1,721,112 research outputs found
From q-plates to the photonic gear: tailoring the rotational properties of light
No full textThe rotational properties of a light beam are controlled by its spin and orbital angular momentum (SAM and OAM). The q-plate, a liquid crystal device that can give rise to a coupling of these two quantities, was introduced a few years ago, leading to several applications in classical and quantum photonics. Very recently, in particular, a specific kind of q-plate was used to generate rotational-invariant states of single photons, which were then employed for performing a demonstration of quantum key distribution without the need for establishing a common reference frame between the transmitting and the receiving units. This result may find applications in future satellite-based quantum communication. By a similar approach, photonic states having a strongly enhanced rotational sensitivity, as opposed to rotational invariance, can be generated by using q-plates with very high topological charge. Photons in these states can be obtained starting from light having a uniform linear polarization and, after a physical rotation, can be converted back into light having uniformly linear polarization. As a result, one obtains linearly polarized light whose polarization plane rotates by an angle that is proportional to the angle of physical rotation between the generation and detection stages, with a very large proportionality constant. This effect of rotational amplification, which we named "photonic gear", leads to a sort of "super-resolved Malus' law", potentially useful for measuring mechanical angles with very high precision
Quantum multiplexing in single photons
No full textAn optical system transfers quantum information from two photons to a single photo
Genetic algorithms to learn an unknown linear transformation
No full textIntegrated photonics enabled the capability to implement complex interferometers with a large number of modes. The applications of this experimental toolbox can be found in different quantum information tasks, including quantum walks and simulation [1], quantum metrology [2], up to the implementation of Boson Sampling [3-6], one of the most promising candidates to reach experimentally the regime where a quantum device solves a computational problem faster than its classical counterpart. Both from a fundamental aspect and for characterization purposes, it becomes crucial to identify tools allowing to learn the action of an unknown transformation
AN INTEGRATED OPTICS LOGIC GATE FOR POLARIZATION- ENCODED QUANTUM QUBITS AND A METHOD FOR THE PRODUCTION AND USE THEREOF
No full textEngineering of photonic orbital angular momentum quantum states for quantum information processing2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC)
No full textAmong all degrees of freedom offered by single photons, the orbital angular momentum (OAM) has a great potential in the quantum information field, as it provides a natural choice for implementing single-photon qudits, the units of quantum information in a higher dimensional space. This can be an important practical advantage, as it enables higher security in quantum cryptographic protocols, as well as implications in fundamental quantum mechanics theory. Moreover, the combined use of different degrees of freedom of a photon, such as OAM and spin, enables the implementation of entirely new quantum tasks. © 2011 IEEE
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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