Reduction of Quantum Noise in Transmittance Estimation Using PhotoneCorrelated Beams

The accuracy of optical measurements at low light levels is limited by the quantum noise of the source and by the random nature of the interaction with the measured object. The source noise may be reduced by use of nonclassical photon-number squeezed light. This paper considers the use of two photon-correlated beams (generated, for example, by spontaneous parametric downconversion) to measure the optical transmittance of an object. The photons of each beam obey a random Poisson process, but are synchronized in time. One beam is used to probe the object while the other is used as a reference providing information on the realization of the random arrival of photons at the object. The additional information available by such measurement may be exploited to improve the accuracy of the measurement. Various estimators, including the maximum likelihood estimator, are considered and their performance is evaluated and compared with the measurement based on single-beam conventional (Poisson) source and maximally squeezed (fixed photon number) source. The performance advantage established in this paper depends on parameters such as the intensity of the source, the transmittance of the object, the quantum efficiency of the detectors, the background noise, and the degree of correlation of the photon numbers in the two beams

Entangled-photon Fourier optics

Entangled photons, generated by spontaneous parametric down-conversion from a second-order nonlinear crystal, present a rich potential for imaging and image-processing applications. Since this source is an example of a three-wave mixing process, there is more flexibility in the choices of illumination and detection wavelengths and in the placement of object(s) to be imaged. Moreover, this source is entangled, a fact that allows for imaging configurations and capabilities that cannot be achieved using classical sources of light. In this paper we examine a number of imaging and image-processing configurations that can be realized using this source. The formalism that we utilize facilitates the determination of the dependence of imaging resolution on the physical parameters of the optical arrangement.Comment: 41 pages, 12 figures, accepted for publication in J. Opt. Soc. Am.

Maximum-likelihood image estimation using photon-correlated beams

A theory is presented addressing the fundamental limits of image estimation in a setup that uses two photon-correlated beams. These beams have the property that their photon arrivals, as a point process, are ideally synchronized in time and space. The true image represents the spatial distribution of the optical transmittance (or reflectance) of an object. In this setup, one beam is used to probe the image while the other is used as a reference providing additional information on the actual number of photons impinging on the object. This additional information is exploited to reduce the effect of quantum noise associated with the uncertainty in the number of photons per pixel. A stochastic model for the joint statistics of the two observation matrices is developed and used to obtain a local maximum-likelihood estimator of the image. The model captures the nonideal nature of the correlation between the photons of the beams by means of a simple random translation model. The mean-square error of the estimator is evaluated and compared to the corresponding conventional techniques. Conditions for the performance advantage of the proposed estimator are examined in terms of key system parameters. The theoretical predictions are demonstrated by means of simulation

Quantum Erasure by Transverse Indistinguishability

We show that the first experiment with double-slits and twin photons detected in coincidence can be understood as a quantum eraser. The ``which path'' information is erased by transverse indistinguishability obtained by means of mode filtering in the twin conjugated beam. A delayed choice quantum eraser based on the same scheme is proposed.Comment: Submitted for publication in Optics Communication

Severity assessment of non-cystic fibrosis bronchiectasis by the FACED score

Objectives: Bronchiectasis (BE) is a major health problem associated with a high morbidity and mortality. This study aimed to determine the relation of the FACED score (a multidimensional score contributing to stratify patients into risk categories) with the severity of non-cystic fibrosis bronchiectasis (NCFB) among our population.Materials and Methods: This is a retrospective single center study of 105 consecutive patients with NCFB hospitalized for acute exacerbations (AE) at the Department of Respiratory Medicine of Fattouma Bourguiba Teaching Hospital in Monastir (Tunisia) between January 2005 and December 2017. Patients were divided into two groups (G): G1: FACED Score ≤ 2 and G2: FACED score ≥3. We compared different severity parameters of BE between the two groups.Results: The study included 105 patients with NCFB. Patients of G2 had more comorbidities (P = 0.028), an altered respiratory function with a lower forced vital capacity (G1:2.73, G2:1.33 L; P < 0.001), a decreased PaO2 (88 vs. 68 mmHg; P < 0.001), a high CO2 level (P < 0.001), and a higher number of AE/year (0.96, 2.12 AE/year; P < 0.001). Hospitalizations for AE of G2 were characterized by a lower PaO2, a higher PaCO2 (P < 0.001), a longer course of antibiotic (P < 0.001) with an extended hospitalization (P = 0.007). An ultimate evolution toward chronic respiratory failure was more common in G2 (P < 0.001).Conclusion: A high FACED score is associated with more symptoms, an altered respiratory function, a higher number and more severe AE, more health-care utilization with worse outcomes. Further studies are necessary to evaluate the impact of such scales in clinical practice

