9,546 research outputs found

    Bilinear and quadratic Hamiltonians in two-mode cavity quantum electrodynamics

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    In this work we show how to engineer bilinear and quadratic Hamiltonians in cavity quantum electrodynamics (QED) through the interaction of a single driven two-level atom with cavity modes. The validity of the engineered Hamiltonians is numerically analyzed even considering the effects of both dissipative mechanisms, the cavity field and the atom. The present scheme can be used, in both optical and microwave regimes, for quantum state preparation, the implementation of quantum logical operations, and fundamental tests of quantum theory.Comment: 11 pages, 3 figure

    Nonadiabatic coherent evolution of two-level systems under spontaneous decay

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    In this paper we extend current perspectives in engineering reservoirs by producing a time-dependent master equation leading to a nonstationary superposition equilibrium state that can be nonadiabatically controlled by the system-reservoir parameters. Working with an ion trapped inside a nonindeal cavity we first engineer effective Hamiltonians that couple the electronic states of the ion with the cavity mode. Subsequently, two classes of decoherence-free evolution of the superposition of the ground and decaying excited levels are achieved: those with time-dependent azimuthal or polar angle. As an application, we generalise the purpose of an earlier study [Phys. Rev. Lett. 96, 150403 (2006)], showing how to observe the geometric phases acquired by the protected nonstationary states even under a nonadiabatic evolution.Comment: 5 pages, no figure

    Mapeamento de uso e cobertura da terra de uma bacia de drenagem no Bioma Mata Atlântica com uso de imagem de alta resolução.

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    A proteção da natureza não é um fenômeno exclusivo dos dias atuais. A preocupação com a preservação dos recursos naturais já se constituía em um desafio para as sociedades antigas. O desenvolvimento de técnicas de sensoriamento remoto e geoprocessamento contribuem sobremaneira com esse objetivo, tendo em vista a possibilidade de avaliações de uso e cobertura das terras nas mais diversas escalas de análise. O presente trabalho teve como objetivo mapear o uso e cobertura da terra de uma bacia de área de montanha no Rio de Janeiro, utilizando-se uma imagem de alta resolução do ano de 2010. Pretende-se, nesse trabalho, apresentar resultados referentes ao mapeamento no ano de 2010 e compará-lo com o mapeamento já realizado na área, no ano de 2004, e assim caracterizar as mudanças de uso e cobertura da terra na bacia.bitstream/item/141895/1/BPD-229-Mapeamento-Uso.pd

    Taxonomy and software architecture for real-time context-aware collaborative smart environments

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    The widespread of Internet of Things (IoT) and the price reduction and ubiquity of telecommunications has led to the emergence of smart environments where devices are becoming increasingly smarter and everything is connected and from which society aims to benefit. The data obtained from IoT is rapidly processed in various domains for the achievement of smart cities and societies. However, in many cases, applications are not contextualized by using data from outside the domain but are only contextualized using data from the domain itself, missing the opportunity for further contextualization. The lack of common criteria for the integration of data from different application domains is one of the main reasons that significantly hinders the integration of third-party data into real-time processing and decision-making systems and thus, the context awareness of developed applications. Although the use of several taxonomies and ontologies for context awareness in various application domains have been proposed, in many cases they are highly domain specific and/or difficult to integrate with other systems, which makes it challenging to facilitate data sharing between different systems and their processing to achieve enhanced context awareness. We aim to contribute to the addressing of these limitations through a reusable and extensible multi-domain taxonomy targeted to collaborative IoT and smart environments, which is also automatically integrated into a software architecture with real-time complex event processing technologies. The proposed solution has been illustrated through a case study and performance tests have been carried out in different computing capacity scenarios, showing its feasibility and usefulness
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