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Tutorial: Shaping the Spatial Correlations of Entangled Photon Pairs
No full textInternational audienceQuantum imaging enhances imaging systems performance, potentially surpassing fundamental limits such as noise and resolution. However, these schemes have limitations and are still a long way from replacing classical techniques. Therefore, there is a strong focus on improving the practicality of quantum imaging methods, with the goal of finding real-world applications. With this in mind, in this tutorial we describe how the concepts of classical light shaping can be applied to imaging schemes based on entangled photon pairs. We detail two basic experimental configurations in which a spatial light modulator is used to shape the spatial correlations of a photon pair state and highlight the key differences between this and classical shaping. We then showcase two recent examples that expand on these concepts to perform aberration and scattering correction with photon pairs. We include specific details on the key steps of these experiments, with the goal that this can be used as a guide for building photon-pair-based imaging and shaping experiments
Anticipation under the Human Right to Science: Concepts, Stakes and Specificities
No full textInternational audienc
Exploiting separation-dependent coherence to boost optical resolution
No full textInternational audienceThe problem of resolving point-like light sources not only serves as a benchmark for optical resolution but also holds various practical applications ranging from microscopy to astronomy. In this research, we aim to resolve two thermal sources sharing arbitrary mutual coherence using the spatial mode demultiplexing technique. Our analytical study includes scenarios where the coherence and the emission rate depend on the separation between the sources, and is not limited to the faint sources limit. We consider the fluorescence of two interacting dipoles to demonstrate that the dependence of emission characteristics on the parameter of interest can boost the sensitivity of the estimation and noticeably prolong the duration of information decay
"La naissance du Bouddha" sur Colligere : le carnet des bibliothèques et archives du Collège de France
No full texthttps://archibibscdf.hypotheses.org/15605Billet présentant la sculpture népalaise en bronze doré représentant la reine Mâyâ donnant naissance au Bouddha (SL-16, XIXe siècle) offerte à l'Institut de civilisation indienne (aujourd'hui centre d'études indiennes et centrasiatiques) en 1929 par la Maharaja Chandra Shumsher, à l'occasion de l'exposition de cette œuvre récemment restaurée dans la salle de lecture du pôle Mondes asiatiques de l'Institut des civilisations du Collège de France
From tension to buckling - a mechanical transition underlies the puzzle-shape morphogenesis of histoblasts in the Drosophila epidermis
No full textThe polygonal shape of cells in proliferating epithelia is a result of the tensile forces of the cytoskeletal cortex and packing geometry set by the cell cycle 1,2 . In the larval Drosophila epidermis, two cell populations, histoblasts and larval epithelial cells, compete for space as they grow on a limited body surface. They do so in the absence of cell divisions. We report a striking morphological transition of histoblasts during larval development, where they change from a tensed network configuration with straight cell outlines at the level of adherens junctions to a highly folded morphology. The apical surface of histoblasts shrinks while their growing adherens junctions fold, forming deep lobules. Volume increase of growing histoblasts is accommodated basally, compensating for the shrinking apical area. The folded geometry of apical junctions resembles elastic buckling, and we show that the imbalance between the shrinkage of the apical domain of histoblasts and the continuous growth of junctions triggers buckling. Our model is supported by laser dissections and optical tweezer experiments together with computer simulations. Our analysis pinpoints the ability of histoblasts to store mechanical energy to a much greater extent than most other epithelial cell types investigated so far, while retaining the ability to dissipate stress on the hours time scale. Finally, we propose a possible mechanism for size regulation of histoblast apical size through the lateral pressure of the epidermis, driven by the growth of cells on a limited surface. Buckling effectively compacts histoblasts at their apical plane and may serve to avoid physical harm to these adult epidermis precursors during larval life. Our work indicates that in growing non-dividing cells, compressive forces, instead of tension, may drive cell morphology
Mémo visuel de neurosciences - 2e édition: Du neurone aux sciences cognitives
No full textL’objectif de cet ouvrage est de présenter, de manière synthétique et illustrée, l’ensemble des connaissances actuelles sur le fonctionnement du système nerveux, depuis les bases moléculaires jusqu’aux fonctions intégrées.Constitué de plus de 150 fiches avec schémas et photos en couleurs, ce livre vous permettra de réviser rapidement les notions essentielles de neurosciences. L’image a volontairement été privilégiée, le texte d’accompagnement résumant les idées essentielles.Cette seconde édition a été actualisée en fonction des dernières connaissances scientifiques et augmentée d’une annexe sur les principales maladies neurodégénérative
Environmentally-Responsible Demand: Irresponsible Lobbying? *
No full textTravail de recherhe : Collège de France Chaire Économie des institutions, de l'innovation et de la croissance (Professeur Aghion)How do firms respond to rising environmental concerns of consumers? We investigate this question for the automotive industry in the US using a shift-share instrumental variable approach. We construct a novel dataset at the firm-level to instrument changes in household preferences with natural disasters. Our findings suggest that firms not only engage in cleaner innovation but also increase their lobbying on environmental topics. We show that the increase in environmental lobbying and clean patenting follow the same dynamics which points to a complementarity between the two strategies. These results can be understood as firms using lobbying to increase the value of clean patents: higher environmental standards tailored to the firm’s new clean technologies diminish the competition the firm faces
Exploring the maternal inheritance transmitted by the oocyte to its progeny
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High-field immiscibility of electrons belonging to adjacent twinned bismuth crystals
No full textInternational audienceAbstract Bulk bismuth has a complex Landau spectrum. The small effective masses and the large g-factors are anisotropic. The chemical potential drifts at high magnetic fields. Moreover, twin boundaries further complexify the interpretation of the data by producing extra anomalies in the extreme quantum limit. Here, we present a study of angle dependence of magnetoresistance up to 65 T in bismuth complemented with Nernst, ultrasound, and magneto-optic data. All observed anomalies can be explained in a single-particle picture of a sample consisting of two twinned crystals tilted by 108° and with two adjacent crystals keeping their own chemical potentials despite a shift between chemical potentials as large as 68 meV at 65 T. This implies an energy barrier between adjacent twinned crystals reminiscent of a metal- semiconductor Schottky barrier or a p-n junction. We argue that this barrier is built by accumulating charge carriers of opposite signs across a twin boundary