A quantum study of multi-bit phase coding for optical storage

We propose a scheme which encodes information in both the longitudinal and spatial transverse phases of a continuous-wave optical beam. A split detector-based interferometric scheme is then introduced to optimally detect both encoded phase signals. In contrast to present-day optical storage devices, our phase coding scheme has an information storage capacity which scales with the power of the read-out optical beam. We analyse the maximum number of encoding possibilities at the shot noise limit. In addition, we show that using squeezed light, the shot noise limit can be overcome and the number of encoding possibilities increased. We discuss a possible application of our phase coding scheme for increasing the capacities of optical storage devices.Comment: 8 pages, 7 figures (Please email author for a PDF file if the manuscript does not turn out properly

Nano-displacement measurements using spatially multimode squeezed light

We demonstrate the possibility of surpassing the quantum noise limit for simultaneous multi-axis spatial displacement measurements that have zero mean values. The requisite resources for these measurements are squeezed light beams with exotic transverse mode profiles. We show that, in principle, lossless combination of these modes can be achieved using the non-degenerate Gouy phase shift of optical resonators. When the combined squeezed beams are measured with quadrant detectors, we experimentally demonstrate a simultaneous reduction in the transverse x- and y- displacement fluctuations of 2.2 dB and 3.1 dB below the quantum noise limit.Comment: 21 pages, 9 figures, submitted to "Special Issue on Fluctuations & Noise in Photonics & Quantum Optics" of J. Opt.

Continuous-Variable Spatial Entanglement for Bright Optical Beams

A light beam is said to be position squeezed if its position can be determined to an accuracy beyond the standard quantum limit. We identify the position and momentum observables for bright optical beams and show that position and momentum entanglement can be generated by interfering two position, or momentum, squeezed beams on a beam splitter. The position and momentum measurements of these beams can be performed using a homodyne detector with local oscillator of an appropriate transverse beam profile. We compare this form of spatial entanglement with split detection-based spatial entanglement.Comment: 7 pages, 3 figures, submitted to PR

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

Distal humerus fractures in patients over 65: Complications

SummaryIntroductionFractures of the distal humerus in patients over the age of 65 remain a therapeutic challenge. Treatment options include conservative treatment, internal fixation or total elbow arthroplasty. The complications of these different treatment options were evaluated in a multicentre study.Materials and methodsFour hundred and ninety-seven medical records were evaluated. A retrospective study was performed in 410 cases: 34 received conservative treatment, 289 internal fixation and 87 underwent total elbow arthroplasty. A prospective study was performed in 87 cases: 22 received conservative treatment, 53 internal fixation, and 12 underwent total elbow arthroplasty. Patients were evaluated after at least 6 months follow-up.ResultsThe rate of complications was 30% in the retrospective study and 29% in the prospective study. The rate of complications in the conservative treatment group was 60%, and the main complication was essentially malunion. The rate of complications was 44% in the internal fixation group and included neuropathies, mechanical failure or wound dehiscence. Although complications only developed in 23% of total elbow arthroplasties, they were often more severe than those following other treatments.DiscussionComplications develop in one out of three patients over 65 with distal humerus fractures. Three main types of complications were identified. Neuropathies especially of the ulnar nerve, especially during arthroplasty, must always be identified, the nerve requiring isolation and transposition. Bone complications, due principally to mechanical failure, were found following internal fixation. Despite technical progress, care must be taken not to favor excessive utilization of this treatment option in complex fractures on fragile bone. Although there were relatively fewer complications with total elbow arthroplasty they were more difficult to treat. Ossifications were frequent whatever the surgical option and can jeopardize the functional outcome.Level of evidenceLevel IV

Un outil de simulation adapté à la gestion des ressources en eau du territoire dans le cadre d’une démarche participative

National audienceThis paper presents a simulation tool adapted to water resources management on a territorial scale, as part of a participatory process. This tool combines the PILOTE-TER crop model and the Olympe technico-economical simulator. PILOTE-TER links the crop model Pilote developed by Irstea with a database managed through a graphical interface. It makes possible to use the Pilote model to evaluate the water demand and the crop yield at the scale of the field, the farm and the territory. The parameters of the model come from the results of experiments performed by Irstea. PILOTE-TER is linked to the technico-economic simulator Olympe (from INRA) to produce economical indicators. These tools are used for a territorial representation of agriculture build with local stakeholders, allowing the comparison of several scenarios (based on economical, policy or climate changes).Cet article présente un outil de simulation adapté à la gestion de ressources en eau à l’échelle d’un territoire dans le cadre de démarches participatives. Cet outil associe un modèle de culture, Pilote Ter, et le simulateur technico-économique Olympe. Pilote Ter intègre le modèle de culture Pilote développé par Irstea et un système de base de données géré à partir d’une interface graphique. Il permet une utilisation territorialisée du modèle de culture Pilote pour évaluer la demande en eau agricole et les rendements des cultures à l’échelle de la parcelle, de l’exploitation agricole et du territoire. Le paramétrage du modèle s’appuie sur les résultats des expérimentations menées par Irstea. Pilote Ter est couplé au simulateur technico-économique Olympe (INRA) pour produire des indicateurs économiques. Ces deux logiciels sont le support d’une représentation de l’agriculture du territoire co-construite avec les acteurs locaux permettant l’étude de scénarios économiques, réglementaires ou climatiques

Zeeman slowers made simple with permanent magnets in a Halbach configuration

We describe a simple Zeeman slower design using permanent magnets. Contrary to common wire-wound setups no electric power and water cooling are required. In addition, the whole system can be assembled and disassembled at will. The magnetic field is however transverse to the atomic motion and an extra repumper laser is necessary. A Halbach configuration of the magnets produces a high quality magnetic field and no further adjustment is needed. After optimization of the laser parameters, the apparatus produces an intense beam of slow and cold 87Rb atoms. With a typical flux of 1 - 5 \times 10^10 atoms/s at 30 ms^-1, our apparatus efficiently loads a large magneto-optical trap with more than 10^10 atoms in one second, which is an ideal starting point for degenerate quantum gases experiments.Comment: 8+6 pages (article + appendices: calculation details, probe and oven description, pictures), 18 figures, supplementary material (movie, Mathematica programs and technical drawings

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

Quantum squeezing of optical dissipative structures

We show that any optical dissipative structure supported by degenerate optical parametric oscillators contains a special transverse mode that is free from quantum fluctuations when measured in a balanced homodyne detection experiment. The phenomenon is not critical as it is independent of the system parameters and, in particular, of the existence of bifurcations. This result is a consequence of the spatial symmetry breaking introduced by the dissipative structure. Effects that could degrade the squeezing level are considered.Comment: 4 pages and a half, 1 fugure. Version to appear in Europhysics Letter