1,720,966 research outputs found
Hybrid photonic technologies for quantum information tasks
No full textIn the last thirty years, Quantum Information has become an established research field, providing a unique framework to harness the properties of inherently quantum systems to process and transmit information in ways that surpass the capabilities of classical information processing. It has been shown how quantum-based approaches find several practical applications, such as quantum computing, simulation, metrology, and communication. In this context, thanks to continuous developments of photonic technologies, photon-based platforms have established themselves as an excellent experimental testbed for the demonstration and implementation of a wide range of Quantum Information Processing tasks. Within this framework, the main goal of the present Ph.D. thesis is to employ the toolbox of photon-based Quantum Information processing - together with the capabilities offered by a set of state-of-the-art photonic technologies related to photon generation, manipulation, and detection - to devise experimental platforms suitable for the demonstration of photon-based Quantum Information protocols. In this perspective, this work focused on developing a hybrid photonic architecture tailored for multiphoton Quantum Information experiments. I designed and assembled such a platform and characterized its underlying elements: Quantum Dot sources, time-to-spatial demultiplexing setups, and universal reconfigurable integrated photonic interferometers. This thesis's experimental results have been focused on the context of the characterization of multiphoton interference effects and the implementation of photon-based computational protocols. First, I experimentally investigated fully optical schemes suitable for the generation of polarization-based and orbital angular momentum-based entangled photon pairs via single photons emitted consecutively by a QD source. Then, given that the emergence of quantum interference effects in multiphoton scenarios is at the core of the concept of linear optical computing, I developed and validated, on one side, semi-device-independent techniques for characterizing multiphoton indistinguishability. On the other, I investigated the behavior of multiphoton interference effects in scenarios featuring partial distinguishability, where seemingly counterintuitive phenomena can arise. The last part of this Ph.D. thesis will be focused on the experimental realization of photon-based protocols related to quantum computing applications. I provided an experimental implementation of a hybrid quantum-classical technique that finds, via variational techniques, optimal linear optical circuits implementing a quantum cloning machine of dual-rail encoded qubits. Then, I considered a recently proposed routine for the manipulation of quantum randomness - the quantum-to-quantum Bernoulli Factory. I experimentally validated an architecture based on polarization-based encoding implementing such a protocol, exploiting the demultiplexed QD source interfaced with a fully in-bulk and modular interferometric setup. Finally, I employed the hybrid photonic architecture at its full capability to investigate a proof-of-principle photonic implementation of a so-called Adaptive Boson Sampling scheme, an approach that goes beyond the standard Boson Sampling paradigm via the addition of measurement-based adaptivity. Overall, the results reported here highlight the versatility of a hybrid photonic approach and may open the path toward increasingly complex demonstrations of photon-based platforms for Quantum Information tasks
Teleportation of a genuine single-rail vacuum-one-photon qubit generated via a quantum dot source
No full textQuantum state teleportation represents a pillar of quantum information and a milestone on the roadmap towards quantum networks with a large number of nodes. Successful photonic demonstrations of this protocol have been carried out employing different qubit encodings. However, demonstrations in the Fock basis encoding are challenging, due to the impossibility of generating a coherent superposition of vacuum-one photon states on a single mode with linear optics. Indeed, previous realizations only allowed the teleportation of dual-rail entangled states, by exploiting ancillary electromagnetic modes. Here, instead, we enable the quantum teleportation of pure vacuum-one-photon qubits encoded in a single spatial mode, by exploiting coherent control of a resonantly excited semiconductor quantum dot in a micro-cavity. Within our setup, we can both teleport genuine single-rail vacuum-one-photon qubits and perform entanglement swapping. Our results may disclose new quantum information processing potentialities for this encoding, whose manipulation is achievable via quantum dot single-photon sources
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Generation and characterization of polarization-entangled states using quantum dot single-photon sources
Full text linkSingle-photon sources based on semiconductor quantum dots find several applications in quantum information processing due to their high single-photon indistinguishability, on-demand generation, and low multiphoton emission. In this context, the generation of entangled photons represents a challenging task with a possible solution relying on the interference in probabilistic gates of identical photons emitted at different pulses from the same source. In this work, we implement this approach via a simple and compact design that generates entangled photon pairs in the polarization degree of freedom. We operate the proposed platform with single photons produced through two different pumping schemes, the resonant excited one and the longitudinal-acoustic phonon-assisted configuration. We then characterize the produced entangled two-photon states by developing a complete model taking into account relevant experimental parameters, such as the second-order correlation function, Hong-Ou-Mandel visibility, multiphoton emission and pump laser filtering. Our source shows long-term stability and high quality of the generated entangled states, thus constituting a reliable building block for optical quantum technologies
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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