Quantum Noise in Multipixel Image Processing

We consider the general problem of the quantum noise in a multipixel measurement of an optical image. We first give a precise criterium in order to characterize intrinsic single mode and multimode light. Then, using a transverse mode decomposition, for each type of possible linear combination of the pixels' outputs we give the exact expression of the detection mode, i.e. the mode carrying the noise. We give also the only way to reduce the noise in one or several simultaneous measurements.Comment: 8 pages and 1 figur

Continuous-wave phase-sensitive parametric image amplification

We study experimentally parametric amplification in the continuous regime using a transverse-degenerate type-II Optical Parametric Oscillator operated below threshold. We demonstrate that this device is able to amplify either in the phase insensitive or phase sensitive way first a single mode beam, then a multimode image. Furthermore the total intensities of the amplified image projected on the signal and idler polarizations are shown to be correlated at the quantum level.Comment: 14 pages, 7 figures, submitted to Journal of Modern Optics, Special Issue on Quantum Imagin

Atlas des températures et des courants géostrophiques de 1979 à 1985 déduits des mesures XBT le long des rails de navigation du Pacifique tropical

Dans le Pacifique tropical, la concentration de données du réseau XBT (expendable bathythermograph) ORSTOM-SIO (Scripps Institutio of Oceanography) autour de trois rails de navigation a permis de construire des champs de températures et de courants géostrophiques. Afin d'obtenir des champs de températures les plus précis possible, le fichier original ORSTOM-SIO a été tout d'abord triplé par la récupération d'un maximum de données XBT et de quelques données hydrologiques et de sondes CTD (conductivité, température, profondeur) auprès de différents services océanographiques. Les champs de températures à trois dimensions (latitude, profondeur, temps) ont été obtenu en regroupant, indépendamment de la longitude, les données de profils thermiques autour de trois rails moyens situés dans les zones ouest, centre et est du Pacifique tropical. Ces champs s'étendent en latitude de 20°S à 20°N pour les zones ouest et centre et de 20°S à 7°N pour la zone est, en profondeur de 0 à 4OO m et en temps de janvier 1979 à décembre 198

Three-Nucleon Continuum by means of the Hyperspherical Adiabatic Method

This paper investigates the possible use of the Hyperspherical Adiabatic basis in the description of scattering states of a three-body system. In particular, we analyze a 1+2 collision process below the three-body breakup. The convergence patterns for the observables of interest are analyzed by comparison to a unitary equivalent Hyperspherical Harmonic expansion. Furthermore, we compare and discuss two different possible choices for describing the asymptotic configurations of the system, related to the use of Jacobi or hyperspherical coordinates. In order to illustrate the difficulties and advantages of the approach two simple numerical applications are shown in the case of neutron-deuteron scattering at low energies using s-wave interactions. We found that the optimization driven by the Hyperspherical Adiabatic basis is not as efficient for scattering states as in bound state applications.Comment: 29 pages, 5 figures, accepted for publication in Few-Body Systems (in press

Optimum Small Optical Beam Displacement Measurement

We derive the quantum noise limit for the optical beam displacement of a TEM00 mode. Using a multimodal analysis, we show that the conventional split detection scheme for measuring beam displacement is non-optimal with 80% efficiency. We propose a new displacement measurement scheme that is optimal for small beam displacement. This scheme utilises a homodyne detection setup that has a TEM10 mode local oscillator. We show that although the quantum noise limit to displacement measurement can be surpassed using squeezed light in appropriate spatial modes for both schemes, the TEM10 homodyning scheme out-performs split detection for all values of squeezing.Comment: 13 pages, 7 figure

Independent nonclassical tests for states and measurements in the same experiment

We show that one single experiment can test simultaneously and independently both the nonclassicality of states and measurements by the violation or fulfillment of classical bounds on the statistics. Nonideal measurements affected by imperfections can be characterized by two bounds depending on whether we test the ideal measurement or the real one.Comment: 9 pages, 3 figures. Proceedings of 17th CEWQO 201

Emerg. Infect. Dis

The multidrug-resistant (MDR) Salmonella enterica serotype Newport strain that produces CMY-2 β-lactamase(Newport MDR-AmpC) was the source of sporadic cases and outbreaks in humans in France during 2000–2005. Because this strain was not detected in food animals, it was most likely introduced into France through imported food products

Two-photon imaging and quantum holography

It has been claimed that ``the use of entangled photons in an imaging system can exhibit effects that cannot be mimicked by any other two-photon source, whatever strength of the correlations between the two photons'' [A. F. Abouraddy, B. E. A. Saleh, A. V. Sergienko, and M. C. Teich, Phys. Rev. Lett. 87, 123602 (2001)]. While we believe that the cited statement is true, we show that the method proposed in that paper, with ``bucket detection'' of one of the photons, will give identical results for entangled states as for appropriately prepared classically correlated states.Comment: 4 pages, 2 figures, REVTe

Entanglement and squeezing in a two-mode system: theory and experiment

We report on the generation of non separable beams produced via the interaction of a linearly polarized beam with a cloud of cold cesium atoms placed in an optical cavity. We convert the squeezing of the two linear polarization modes into quadrature entanglement and show how to find out the best entanglement generated in a two-mode system using the inseparability criterion for continuous variable [Duan et al., Phys. Rev. Lett. 84, 2722 (2000)]. We verify this method experimentally with a direct measurement of the inseparability using two homodyne detections. We then map this entanglement into a polarization basis and achieve polarization entanglement.Comment: submitted to J. Opt. B for a Special Issue on Foundations of Quantum Optic