Adénocarcinome pulmonaire primitif: expérience d’un centre hospitalier tunisien

La fréquence de l'adénocarcinome pulmonaire primitif est en nette augmentation au dépend des autres types histologiques de cancer bronchique primitif. En effet, il représente environ 40% des cas des carcinomes bronchiques non à petites cellules (CNPC). Il se distingue par certaines particularités. Décrire les aspects épidémiologiques, cliniques, thérapeutiques et évolutifs de l'adénocarcinome pulmonaire primitif. Etuderétrospective incluant 322 patients porteurs d'adénocarcinome pulmonaire primitif, hospitalisés au service de pneumologie du centre hospitalouniversitaire de Monastir (Tunisie) entre janvier 1990 et septembre 2013. L'âge moyen de nos patients était de 59,4 ans. 25,8% sont âgés de moins de 50 ans. Une prédominance masculine (86,3%) a été notée. 81,7% des patients étaient tabagiques. La symptomatologie respiratoire était dominée par la douleur thoracique (57,1%) et la toux (46%). Au moment du diagnostic, 73,3 % des patients étaient au stade métastatique. Les localisations secondaires les plus fréquentes étaient le poumon controlatéral (25,5%), la plèvre (21,1%) et l'os (19,25%). La prise en charge thérapeutique s'est basée essentiellement sur la chimiothérapie (48,5% des cas). Seulement 10,3% des patients ont bénéficié d'un traitement chirurgical. La médiane de survie de nos patients était de 6 mois avec une survie à 1 an, 3 ans et 5 ans respectivement de 25,9%, 3,2% et 2%. L'adénocarcinome bronchique primitif est un sous type histologique particulier parmi les cancers broncho-pulmonaires primitifs. Son incidence est en augmentation depuis une vingtaine d'année. Malgré les progrès thérapeutiques, il reste de mauvais pronostic

Pneumonie organisée révélatrice d’une polymyosite

Les polymyosites (PM) sont des connectivites très rares, d'étiologie inconnue, dotées d'un grand   polymorphisme clinique et évolutif. Elles peuvent être associées à d'autres manifestations viscérales  notamment pulmonaires telles que la pneumopathie interstitielle. Ces complications respiratoires sont  souvent associées à un taux de mortalité élevé. Les cas de pneumonie organisée révélatrice de polymyosite sont rarement rapportés dans la littérature et de description récente. Nous rapportons l'observation d'une patiente âgée de 53 ans qui a présenté, 14 mois après avoir porter le diagnostic d'une pneumonie organisée, des myalgies diffuses, un oedème des membres inférieurs et une élévation des enzymes musculaires. La biopsie musculaire a confirmé le diagnostic de la myosite. L'évolution était favorable sous corticothérapie. Le traitement de la PO associée au PM n'est pas clairement établi. La corticothérapie constitue le traitement de première intention.Key words: Pneumonie organisée, polymyosite, connectivite

Role of entanglement in two-photon imaging

The use of entangled photons in an imaging system can exhibit effects that cannot be mimicked by any other two-photon source, whatever the strength of the correlations between the two photons. We consider a two-photon imaging system in which one photon is used to probe a remote (transmissive or scattering) object, while the other serves as a reference. We discuss the role of entanglement versus correlation in such a setting, and demonstrate that entanglement is a prerequisite for achieving distributed quantum imaging.Comment: 15 pages, 2 figure

A method for reaching detection efficiencies necessary for optical loophole-free Bell experiments

A method for preparing a loophole-free four-photon Bell experiments which requires a detection efficiency of 67% is proposed. It enables realistic detection efficiencies of 75% at a visibility of 85%. Two type-II crystals each down convert one correlated photon pair and we entangle one photon from one pair with one photon from the other pair on a highly transparent beam splitter. The entanglement selects two other conjugate photons into a Bell state. Wide solid angles for the conjugate photons then enable us to collect close to 100% of them. The cases when both photon pairs come from only one of the two crystals are successfully taken into account. Hardy's equalities are discussed.Comment: RevTeX, 20 pages, 2figures, Author's URL http://m3k.grad.hr/pavici