Quantum technology: single-photon source

This report is a synthesis of my master thesis internship at the National Institute of Informatics (NII) in Tokyo, Japan, that lasted during the summer of year 2012. I worked in the Quantum Information Science Theory (QIST) group under supervision of Prof. Kae Nemoto and Dr. Simon Devitt. This group works on theoretical and experimental implementations of quantum information science. The aim of my project was to study and improve quantum optical systems. I first studied different fields and systems of quantum information science. Then I focused my research on single-photon sources, entangled photon sources and interferometric photonic switches. Finally, I found some strategies to design an efficient and optimized single-photon source that could be built with today's technologies. This report describes in details the created and optimized design of a single-photon source based on time and space multiplexing of Spontaneous Parametric Downconversion (SPDC) sources.Comment: Research extract of Master thesis report. Defended in September 2012. Declassified by the NII in February 201

Quantum Technology: Single-Photon Source - arXiv research extract only

This report is a research extract of my master thesis internship at the National Institute of Informatics (NII) in Tokyo, Japan. This report describes in details the created and optimized design of a single-photon source based on time and space multiplexing of Spontaneous Parametric Downconversion (SPDC) sources

SPDC based single-photon source with frequency up-conversion multiplexed architecture

We describe a single-photon source based on an array of spontaneous parametric down-conversion (SPDC) modules multiplexed by an integrated structure composed of electro-optic switches and delay wave-guides. The suggested optical device allows to increase the photon source frequency compared to the SPDC laser pumping frequency and enhances both stability, controllability, and efficiency. This device transforms the spatial multiplexing into a temporal multiplexing with temporary photon storage. The photons are stored into different delay lines and temporally sequentialized. This train of photon can then be used in high frequency emission (up-conversion) and compensation of photon lack among the pumping cycles (down-conversion). The implementation consists of a crossed multiplexed architecture using electro-optic switches. The architecture first drives the downconverters array outputs into several layers of delay lines organized in shared and by-passable binary delay register. The architecture then includes a routing tree driving all the photons into a single output

Mod\'elisation multi-niveaux dans AA4MM

In this article, we propose to represent a multi-level phenomenon as a set of interacting models. This perspective makes the levels of representation and their relationships explicit. To deal with coherence, causality and coordination issues between models, we rely on AA4MM, a metamodel dedicated to such a representation. We illustrate our proposal and we show the interest of our approach on a flocking phenomenon

Latent variables and the network perspective

International audienceWe discuss the latent variables construct, particularly in regard to the following: that latent variables are considered as the sole explanatory factor of a disorder; that pragmatic concerns are ignored; and that the relationship of these variables to biological markers is not addressed. Further, we comment on the relationship between bridge symptoms and causality, and discuss the proposal in relationship to other constructs (endophenotypes, connectionist-inspired networks)

Modélisation de l'impact de la dépression sur le système cardiovasculaires (utilisation du modèle de stress chronique imprédictible chez la souris)

La dépression est considérée comme un facteur de risque capable de prédire l apparition de maladies cardiovasculaires. L'objectif de ce travail est de développer un modèle animal capable de reproduire les altérations vasculaires et la résistance aux traitements observés chez les patients dépressifs qui présentent des risques cardiovasculaires. La formation d'athérosclérose et la fonction endothéliale sont évaluées chez des souris exposées au stress chronique imprédictible (UCMS) qui constitue un modèle valide de dépression et les effets comportementaux d un traitement antidépresseur sont évalués chez des souris UCMS recevant un régime hyper lipidique. Nos résultats montrent que l UCMS induit un état de type dépressif et un dysfonctionnement endothélial qui n est pas suffisant pour induire de l athérosclérose. Le régime hyper lipidique abolit les effets antidépresseurs de la fluoxétine. Ces résultats suggèrent que ce modèle reproduit les altérations physiologiques mais non morphologique aussi bien que la résistance aux traitements des patients dépressifs présentant des facteurs de risques cardiovasculaires.Epidemiologic studies have demonstrated that depressive symptoms can predict cardiovascular disease in healthy patients. The purpose of this study was to develop an animal model able to reproduce the vascular alterations and the treatment resistance observed in depressed subjects who develop vascular disease. Atherosclerotic plaque formation and endothelial dysfunction were assessed in mice exposed to the Unpredictable Chronic Mild Stress (UCMS) that constitute a reliable animal model of depression and the reversal effect of antidepressant was assessed in UCMS mice fed a high fat diet. Our results show that high fat diet regimen prevented the reversal effect of chronic fluoxetine treatment on UCMS-induced depressive-like behaviour. Moreover, UCMS-induced endothelial dysfunction was not associated with atherosclerotic plaque formation. These findings suggest that this model can reproduce the physiological but not the morphological vascular alterations observed in depressed patients who develop vascular disease as well as the reported treatment resistance in depressed patients also suffering from cardiovascular risk factor.TOURS-Bibl.électronique (372610011) / SudocSudocFranceF

Energy-Efficient Digital Design Through Inexact and Approximate Arithmetic Circuits

Inexact and approximate circuit design is a promising approach to improve performance and energy efficiency in technology-scaled and low-power digital systems. Such strategy is suitable for error tolerant applications involving perceptive or statistical outputs. This paper reviews two established techniques applicable to arithmetic units: circuit pruning and carry speculation. A critical comparative study is carried out considering several error metrics

Multi-level Modeling as a Society of Interacting Models

We propose to consider a multi-level representation from a multi-modeling point of view. We define a framework to better specify the concepts used in multi-level modeling and their relationships. This framework is implemented through the AA4MM meta-model, which benefits from a middleware layer. This meta-model uses the multi-agent paradigm to consider a multi-model as a society of interacting models. We extend this meta-model to consider multi-level modeling and present a proof of concept of a collective motion example where we show the ability of this approach to rapidly change from one pattern of interaction to another one by reusing some of the meta-model's components

Near/Sub-Threshold Circuits and Approximate Computing: The Perfect Combination for Ultra-Low-Power Systems

While sub/near-threshold design offers the minimal power and energy consumption, such approach strongly deteriorates circuit performances and robustness against PVT (process/voltage/temperature) variations, leading to gigantic speed penalties and large silicon areas. Inexact and approximate circuit design can address these issues by trading calculation accuracy for better silicon area, circuit speed and even better power consumption. This paper reviews and proposes improvements for two approximate computing techniques applicable to arithmetic circuits: gate-level pruning and carry speculation. A critical study is then carried out considering several error metrics, and for the first time, those techniques are combined to produce approximate adders showing even higher gains at similar error levels. It is then shown that those techniques can be applied to a sub-threshold library to mitigate the large variability