Doped AB_2 Hubbard Chain: Spiral, Nagaoka and RVB States, Phase Separation and Luttinger Liquid Behavior

We present an extensive numerical study of the Hubbard model on the doped AB$_2$ chain, both in the weak coupling and the infinite-U limit. Due to the special unit cell topology, this system displays a rich variety of phases as function of hole doping ($\delta$) away from half-filling. Near half-filling, spiral states develop in the weak coupling regime, while Nagaoka itinerant ferromagnetism is observed in the infinite-U limit. For higher doping the system phase-separates before reaching a Mott insulating phase of short-range RVB states at $\delta=1/3$. Moreover, for $\delta>1/3$ we observe a crossover, which anticipates the Luttinger liquid behavior for $\delta > 2/3$.Comment: 11 pages, 13 figure

Magnetism and Electronic Correlations in Quasi-One-Dimensional Compounds

In this contribution on the celebration of the 80th birthday anniversary of Prof. Ricardo Ferreira, we present a brief survey on the magnetism of quasi-one-dimensional compounds. This has been a research area of intense activity particularly since the first experimental announcements of magnetism in organic and organometallic polymers in the mid 80s. We review experimental and theoretical achievements on the field, featuring chain systems of correlated electrons in a special AB2 unit cell structure present in inorganic and organic compounds

Decoherence, pointer engineering and quantum state protection

We present a proposal for protecting states against decoherence, based on the engineering of pointer states. We apply this procedure to the vibrational motion of a trapped ion, and show how to protect qubits, squeezed states, approximate phase eigenstates and superpositions of coherent states.Comment: 1 figur

Cultivos sucessivos de milho em várzea.

Visando obter informações sobre formas de cultivares de milho em várzeas, capazes de manter em uma mesma área elevadas produtividades por um período maior que o verificado atualmente, estao sendo avaliados cultivos sucessivos dessa espécie, através de ações de pesquisa executadas em várzea úmida as margens do rio Mazagão, município de Mazagão, AP.bitstream/item/65117/1/AP-1997-cultivos-sucessivos-milho.pd

Seleção de clones promissores de cupuaçuzeiros para a implantação de pomares comerciais no Estado do Amapá.

bitstream/item/145486/1/CPAF-AP-2015-BPD-91-Cupuacu-v3-1.pd

Manejo de doenças do mamoeiro.

O mamoeiro é afetado por um grande número de doenças. As de maior importância econômica são citadas a seguir: Viroses ? As viroses constituem o maior entrave à implantação da cultura do mamoeiro, por causa da dificuldade do seu controle e da necessidade de migração que elas impõem à essa cultura. As três mais importantes são: o vírus vírus-da-mancha-anelar do- mamoeiro, no Brasil conhecido como o mosaico-do-mamoeiro; o vírus-da-meleira; e o vírus-do-amarelo mamoeiro; vírus amarelo-letal.Curso

Seleção de matrizes promissoras de buriti (Mauritia flexuosa l.) no Amapá tendo em vista a produção de biocombustível.

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Generalized partition functions and interpolating statistics

We show that the assumption of quasiperiodic boundary conditions (those that interpolate continuously periodic and antiperiodic conditions) in order to compute partition functions of relativistic particles in 2+1 space-time can be related with anyonic physics. In particular, in the low temperature limit, our result leads to the well known second virial coefficient for anyons. Besides, we also obtain the high temperature limit as well as the full temperature dependence of this coefficient.Comment: 12 pages, Latex, updated and enlarged versio