The double Caldeira-Leggett model: Derivation and solutions of the master equations, reservoir-induced interactions and decoherence

In this paper we analyze the double Caldeira-Leggett model: the path integral approach to two interacting dissipative harmonic oscillators. Assuming a general form of the interaction between the oscillators, we consider two different situations: i) when each oscillator is coupled to its own reservoir, and ii) when both oscillators are coupled to a common reservoir. After deriving and solving the master equation for each case, we analyze the decoherence process of particular entanglements in the positional space of both oscillators. To analyze the decoherence mechanism we have derived a general decay function for the off-diagonal peaks of the density matrix, which applies both to a common and separate reservoirs. We have also identified the expected interaction between the two dissipative oscillators induced by their common reservoir. Such reservoir-induced interaction, which gives rise to interesting collective damping effects, such as the emergence of relaxation- and decoherence-free subspaces, is shown to be blurred by the high-temperature regime considered in this study. However, we find that different interactions between the dissipative oscillators, described by rotating or counter-rotating terms, result in different decay rates for the interference terms of the density matrix.Comment: 42 pages, 7 figures, new discussion added, typos adde

Performance of CAM based Safety Applications using ITS-G5A MAC in High Dense Scenarios

ETSI ITS-G5 is the current vehicle-to-vehicle communication technology in Europe, which will be standardized by ETSI TC ITS. It is based on IEEE 802.11p and therefore uses a CSMA/CA scheme for Media Access Control (MAC). In this paper we analyze the performance of CAM based safety applications using the ETSI ITS-G5 MAC technology in a challenging scenario with respect to MAC issues: A suitable freeway segment with 6 lanes in each direction. The freeway scenario is thoroughly modeled and implemented in the well known ns-3 simulation environment. Based on this model, the paper shows the performance of CAM based safety applications under MAC challenging conditions. Therefore we provide a set of simulation results resting upon a particular performance metric which incorporates the key requirements of safety applications. Finally we analyze two concrete example scenarios to make a point how reliable CAM based safety applications are in high dense traffic scenarios

Relaxation- and Decoherence-free subspaces in networks of weakly and strongly coupled resonators

We consider a network of interacting resonators and analyze the physical ingredients that enable the emergence of relaxation-free and decoherence-free subspaces. We investigate two different situations: i) when the whole network interacts with a common reservoir and ii) when each resonator, strongly coupled to each other, interacts with its own reservoir. Our main result is that both subspaces are generated when all the resonators couple with the same group of reservoir modes, thus building up a correlation (among these modes), which has the potential to shield particular network states against relaxation and/or decoherence.Comment: 5 page

An exact master equation for the system-reservoir dynamics under the strong coupling regime and non-Markovian dynamics

In this paper we present a method to derive an exact master equation for a bosonic system coupled to a set of other bosonic systems, which plays the role of the reservoir, under the strong coupling regime, i.e., without resorting to either the rotating-wave or secular approximations. Working with phase-space distribution functions, we verify that the dynamics are separated in the evolution of its center, which follows classical mechanics, and its shape, which becomes distorted. This is the generalization of a result by Glauber, who stated that coherent states remain coherent under certain circumstances, specifically when the rotating-wave approximation and a zero-temperature reservoir are used. We show that the counter-rotating terms generate fluctuations that distort the vacuum state, much the same as thermal fluctuations.Finally, we discuss conditions for non-Markovian dynamics

(English-Portuguese and Portuguese-English). Abstracts for Heritage—Journal of History, Heritage and Culture; editorial review for scientific journals, Marine Studies and Engineering Assets; revision of the English version of the websites of Ponte Editora

Within the scope of the Master's Degree in Linguistics: Societies and Cultures (2nd Cycle), the student carried out a Master's internship with a report at Ponte Editora, an online platform based in Startup Madeira, Penteada Campus. By implementing the theoretical knowledge obtained in the master's degree, the internship mainly consisted in translating and revising scientific texts. The objectives of the internship were: to contextualize and delimit the areas of activity of the company Ponte Editora and the audience to whom its services are intended; translate from English to Portuguese and Portuguese to English abstracts of scientific articles for the journal Heritage—Journal of History, Heritage and Culture; review and edit texts for the scientific journals Marine Studies and Engineering Assets; review the English version of the Ponte Editora's websites; standardize the layout of the websites of the new scientific journals to conform with the existing one of the journal Heritage. Another important activity involved translating abstracts of scientific papers to be published in the special issue of the journal Heritage. For the editorial review activity of the academic journals Marine Studies and Engineering Assets, redefining the menus of the websites, reorganizing their contents according to the journal Heritage. The internship activities included reviewing and editing the English version of the websites, comparing the texts of various magazines stored at the platform and improving the institutional website of the platform Ponte Editora. Additionally the student’s Erasmus experience will be included since it enriched her experience on the subjects already mentioned.No âmbito do Mestrado em Linguística: Sociedades e Culturas (2º Ciclo), a estudante realizou um estágio de mestrado com relatório na Ponte Editora, uma plataforma online sediada na Startup Madeira, Campus da Penteada. Implementando os conhecimentos teóricos obtidos no mestrado, o estágio consistiu essencialmente na tradução e revisão de textos científicos. Os objetivos do estágio foram: contextualizar e delimitar as áreas de atuação da empresa Ponte Editora e o público a que se destinam os seus serviços; traduzir de inglês para português e de português para inglês resumos de artigos científicos para a revista Herança-Jornal de História, Herança e Cultura; rever e editar textos para as revistas científicas de Estudos do Mar (REM) e de Ativos de Engenharia (RAE); rever a versão em inglês dos sites da Ponte Editora; uniformizar o layout dos sites das novas revistas científicas para que estejam em conformidade com o existente para a revista Herança. Outra atividade importante foi a tradução de resumos de artigos científicos a publicar no número especial da mesma revista. As atividades do estágio incluíram a revisão e edição da versão inglesa dos sites, a comparação dos textos de várias revistas armazenadas na plataforma e a melhoria do site institucional da plataforma Ponte Editora. Adicionalmente, será incluída a experiência de formação Erasmus da estudante, uma vez que enriqueceu as suas competências nos temas referidos