Ab initio transport results for strongly correlated fermions

Quantum transport of strongly correlated fermions is of central interest in condensed matter physics. Here, we present first-principle nonequilibrium Green functions results using $T$-matrix selfenergies for finite Hubbard clusters of dimension $1,2,3$. We compute the expansion dynamics following a potential quench and predict its dependence on the interaction strength and particle number. We discover a universal scaling, allowing an extrapolation to infinite-size systems, which shows excellent agreement with recent cold atom diffusion experiments [Schneider et al., Nat. Phys. 8, 213 (2012)]

Nonequilibrium Green Functions Simulations on the Next Level: Theoretical Advances and Applications to Finite Lattice Systems

This thesis is devoted to the description of correlated finite lattice systems under nonequilibrium conditions. In this context, the lack of small parameters in the corresponding standard many-body equations makes it difficult to construct suitable approximations for theoretical tools, which renders the computation of relevant observables numerically costly and impractical. At the same time, rigorous predictions for the ultrafast dynamics in correlated lattices are highly valuable for the understanding of many state-of-the-art experiments. The nonequilibrium Green functions (NEGF) technique is particularly well-suited to meet the challenging demands that come with the description of the nontrivial interplay between quantum correlations and nonequilibrium effects in excited lattice systems. However, in order to apply the approach on a practically relevant scale, several methodological improvements come to be indispensable. The present thesis contains these theoretical advances of the NEGF method, alongside with—thus accessible—applications to ultracold atoms in optical lattices and excited finite graphene nanostructures

Educação a distância no Brasil: caminhos, políticas e perspectivas

O artigo descreve os caminhos da Educação a Distância (EaD) no Brasil, em um cenário no qual esta modalidade de educação apresenta-se como uma alternativa para atender as necessidades de formação profissional em um país com grandes dimensões geográficas e sérias desigualdades regionais. Para tanto, serão apresentadas as políticas para uma EaD de qualidade, com o uso das tecnologias e a indicação de ações governamentais e institucionais que visam promover e garantir referenciais norteadores para esta modalidade educacional. Os desafios dentro de uma prática social para a EaD e os aspectos ideológicos e políticos são discutidos e contrapostos com algumas experiências já vivenciadas de EaD em iniciativas públicas brasileiras e na Universidade Estadual Paulista (Unesp). Diante das perspectivas apresentadas, as conclusões finais mostram que a EaD é uma modalidade educacional capaz de oferecer soluções para os problemas brasileiros desde que considerado o uso de uma abordagem que garanta a interação, o diálogo e a colaboração entre professores e alunos, o que são elementos que condicionam a natureza da aprendizagem e a construção do conhecimento.The article describes the Distance Education (EAD) ways, in Brazil, as an alternative form of education in a huge and unequal country, where Education problems have to be solved. The EaD policies will be submitted to a high quality work, using technology and, at the same time, indicating institutional and governmental actions to promote and ensure this modality of education. The challenges within a social practice to an EaD and the ideological and political aspects are discussed and opposed with some groups, in Brazil, particularly and emphatically in São Paulo State University (Unesp). Afterwards we can conclude that with EaD it is possible to find out solutions to many of our country problems using the dialogue, promoting the interaction and collaboration among teachers and students, who are the ones that will improve the knowledge and learning