Comparing different approaches for generating random numbers device-independently using a photon pair source

What is the most efficient way to generate random numbers device-independently using a photon pair source based on spontaneous parametric down conversion (SPDC)? We consider this question by comparing two implementations of a detection-loophole-free Bell test. In particular, we study in detail a scenario where a heralded single photon source (HSPS) is used to herald path-entangled states, i.e. entanglement between two spatial modes sharing a single photon and where non-locality is revealed using photon counting preceded by small displacement operations. We start by giving a theoretical description of such a measurement. We then show how to optimize the Bell-CHSH violation through a non-perturbative calculation, taking the main experimental imperfections into account. We finally bound the amount of randomness that can be extracted and compare it to the one obtained with the conventional scenario using photon pairs entangled e.g. in polarization and analyzed through photon counting. While the former requires higher overall detection efficiencies, it is far more efficient in terms of both the entropy per experimental run and the rate of random bit generation.Comment: 12 pages, 5 figure

Cardiopatia isquêmica em pacientes com diabete melito tipo 2 : análise dos criterios diagnosticos e dos fatores de risco associados

A cardiopatia isquêmica (CI) é a principal causa de mortalidade em pacientes com Diabete Melito (DM) tipo 2. A doença coronariana é mais grave e extensa nestes pacientes. O excesso de mortalidade deve-se ao agrupamento de fatores de risco convencionais e a fatores especificamente relacionados ao DM. Os pacientes diabéticos apresentam também peculiaridades em relação às manifestações clínicas. A acurácia dos diversos métodos diagnósticos não invasivos utilizados para o diagnóstico de cardiopatia isquêmica não foi ainda suficientemente avaliada em estudos prospectivos de pacientes diabéticos. Os objetivos deste estudo foram analisar as manifestações clínicas e os testes diagnósticos não invasivos para a presença de cardiopatia isquêmica em pacientes com DM tipo 2; determinar as características clínicas e laboratoriais dos pacientes portadores de Cl e descrever os fatores de risco (como razão de chance) associados à presença de Cl de um modo geral e da forma assintomática. Foram estudados 120 pacientes ambulatoriais com DM tipo 2 (64 homens e 56 mulheres) com idades de 59 ± 8 anos e duração conhecida do DM de 11 ± 7 anos. Os pacientes foram submetidos a uma avaliação clínica para detectar Os objetivos deste estudo foram analisar as manifestações clínicas e os testes diagnósticos não invasivos para a presença de cardiopatia isquêmica em pacientes com DM tipo 2; determinar as características clínicas e laboratoriais dos pacientes portadores de Cl e descrever os fatores de risco (como razão de chance) associados à presença de Cl de um modo geral e da forma assintomática. Foram estudados 120 pacientes ambulatoriais com DM tipo 2 (64 homens e 56 mulheres) com idades de 59 ± 8 anos e duração conhecida do DM de 11 ± 7 anos. Os pacientes foram submetidos a uma avaliação clínica para detectar complicações crônicas e responderam ao questionário cardiovascular da Organização Mundial de Saúde para identificar a presença de angina do peito, infarto do miocárdio e claudicação intermitente. Foram realizados eletrocardiograma de repouso e cintilografia miocárdica com dipiridamol (técnica planar). A presença de cardiopatia isquêmica foi definida pelo questionário cardiovascular e/ou alterações eletrocardiográficas de acordo com o código Minnesota e/ou alterações na cintilografia miocárdica (isquemia ou necrose). A Cl foi diagnosticada em 53 (44%) dos pacientes. Nestes pacientes o questionário cardiovascular foi positivo em 24 (45%), as alterações do ECG em 28 (53%). A cintilografia miocárdica foi positiva em 30 (57%) e em 9 (17%) foi o único exame alterado. Portanto o questionário cardiovascular e o eletrocardiograma estabeleceram o diagnóstico de Cl em 83% dos casos. A comparação entre a cintilografia pelo método planar e SPECT foi realizada em vinte e três pacientes. Houve uma concordância diagnóstica em 83% dos casos. Os pacientes com Cl eram mais velhos (61 ± 7 vs. 58 ± 9 anos) com maior índice de massa corporal (28 ± 4 vs. 26± 5 kg/m2) e apresentavam níveis de pressão arterial sistólica (164 ± 23 vs. 152 ± 27 mm/Hg), de glicose plasmática em jejum (194 ± 77 vs. 167 ± 61 mg/dl) e de triglicerídeos (175 vs. 125 mg/dl) mais elevados. Os fatores de risco associados à presença de Cl, após ajuste pela análise de regressão logística foram a pressão arterial sistólica, níveis séricos de glicose e de triglicerídeos e a idade. Os pacientes com Cl apresentavam mais freqüentemente outras complicações macroangiopáticas. Vinte e nove pacientes (55%) com o diagnóstico de Cl não apresentavam nem haviam apresentado manifestações de desconforto precordial. Os fatores de risco associados à Cl assintomática, após análise de regressão logística, foram a presença de neuropatia autônoma e nefropatia e menor índice de massa corporal Em conclusão, a presença de Cl nesta amostra de pacientes diabéticos do tipo 2 foi estabelecida em 83% dos casos por história clínica e ECG padronizados. A cintilografia miocárdica apresentou uma resolução diagnóstica menor do que o esperado, provavelmente por fatores específicos relacionados ao diabete. A presença de Cl nestes pacientes foi significativamente associada com o aumento da pressão arterial sistólica, da idade, dos níveis de glicose e de triglicerídeos e do índice de massa corporal. A forma assintomática da Cl foi associada à presença de neuropatia autônoma e nefropatia diabéticas e menor índice de massa corporal. A análise de desfechos cardiovasculares definitivos nesta amostra de pacientes após um período de acompanhamento será importante para confirmar a acurácia dos critérios diagnósticos utilizados e dos fatores de risco associados.lschemic heart disease is the main cause of mortality in type 2 diabetic patients. Coronary artery disease (CAD) is more severe and extensive in these patients. The excess mortality rate is due to a clustering of conventional and diabetes-specific risk factors. The clinicai presentation of CAD in diabetic patients could be atypical in a significant proportion of patients. The significance of non-invasive methods commonly used to diagnose CAD in diabetic patients was not evaluated in prospective studies. The aims of this study were to analyze the clinicai manifestations and noninvasive diagnostic tests (ECG and myocardial scintigraphy) for the diagnosis of CAD; to establish the clinicai and laboratory characteristics of the patients with CAD and to describe the risk factors (as odds ratio) associated with CAD in general and with silent CAD. One-hundred and twenty type 2 diabetic outpatients (64 males, 56 females) with a mean age of 59 ± 8 years and known duration of diabetes of 11 ± 7 years. The patients undergone a clinicai evaluation to detect chronic complications and answered the World Health Organization Cardiovascular questionnaire to identify the presence of angina, myocardial infarction, and intermittent claudication. Rest ECG and dipyridamol myocardial scintigraphy (planar technique) were also performed. The diagnosis of CAD was established based on the questionnaire, and/or ECG alterations classified according Minnesota code and/or abnormalities (ischemia or necrosis) on myocardial scintigraphy. CAD was established in 53 (44%) of the patients. The presence of angina or previous infarct according to the cardiovascular questionnaire was identified in 24 (45%) patients and abnormalities of ECG in 30 (57%) patients. Myocardial scintigraphy was abnormal in 30 (57%) cases and it was the only abnormal test in 9 (17%). Therefore the cardiovascular questionnaire and ECG established the diagnosis of CAD in 83% of the patients. Planar and SPECT scintigraphy were compared in 23 patients and a diagnostic concordance rate of 83% was observed. Patients with CAD were older (61 ± 7 vs. 58± 9 years), had an increased body mass index (28 ± 4 vs. 26 ± 5 kglm\ and presented higher leveis of systolic blood pressure (164 ± 23 vs. 152 ± 27 mm/Hg), plasma glucose (194 ± 77 vs. 167 ± 61 mg/dl) and triglyceride leveis (175 vs. 125 mg/dl). Multiple logistic regression analysis confirmed that age, systolic blood pressure, plasma glucose and triglycerides leveis remained significantly associated to CAD. Patients with CAD presented also more frequently other macroangiopathic complications. In 29 (55%) patients with CAD there was no report of precordial discomfort. The risk factors associated to asymptomatic CAD after a multiple logistic regression analysis were autonomic neuropathy, nephropathy and body mass index . In conclusion, the diagnosis of CAD in this sample of type diabetic patients was based on the cardiovascular questionnaire and ECG abnormalities in 83% of the cases. Myocardial scintigraphy presented a diagnostic performance lower than expected, probably due to specific factors related to diabetes condition. CAD was significantly associated with increased leveis of systolic blood pressure, of plasma glucose leveis, triglycerides leveis and body mass index, and older age. Asymptomatic CAD was significantly associated with autonomic neuropathy and nephropathy and body mass index. Analysis of cardiovascular outcomes in this sample of type 2 diabetic patients after a follow-up period will be important to establish the accuracy of the diagnostic criteria employed and the associated risk factors

