1,721,062 research outputs found
Nonclassicality detection from few Fock-state probabilities
Full text linkWe devise a new class of criteria to certify the nonclassicality of photon-
and phonon-number statistics. Our criteria extend and strengthen the broadly
used Klyshko's criteria, which require knowledge of only a finite set of
Fock-state probabilities. This makes the criteria well-suited to experimental
implementation in realistic conditions. Moreover, we prove the completeness of
our method in some scenarios, showing that, when only two or three Fock-state
probabilities are known, it detects all finite distributions incompatible with
classical states. In particular, we show that our criteria detect a broad class
of noisy Fock states as nonclassical, even when Klyshko's do not. The method is
directly applicable to trapped-ion, superconducting circuits, and optical and
optomechanical experiments with photon-number resolving detectors. This work
represents a significant milestone towards a complete characterisation of the
nonclassicality accessible from limited knowledge of the Fock-state
probabilities.Comment: 22 pages, 19 figures; comments welcom
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Entanglement localization after coupling to an incoherent noisy system
No full textWe report the experimental realization of entanglement localization which restores the polarization entanglement completely redirected after a linear coupling with incoherent and noisy surrounding photon. The method based only on measurements of the surrounding photon after the coupling and on postselection can localize the entanglement back to original systems for any linear coupling
Complete analysis of measurement-induced entanglement localization on a three-photon system
No full textWe discuss both theoretically and experimentally elementary two-photon polarization entanglement localization after break of entanglement caused by linear coupling of environmental photon with one of the system photons. The localization of entanglement is based on simple polarization measurement of the surrounding photon after the coupling. We demonstrate that nonzero entanglement can be localized back irrespectively to the distinguishability of coupled photons. Further, it can be increased by local single-copy polarization filters up to an amount violating Bell inequalities. The present technique allows restoration of entanglement in those cases, when the entanglement distillation produces no entanglement from the coupling
Experimental entanglement restoration on noisy channels by measuring environment
No full textIn the last years, different procedures have been developed in order to recover entanglement after propagation over a noisy channel. However, above a certain amount of noise, entanglement is completely lost. In this case the channel is called "entanglement-breaking" and any multi-copy distillation methods cannot help to reveal even a bit of entanglement. We report the experimental realization of a new protocol which restores entanglement from a single photon entanglement-breaking channel by measuring the information leaking out into the environment. Such restoration entanglement procedure provides new elements to overcome decoherence effects, a subject of renowed interest in quantum communication in the last decade. © 2009 World Scientific Publishing Company
Variations on the Author
Full text link“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
Full text linkWe 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
Sequential quantum measurements on entangled states2011 Conference on Lasers and Electro-Optics Europe and 12th European Quantum Electronics Conference (CLEO EUROPE/EQEC)
No full textQuantum measurement is a nontrivial physical process connecting the quantum and classical worlds. However in contrast to classical measurement, any quantum detection process unavoidably introduces decoherence in the quantum system, thus leading to a detrimental effect which establish a bound on the knowledge, i.e. the information, extractable from the system. In order to avoid such problem, a partial measurement approach can be adopted, whose aim is to extract only a partial amount of information from the quantum system at cost of limited decoherence induced [1]. In general, this partial measurement consists from two steps: coupling of measured system to an available meter and projective measurement on the meter. The aim of the work is to investigate a non-demolishing measurement strategy which allows to maximize the amount of information extracted from an entangled quantum state, given a certain amount of induced decoherence on the whole system. The protocol can be applied to a single measurement step, as well as extended to a number N of sequential measurements. Furthermore we demonstrate that by implementing a sequence of non-demolishing measurement on the state, it is still possible to achieve a strategy which leads to an optimal trade off between knowledge and decoherence induced. © 2011 IEEE
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