Optimising the signal-to-noise ratio in measurement of photon pairs with detector arrays

To evidence multimode spatial entanglement of spontaneous down-conversion, detector arrays allow a full field measurement, without any a priori selection of the paired photons. We show by comparing results of the recent literature that electron-multiplying CCD (EMCCD) cameras allow, in the present state of technology, the detection of quantum correlations with the best signal-to-noise ratio (SNR), while intensified CCD (ICCD) cameras allow at best to identify pairs. The SNR appears to be proportional to the square root of the number of coherence cells in each image, or Schmidt number. Then, corrected estimates are derived for extended coherence cells and not very low and not space-stationary photon fluxes. Finally, experimental measurements of the SNR confirm our model

Einstein-Podolsky-Rosen paradox in twin images

Spatially entangled twin photons provide both promising resources for modern quantum information protocols, because of the high dimensionality of transverse entanglement, and a test of the Einstein-Podolsky-Rosen(EPR) paradox in its original form of position versus impulsion. Usually, photons in temporal coincidence are selected and their positions recorded, resulting in a priori assumptions on their spatio-temporal behavior. Here, we record on two separate electron-multiplying charge coupled devices (EMCCD) cameras twin images of the entire flux of spontaneous down-conversion. This ensures a strict equivalence between the subsystems corresponding to the detection of either position (image or near-field plane) or momentum (Fourier or far-field plane). We report then highest degree of paradox ever reported and show that this degree corresponds to the number of independent degrees of freedom or resolution cells, of the images

How Sustainability Ratings Might Deter "Greenwashing": A Closer Look at Ethical Corporate Communication

Of the many ethical corporate marketing practices, many firms use corporate social responsibility (CSR) communication to enhance their corporate image. Yet consumers, overwhelmed by these more or less well-founded CSR claims often have trouble identifying truly responsible firms. This confusion encourages "greenwashing" and may make CSR initiatives less effective. On the basis of attribution theory, this study investigates the role of independent sustainability ratings on consumers' responses to companies' CSR communication. Experimental results indicate the negative effect of a poor sustainability rating for corporate brand evaluations in the case of CSR communication, because consumers infer less intrinsic motives by the brand. Sustainability ratings thus could act to deter "greenwashing" and encourage virtuous firms to persevere in their CSR practices.ethical corporate marketing, CSR communication, attribution theory, sustainability ratings

How Sustainability Ratings Might Deter “Greenwashing”: A Closer Look at Ethical Corporate Communication.

Of the many ethical corporate marketing practices, many firms use corporate social responsibility (CSR) communication to enhance their corporate image. Yet consumers, overwhelmed by these more or less well-founded CSR claims, often have trouble identifying truly responsible firms. This confusion encourages “greenwashing” and may make CSR initiatives less effective. On the basis of attribution theory, this study investigates the role of independent sustainability ratings on consumers’ responses to companies’ CSR communication. Experimental results indicate the negative effect of a poor sustainability rating for corporate brand evaluations in the case of CSR communication, because consumers infer less intrinsic motives by the brand. Sustainability ratings thus could act to deter “greenwashing” and encourage virtuous firms to persevere in their CSR practices.attribution theory; ethical corporate marketing; sustainability ratings; CSR communication;

Temporal ghost imaging with twin photons

We use twin photons generated by spontaneous parametric down conversion to perform temporal ghost imaging of a single time signal. The retrieval of a binary signal containing eight bits is performed with an error rate below 1%

Computational temporal ghost imaging

Ghost imaging is a fascinating process, where light interacting with an object is recorded without resolution, but the shape of the object is nevertheless retrieved, thanks to quantum or classical correlations of this interacting light with either a computed or detected random signal. Recently, ghost imaging has been extended to a time object, by using several thousands copies of this periodic object. Here, we present a very simple device, inspired by computational ghost imaging, that allows the retrieval of a single non-reproducible, periodic or non-periodic, temporal signal. The reconstruction is performed by a single shot, spatially multiplexed, measurement of the spatial intensity correlations between computer-generated random images and the images, modulated by a temporal signal, recorded and summed on a chip CMOS camera used with no temporal resolution. Our device allows the reconstruction of either a single temporal signal with monochrome images or wavelength-multiplexed signals with color images

Synthesis kinases inhibitory potencies and in vitro antiproliferative activity of isoindigo and 7'-azaisoindigo derivatives substituted by Sonogashira cross-coupling

International audienceIn the course of structure–activity relationship studies we were interested in the synthesis of isoindigo and 7′-azaisoindigo derivatives substituted at the N-1 position by a 1-(2,3,4,6-tetra-O-acetyl-β-d-glucopyranosyl), at the 5′-position by various chains introduced by Sonogashira cross-coupling and substituted or not at the 5-position by a bromine atom. To get an insight into the substitution pattern required for the best biological potencies, their kinase inhibitory potencies and their in vitro antiproliferative activities were evaluated. The derivatives were tested toward four protein kinases (CDK5/p25, GSK3, CK1, Dyrk1A) and their in vitro antiproliferative activity was tested against two human myeloid leukaemia cell lines (K562 and HL60)

Realization of the purely spatial Einstein-Podolsky-Rosen paradox in full-field images of spontaneous parametric down conversion

We demonstrate Einstein-Podolsky-Rosen (EPR) entanglement by detecting purely spatial quantum correlations in the near and far fields of spontaneous parametric down-conversion generated in a type-2 beta barium borate crystal. Full-field imaging is performed in the photon-counting regime with an electron-multiplying CCD camera. The data are used without any postselection, and we obtain a violation of Heisenberg inequalities with inferred quantities taking into account all the biphoton pairs in both the near and far fields by integration on the entire two-dimensional transverse planes. This ensures a rigorous demonstration of the EPR paradox in its original position momentum form

Imaging spatiotemporal Hong-Ou-Mandel interference of biphoton states of extremely high Schmidt number

We report the experimental observation of a spatiotemporal Hong-Ou-Mandel (HOM) interference of biphoton states of extremely high Schmidt number. Two-photon interference of 1500 spatial modes and a total of more than 3 × 10 6 spatiotemporal modes is evidenced by measuring momentum spatial coincidences, without any prior selection of the photons in time and space coincidence, between the pixels of the far-field images of two strongly multimode spontaneous parametric down-conversion (SPDC) beams propagating through a HOM interferometer. The outgoing SPDC beams are recorded on two separate detector arrays operating in the photon-counting regime. The properties of HOM interference are investigated both in the time and space domains. We show that the two-photon interference exhibits temporal and two-dimensional spatial HOM dips with visibilities of 60% and widths in good agreement with the spatiotemporal coherence properties of the biphoton state. Moreover, we demonstrate that maxima of momentum spatial coincidences are evidenced within each image, in correspondence with these dips

Implicit Tensor-Mass solver on the GPU

International audienceThe realist and interactive simulation of deformable objects has become a challenge in Computer Graphics. For this, the Tensor-Mass model is a good candidate: it enables local solving of mechanical equations, making it easier to control deformations from collisions or tool interaction. In this paper, a GPU implementation is presented for the implicit integration scheme. Results show a notable speedup, especially for complex scenes