Experimental realization of a measurement conditional unitary operation at single photon level and application to detector characterization

Our last experimental results on the realization of a measurement-conditional unitary operation at single photon level are presented. This gate operates by rotating by $90^o$ the polarization of a photon produced by means of Type-II Parametric Down Conversion conditional to a polarization measurement on the correlated photon. We then propose a new scheme for measuring the quantum efficiency of a single photon detection apparatus by using this set-up. We present experimental results obtained with this scheme compared with {\it traditional} biphoton calibration. Our results show the interesting potentiality of the suggested scheme.Comment: to appear in Proc. of SPIE meeting, Denver august 200

Meaningful Meaninglessness: Albert Camus\u27 Presentation of Absurdism as a Foundation for Goodness

In 1957, Albert Camus won the Nobel Prize for Literature. By that time he had written such magnificently important works such as Caligula (1938), The Stranger (1942), The Myth of Sisyphus (1942), The Plague (1947), The Rebel (1951), and The Fall (1956). Camus was a proponent of Absurdism, a philosophy that realizes the workings of the world are inherently meaningless and indifferent to the human struggle to create meaning. Absurdism, however, is not a nihilistic philosophy. In The Myth of Sisyphus, The Rebel, and Caligula, Camus offers a foundation of optimism and morality

Comparação entre o conteúdo de fenólicos e capacidade antioxidante de sementes

Frequent nut intake is associated with protective effects against cardiovascular diseases. In addition to the generally high contents of unsaturated fatty acids, polyphenol compounds seem to be also implicated in health promoting effects of nuts due to their antioxidant properties. In this way, eleven different kinds of nuts, including pinhao seeds (Araucaria angustifolia) and Brazil nuts (Bertholletia excelsa), typical of Brazil, were analyzed for the content of phenol compounds, including the potent anti-mutagenic and anti-cancer ellagic acid, and antioxidant capacity of methanolic extracts. The antioxidant capacity varied a hundred times among the different nuts, from 1.2 to 120 mg of Trolox equivalents.100 g-1 (FW). Total ellagic acid was determined after acid hydrolysis of ellagitannins and ellagic acid glycosides, and it was detected in only 3 of the 11 samples. The content of free and total ellagic acid in nuts varied from 0.37 to 41 and from 149 (chestnuts) to 823 (walnuts) mg.100 g-1 (FW), respectively. Among nuts, samples with the highest contents of ellagic acid (walnuts and pecans) also presented the highest total phenol contents and DPPH radical scavenging capacities. Pinhao seeds and Brazil nuts did not present significant amounts of phenols nor antioxidant capacity.O consumo frequente de nozes está associado a efeitos protetores contra doenças cardiovasculares. Além do alto teor de ácidos graxos insaturados, os compostos polifenólicos também parecem implicados nos efeitos promotores da saúde devido a suas propriedades antioxidantes. Desta forma, onze tipos de nozes/sementes, incluindo pinhão (Araucaria angustifolia) e castanha-do-pará (Bertholletia excelsa), típicos do Brasil, foram analisados em relação ao seu conteúdo de fenólicos, incluindo ácido elágico, tido como potente antimutagênico e anticancerígeno, e capacidade antioxidante dos extratos metanólicos. A capacidade antioxidante variou cem vezes entre as diferentes amostras, de 1,2 a 120 mg equivalentes de Trolox.100 g-1 (b.u.). O ácido elágico total, determinado após hidrólise ácida dos elagitaninos e glicosídeos de ácido elágico, foi detectado em apenas 3 amostras. Os conteúdos de ácido elágico livre e total variaram de 0,37 a 41 e de 149 (castanha portuguesa) a 823 (nozes) mg.100 g-1 (b.u.), respectivamente. As amostras com os maiores teores de ácido elágico (nozes e pecans) também apresentaram os conteúdos de fenólicos totais e a capacidade de sequestro do radical DPPH mais elevados. O pinhão e a castanha-do-pará não apresentaram quantidades significativas de fenólicos nem elevada capacidade antioxidante.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

The quantum-classical transition in thermally seeded parametric downconversion

We address the pair of conjugated field modes obtained from parametric-downconversion as a convenient system to analyze the quantum-classical transition in the continuous variable regime. We explicitly evaluate intensity correlations, negativity and entanglement for the system in a thermal state and show that a hierarchy of nonclassicality thresholds naturally emerges in terms of thermal and downconversion photon number. We show that the transition from quantum to classical regime may be tuned by controlling the intensities of the seeds and detected by intensity measurements. Besides, we show that the thresholds are not affected by losses, which only modify the amount of nonclassicality. The multimode case is also analyzed in some detail.Comment: 12 pages, 3 figure

Detection of multimode spatial correlation in PDC and application to the absolute calibration of a CCD camera

We propose and demonstrate experimentally a new method based on the spatial entanglement for the absolute calibration of analog detector. The idea consists on measuring the sub-shot-noise intensity correlation between two branches of parametric down conversion, containing many pairwise correlated spatial modes. We calibrate a scientific CCD camera and a preliminary evaluation of the statistical uncertainty indicates the metrological interest of the method