Metrology and 1/f noise: linear regressions and confidence intervals in flicker noise context

1/f noise is very common but is difficult to handle in a metrological way. After having recalled the main characteristics of stongly correlated noise, this paper will determine relationships giving confidence intervals over the arithmetic mean and the linear drift parameters. A complete example of processing of an actual measurement sequence affected by 1/f noise will be given

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

Multi-imaging and Bayesian estimation for photon counting with EMCCD's

A multi-imaging strategy is proposed and experimentally tested to improve the accuracy of photon counting with an electron multiplying charge-coupled device (EMCCD), by taking into account the random nature of its on-chip gain and the possibility of multiple photo-detection events on one pixel. This strategy is based on Bayesian estimation on each image, with a priori information given by the sum of the images. The method works even for images with large dynamic range, with more improvement in the low light level areas. In these areas, two thirds of the variance added by the EMCCD in a conventional imaging mode are removed, making the physical photon noise predominant in the detected image.Comment: 19 page

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

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

Impact of Pump Quality on the Performances of Fiber Optical Parametric Amplifiers

International audienceThe principle of operation of fibre optical parametric amplifiers is revisited with a special attention to the pump wave characteristics ranging from the monochromatic coherent case to the incoherent one

Vermonters’ Opinions on Low-Dose CT Lung Cancer Screening

Introduction: Lung cancer is the number one cause of cancer death among men and women in Vermont and the United States. Smoking increases the risk of lung cancer—nearly 90% of lung cancer is due to smoking. Frequently, lung cancers do not present clinically until they are advanced stage and therefore prognosis is poor. However, if detected early lung cancers are more operable and patients have better outcomes. In December 2013 the US Preventive Services Task Force released new guidelines for lung cancer screening among current and former smokers ages 55 to 80. It is recommended that current and former (within 15 years of quitting) smokers of 30 pack years receive an annual low-dose CT scan. The objective of this project was to assess the level of knowledge and attitudes towards lung cancer screening with low-dose CT scanning among Vermonters in the Burlington area.https://scholarworks.uvm.edu/comphp_gallery/1205/thumbnail.jp