Spatio-temporal entanglement of twin photons: an intuitive picture

We draw an intuitive picture of the spatio-temporal properties of the entangled state of twin photons, where they are described as classical wave-packets. This picture predicts a precise relation between their temporal and transverse spatial separations at the crystal output. The space-time coupling described by classical arguments turns out to determine in a precise way the spatio-temporal structure of the quantum entanglement, analysed by means of the biphotonic correlation and of the Schmidt dimensionality of the entanglement.Comment: 12 pages, 3 figure

Tailoring the spatiotemporal structure of biphoton entanglement in type-I parametric down-conversion

We investigate the spatiotemporal structure of the biphoton entangled state produced by parametric down-conversion (PDC) at the output face of the nonlinear crystal. We analyze the geometry of biphoton correlation for different gain regimes (from ultralow to high), different crystal lengths, and different tuning angles of the crystal. While for collinear or quasicollinear phase matching a X-shaped geometry, nonfactorizable in space and time, dominates, in the highly noncollinear conditions we observe a remarkable transition to a factorizable geometry. We show that the geometry of spatiotemporal correlation is a consequence of the angle-frequency relationship imposed by phase matching and that the fully spatiotemporal analysis provides a key to control the spatiotemporal properties of the PDC entangled state and in particular to access a biphoton localization in time and space in the femtosecond and micrometer range, respectively

High-sensitivity imaging with multi-mode twin beams

Twin entangled beams produced by single-pass parametric down-conversion (PDC) offer the opportunity to detect weak amount of absorption with an improved sensitivity with respect to standard techniques which make use of classical light sources. We propose a differential measurement scheme which exploits the spatial quantum correlation of type II PDC to image a weak amplitude object with a sensitivity beyond the standard quantum limit imposed by shot-noise.Comment: 13 pages, 8 figure

La triade : une stratégie de supervision à redéfinir!

La présente étude descriptive à caractère exploratoire s’inscrit dans le contexte des réformes en éducation au Québec, plus particulièrement au baccalauréat en enseignement de l’éducation physique et à la santé (ÉPS). L’un des principaux défis qui touchent la formation initiale est sans doute celui d’assurer le développement des compétences professionnelles des futurs enseignants, notamment en cours de stage. À cet égard, il apparaît pertinent d’actualiser la stratégie de supervision pédagogique privilégiée lors des stages en ÉPS à l’Université du Québec à Trois-Rivières : la triade (stagiaire, enseignant associé et superviseur universitaire). Dans le cadre de la stratégie de supervision réalisée en triade, les objectifs de l’étude consistent à approfondir les représentations de chacun des acteurs en référence aux compétences professionnelles, à décrire les types de savoirs mobilisés et à définir les conditions favorables à la supervision. Les résultats issus d’un questionnaire auquel ont répondu les membres de la triade (N = 42) actifs à la session d’hiver 2007 révèlent certaines divergences entourant les représentations et les savoirs relatifs à la supervision en triade. La nécessité d’une vision commune en matière de développement professionnel conjuguée à la pertinence de points de vue jugés complémentaires entre les formateurs est discutée.This exploratory and descriptive study was conducted in the context of Québec’s education reforms, particularly in terms of teacher training for physical education and health. (PEH). Without a doubt, one of the major challenges of initial training is ensuring professional skill development among the future teachers during their practicums. To this effect, is seems important to update the pedagogical supervision strategy in place at University of Québec in Trois-Rivières: the triad: student teacher, supervising teacher, and university supervisor. In the framework of the triad supervision strategy, the objectives of the study consist of deepening the understanding each actor has of professional skills, describing the types of knowledge mobilized and identifying favourable supervision conditions. The results of a questionnaire given to the triad members (N = 42) who were active in the winter of 2007 session reveal certain discrepancies in their ideas and knowledge about triad supervision. The need for a common professional development vision and the relevance of complementary points of view among the trainers is discussed.El presente estudio descriptivo de tipo exploratorio se inscribe en el contexto de las reformas educativas en Quebec, más específicamente en formación docente en educación física y salud (EFS). Uno de los principales retos que tocan a la formación inicial es sin duda el de garantizar el desarrollo de las habilidades profesionales de los futuros maestros, sobre todo durante el período de práctica. Al respecto, es pertinente actualizar la estrategia de supervisión pedagógica privilegiada durante los períodos de práctica en EFS en la Universidad de Quebec en Trois-Rivières: la triada (practicante, maestro asociado y supervisor universitario). En el marco de la estrategia de supervisión en triada, los objetivos del estudio consisten en profundizar las representaciones de cada uno de los actores en lo que se refiere a las habilidades profesionales, describir los tipos de saber movilizados e identificar las condiciones que favorecen la supervisión. Los resultados provenientes de un cuestionario aplicado a los miembros de la triada (N=42) activos durantes la sesión del invierno de 2007 muestran ciertas divergencias en torno a las representaciones y los saberes relativos a la supervisión en triada. Se discute la necesidad de una visión común en materia de desarrollo profesional conjugada con la pertinencia de puntos de vista juzgados como complementarios entre los formadores

Generation of Complex Quantum States Via Integrated Frequency Combs

The generation of optical quantum states on an integrated platform will enable low cost and accessible advances for quantum technologies such as secure communications and quantum computation. We demonstrate that integrated quantum frequency combs (based on high-Q microring resonators made from a CMOS-compatible, high refractive-index glass platform) can enable, among others, the generation of heralded single photons, cross-polarized photon pairs, as well as bi- and multi-photon entangled qubit states over a broad frequency comb covering the S, C, L telecommunications band, constituting an important cornerstone for future practical implementations of photonic quantum information processing

Integrated Generation of High-dimensional Entangled Photon States and Their Coherent Control

We demonstrate the generation of high-dimensional entangled photon pairs with a Hilbert-space dimensionality larger than 100 from an on-chip nonlinear microcavity, and introduce a coherent control scheme using standard telecommunications components

Counterpropagating frequency mixing with terahertz waves in diamond

Frequency conversion by means of Kerr-nonlinearity is one of the most common and exploited nonlinear optical processes in the UV, visible, IR and Mid-IR spectral regions. Here we show that wave mixing of an optical field and a Terahertz wave can be achieved in diamond, resulting in the frequency conversion of the THz radiation either by sum- or difference-frequency generation. In the latter case, we show that this process is phase-matched and most efficient in a counter-propagating geometry

On-chip Quantum State Generation by Means of Integrated Frequency Combs

Summary form only given. This paper investigates different approaches to generate optical quantum states by means of integrated optical frequency combs. These include the generation of multiplexed heralded single-photons, the first realization of cross-polarized photon-pairs on a photonic chip, the first generation of multiple two-photon entangled states, and the first realizations of multi-photon entangled quantum states on a photonic chip

CCD-based imaging and 3D space--time mapping of terahertz fields via Kerr frequency conversion

We investigate the spatially and temporally resolved four-wave mixing of terahertz (THz) fields and optical pulses in large-bandgap dielectrics, such as diamond. We show that it is possible to perform beam profiling and space–time resolved mapping of THz fields by encoding the spatial information into an optical signal, which can then be recorded by a standard CCD camera