High-visibilty two-photon interference at a telecom wavelength using picosecond regime separated sources

We report on a two-photon interference experiment in a quantum relay configuration using two picosecond regime PPLN waveguide based sources emitting paired photons at 1550 nm. The results show that the picosecond regime associated with a guided-wave scheme should have important repercussions for quantum relay implementations in real conditions, essential for improving both the working distance and the efficiency of quantum cryptography and networking systems. In contrast to already reported regimes, namely femtosecond and CW, it allows achieving a 99% net visibility two-photon interference while maintaining a high effective photon pair rate using only standard telecom components and detectors.Comment: to appear in PRA as a rapid communicatio

Onde ou particule, le photon défie toujours l’intuition

La dualité onde/particule se teste la plupart du temps à l’aide de photons uniques envoyés dans un interféromètre de Mach-Zehnder équilibré. On peut alors observer des comportements considérés comme mutuellement exclusifs, à savoir ondulatoire (présence d’interférences) ou corpusculaire (absence d’interférences) selon la présence ou l’absence de la lame séparatrice en sortie de l’interféromètre. Nous présentons un nouveau type d’expérience de complémentarité dans laquelle cette lame séparatrice est préparée dans une superposition cohérente lui permettant d’être à la fois présente et absente. Cette préparation est « activée » grâce à l’emploi de paires de photons intriqués en polarisation. L’un des photons, dit test, est envoyé dans l’interféromètre et est détecté alors que son jumeau, dit corroborant, permet de déterminer si un comportement de type ondulatoire, corpusculaire ou intermédiaire a été observé pour le photon test. En manipulant l’état de polarisation du photon corroborant et la phase de l’interféromètre du photon test, nous observons une transition continue entre aspects ondulatoire et corpusculaire, signature forte de la notion de complémentarité introduite par Bohr et donc de la non exclusivité de ces comportements

Structural Brain Anomalies and Chronic Pain: A Quantitative Meta-Analysis of Gray Matter Volume

The diversity of chronic pain syndromes and the methods employed to study them make integrating experimental findings challenging. This study performed coordinate-based meta-analyses using voxel-based morphometry imaging results to examine gray matter volume (GMV) differences between chronic pain patients and healthy controls. There were 12 clusters where GMV was decreased in patients compared with controls, including many regions thought to be part of the “pain matrix” of regions involved in pain perception, but also including many other regions that are not commonly regarded as pain-processing areas. The right hippocampus and parahippocampal gyrus were the only regions noted to have increased GMV in patients. Functional characterizations were implemented using the BrainMap database to determine which behavioral domains were significantly represented in these regions. The most common behavioral domains associated with these regions were cognitive, affective, and perceptual domains. Because many of these regions are not classically connected with pain and because there was such significance in functionality outside of perception, it is proposed that many of these regions are related to the constellation of comorbidities of chronic pain, such as fatigue and cognitive and emotional impairments. Further research into the mechanisms of GMV changes could provide a perspective on these findings. PERSPECTIVE: Quantitative meta-analyses revealed structural differences between brains of individuals with chronic pain and healthy controls. These differences may be related to comorbidities of chronic pain

Clinical Outcomes and Bacterial Characteristics of Carbapenem-Resistant Acinetobacter baumannii Among Patients from Different Global Regions

Abstract Background Carbapenem-resistant Acinetobacter baumannii (CRAb) is one of the most problematic antimicrobial-resistant bacteria. We sought to elucidate the international epidemiology and clinical impact of CRAb. Methods In a prospective observational cohort study, 842 hospitalized patients with a clinical CRAb culture were enrolled at 46 hospitals in five global regions between 2017 and 2019. The primary outcome was all-cause mortality at 30 days from the index culture. The strains underwent whole-genome analysis. Results Of 842 cases, 536 (64%) represented infection. By 30 days, 128 (24%) of the infected patients died, ranging from 1 (6%) of 18 in Australia-Singapore to 54 (25%) of 216 in the United States and 24 (49%) of 49 in South-Central America, whereas 42 (14%) of non-infected patients died. Bacteremia was associated with a higher risk of death compared with other types of infection (40 [42%] of 96 vs. 88 [20%] of 440). In a multivariable logistic regression analysis, bloodstream infection and higher age-adjusted Charlson comorbidity index were independently associated with 30-day mortality. Clonal group 2 (CG2) strains predominated except in South-Central America, ranging from 216 (59%) of 369 in the United States to 282 (97%) of 291 in China. Acquired carbapenemase genes were carried by 769 (91%) of the 842 isolates. CG2 strains were significantly associated with higher levels of meropenem resistance, yet non-CG2 cases were over-represented among the deaths compared with CG2 cases. Conclusions CRAb infection types and clinical outcomes differed significantly across regions. While CG2 strains remained predominant, non-CG2 strains were associated with higher mortality. ClinicalTrials.gov #NCT0364622