What does it take to detect entanglement with the human eye?

Tremendous progress has been realized in quantum optics for engineering and detecting the quantum properties of light. Today, photon pairs are routinely created in entangled states. Entanglement is revealed using single-photon detectors in which a single photon triggers an avalanche current. The resulting signal is then processed and stored in a computer. Here, we propose an approach to get rid of all the electronic devices between the photons and the experimentalist, i.e., to use the experimentalist’s eye to detect entanglement. We show in particular that the micro-entanglement that is produced by sending a single photon into a beam splitter can be detected with the eye using the magnifying glass of a displacement in phase space. The feasibility study convincingly demonstrates the possibility of realizing the first experiment where entanglement is observed with the eye.QID/Wehner GroupQuTec

High-fidelity Greenberger-Horne-Zeilinger state generation within nearby nodes

Generating entanglement in a distributed scenario is a fundamental task for implementing the quantum network of the future. We here report a protocol that uses only linear optics for generating Greenberger-Horne-Zeilinger states with high fidelities in a nearby node configuration. Moreover, we analytically show that the scheme is optimal for certain initial states in providing the highest success probability for sequential protocols. Finally, we give some estimates for the generation rate in a real scenario.QID/Wehner GroupQuTechQuantum Internet DivisionQuantum Information and Softwar

Challenging preconceptions about Bell tests with photon pairs

10.1103/PhysRevA.91.012107Physical Review A - AtomicMolecularand Optical Physics91