effect, if any, is smaller than a few $10^{-4}$ of MCD for the Nd:YAG $^4I_{9/2}\rightarrow^4F_{5/2}$ transition. This transition is essentially of electric dipole nature. We give an intuitive argument suggesting that the lowest order of light matter interaction leading to MOD is the electric quadrupole term. We give here more experimental details and extra measurements.Comment: 6 pages, 7 figures. Supplemental material for a publication in Optics Expres

Polarization state of the optical near-field

The polarization state of the optical electromagnetic field lying several nanometers above complex dielectric structures reveals the intricate light-matter interaction that occurs in this near-field zone. This information can only be extracted from an analysis of the polarization state of the detected light in the near-field. 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 Green Function Method and Differential Theory of Gratings) to separate each polarisation component associated with both electric and magnetic optical near-fields produced by nanometer sized objects. The analysis is carried out in two stages: in the first stage, we use a simple dipolar model to achieve insight into the physical origin of the near-field polarization state. In the second stage, we calculate accurate numerical field maps, simulating experimental near-field light detection, to supplement the 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.Comment: 9 pages, 11 figures, accepted for publication in Phys. Rev.

Approche expérimentale de l'équation de diffusion

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Magnetic circular dichroism as a local probe of the polarization ofa focused Gaussian beam

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Fizeau et l’entraÎnement partiel de l’éther

Entre 1849 et 1851, Hippolyte Fizeau a réalisé successivement trois expériences fondamentales relatives à la vitesse de la lumière. Ce sont toutes trois de véritables tours de force expérimentaux qui ont eu des conséquences majeures dans l’évolution de nos conceptions de la lumière et, comme l’a attesté Albert Einstein lui-même, dans l’avènement de la relativité restreinte. Nous présentons à la fois le contexte et les conséquences historiques ainsi que la réplique moderne que nous avons réalisée de l’expérience de 1851 dite « d’entraînement partiel de l’éther »