Open Quantum Systems
Mostrando 1-12 de 23 artigos, teses e dissertações.
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1. Termalização e correlações quânticas nos contextos de sistemas quânticos abertos e cadeias de spins
In this thesis, we study the behavior of Quantum Discord in the contexts of open quantum systems and spin chains. Furthermore, we investigate the thermalization process of a spin chain due to interaction with the environment. First, we present a review on the concept of quantum correlation, beginning with the first ideas on non-locality, and leading to the m
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 11/01/2013
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2. Entre mecánica cuántica y estructuras químicas: ¿a qué refiere la química cuántica?
The aim of this article is to address the question of the ontology of quantum chemistry. To this end we will focus on the concept of chemical bond, from the perspective of the two approaches by means of which the Schrödinger equation is applied to molecular chemical systems: the Theory of Valence Bond (VB) and the Theory of Molecular Orbital (MO). On the ba
Sci. stud.. Publicado em: 2012
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3. Computação quântica baseada em medidas projetivas em sistemas quânticos abertos / Measurement-based quantum computation in open quantum systems
Usamos um modelo exatamente solúvel para calcular a dinâmica da fidelidade de uma computação baseada em medidas projetivas cujo sistema interage com um meio ambiente comum que insere erros de fase. Mostramos que a fidelidade do estado de Cluster canônico oscila como função do tempo e, como consequência, a computação quântica baseada em medidas pro
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 20/06/2011
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4. Redes de osciladores dissipativos : o modelo duplicado de Caldeira-Leggett, transferência quase-perfeita de estados e recoerência
In this work we treat firstly what we call the double Caldeira-Leggett model, which consists on the approach to the dynamics of two dissipative harmonic oscillators via Feynman-Vernon theory. We derived and solved the associated master equations in two different situations where i) each oscillator is coupled to its own reservoir and ii) both oscillators are
Publicado em: 2010
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5. Classical and quantum correlations under decoherence / Correlações clássicas e quânticas sob decoerência
Recently, in the context of discrete variables, the existence of quantum correlations that are more general than entanglement was identified. We may conjecture that these correlations are a very important resource in quantum information science and in some areas of physics. However, this fragile resource is quickly destroyed by the decoherence process. In th
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 26/08/2009
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6. Nonadditive entropy and nonextensive statistical mechanics -an overview after 20 years
Statistical mechanics constitutes one of the pillars of contemporary physics. Recognized as such - together with mechanics (classical, quantum, relativistic), electromagnetism and thermodynamics -, it is one of the mandatory theories studied at virtually all the intermediate-and advanced-level courses of physics around the world. As it normally happens with
Brazilian Journal of Physics. Publicado em: 2009-08
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7. Entangled Brownian particles / Particulas Brownianas emaranhadas
This work consists in a study of entanglement in open quantum systems, within the brownian particles model. The interest comes from the possibility of understanding the mechanisms that lead the environment to create or to keep entanglement between quantum systems and not only make them lose energy or coherence. We start by making a review of the meaning of e
Publicado em: 2009
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8. Extended Bell´s Be-ables and Atenuattion × Amplification Competition. / Extensão dos Be-ables de Bell e Competição Atenuação x Amplificação
In the first part of this work we employ the Itô stochastic equation to extend Bells be-able interpretation of quantum mechanics to encompass dissipation, decoherence and quantum-to-classical transition through quantum trajectories. For a particular choice of the source of stochasticity, the one leading to a dissipative Lindblad type correction to the Hamil
Publicado em: 2009
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9. O efeito Casimir dinâmico e decoerência
In this thesis we first demonstrate that the inevitable action of the environment can be substantially weakened when considering appropriate nonstationary quantum systems. Beyond protecting quantum states against decoherence, an oscillating frequency can be engineered to make the system-reservoir coupling almost negligible. Differently from the program for e
Publicado em: 2008
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10. Engenharia de interações e de reservatórios
Nesta tese, apresentamos primeiramente um protocolo para a construção de interações efetivas entre dois modos de uma cavidade, através de um átomo de dois níveis sob a ação de campos clássicos. hamiltonianos bilineares associados à processos de conversões paramétricas ascendente e descendente de frequências foram obtidos, bem como hamiltonianos
Publicado em: 2008
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11. Vacancies in carbon nanotubes: electronic, structural and transport properties / Vacâncias em nanotubos de carbono: propriedades eletrônicas, estruturais e de transporte
The main purpose of this dissertation is the study of the electronic and structural properties in the presence of different types of vacancies, in one of the most promising materials for nanoelectronics, carbon nanotubes. The defects studied in this work are monovacancy and multivacancies in (5, 5) armchair carbon nanotubes. For that purpose perform quantum
Publicado em: 2008
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12. The inductive coupling with On-Chip coils / O acoplamento indutivo com bobinas On-Chip
The quantum Hall effect (QHE) remains the target of an immense research effort twenty six years after its discovery. In fact this phenomenon has been a source of fundamental questions. Among the open problems in the field is the spatial distribution of the electric current in the quantum Hall effect. This question has been in debate since its discovery. Some
Publicado em: 2007