Magnetism in SQUIDs at Millikelvin Temperatures

We have characterized the temperature dependence of the flux threading dc SQUIDs cooled to millikelvin temperatures. The flux increases as 1/T as temperature is lowered; moreover, the flux change is proportional to the density of trapped vortices. The data is compatible with the thermal polarization of surface spins in the trapped fields of the vortices. In the absence of trapped flux, we observe evidence of spin-glass freezing at low temperature. These results suggest an explanation for the "universal" 1/f flux noise in SQUIDs and superconducting qubits.Comment: 4 pages, 4 figure

Entanglement detection for electrons via witness operators

We discuss an implementation of the entanglement witness, a method to detect entanglement with few local measurements, in systems where entangled electrons are generated both in the spin and orbital degrees of freedom. We address the efficiency of this method in various setups, including two different particle-hole entanglement structures, and we demonstrate that it can also be used to infer information on the possible dephasing afflicting the devices.Comment: 12 pages, 5 figures; published versio

Marcadores moleculares para análise genética de germoplasma de pereira: uso na organização dos recursos genéticos e no melhoramento genético.

O objetivo deste estudo foi o de ajustar as metodologias científicas para a obtenção de marcadores microssatélites e RAPD para análise genética do germoplasma conservado em coleções de pera, visando à organização dos recursos genéticos da espécie do Brasil e ao apoio de atividades de melhoramento genético.bitstream/item/73908/1/Circular-Tecnica-93-online.pd

Construction of a synthetic infectious cDNA clone of Grapevine Algerian latent virus (GALV-Nf) and its biological activity in Nicotiana benthamiana and grapevine plants

Background: Grapevine Algerian latent virus (GALV) is a tombusvirus first isolated in 1989 from an Algerian grapevine (Vitis spp.) plant and more recently from water samples and commercial nipplefruit and statice plants. No further reports of natural GALV infections in grapevine have been published in the last two decades, and artificial inoculations of grapevine plants have not been reported. We developed and tested a synthetic GALV construct for the inoculation of Nicotiana benthamiana plants and different grapevine genotypes to investigate the ability of this virus to infect and spread systemically in different hosts. Methods: We carried out a phylogenetic analysis of all known GALV sequences and an epidemiological survey of grapevine samples to detect the virus. A GALV-Nf clone under the control of the T7 promoter was chemically synthesized based on the full-length sequence of the nipplefruit isolate GALV-Nf, the only available sequence at the time the project was conceived, and the infectious transcripts were tested in N. benthamiana plants. A GALV-Nf-based binary vector was then developed for the agroinoculation of N. benthamiana and grapevine plants. Infections were confirmed by serological and molecular analysis and the resulting ultrastructural changes were investigated in both species. Results: Sequence analysis showed that the GALV coat protein is highly conserved among diverse isolates. The first epidemiological survey of cDNAs collected from 152 grapevine plants with virus-like symptoms did not reveal the presence of GALV in any of the samples. The agroinoculation of N. benthamiana and grapevine plants with the GALV-Nf binary vector promoted efficient infections, as revealed by serological and molecular analysis. The GALV-Nf infection of grapevine plants was characterized in more detail by inoculating different cultivars, revealing distinct patterns of symptom development. Ultrastructural changes induced by GALV-Nf in N. benthamiana were similar to those induced by tombusviruses in other hosts, but the cytopathological alterations in grapevine plants were less severe. Conclusions: This is the first report describing the development of a synthetic GALV-Nf cDNA clone, its artificial transmission to grapevine plants and the resulting symptoms and cytopathological alterations

Índices de emissão de ramos em pereiras.

A elaboração de escalas de emissão de ramos em pereiras objetiva classificar os genótipos quanto a seu hábito de crescimento, as quis serão úteis para compor o índice de vigor de plantas e para a seleção de genitores em programas de melhoramento genético. Para isso, foram desenvolvidas duas escalas: a primeira, para avaliar a quantidade de emissão de ramos secundários, ou seja, os ramos originados do tronco principal da planta, composta por três classes e com notas variando entre 1 e 5, contendo desenhos e exemplos de genótipos; a segunda, para avaliar o tipo e a quantidade de ramos terciários e quaternários emitidos a partir dos ramos secundários, sendo ela composta também por três classes e notas variando de 1 a 5. Utilizando as duas tabelas, foram avaliadas duas (em alguns casos somente uma) plantas/genótipo do Banco de Germoplasma de Pereira existente na Estação Experimental de Caçador, em Caçador, SC, no ano agrícola 2012/13. As plantas ficaram sem poda e condução durante 2 anos. Exemplos de genótipos com menor emissão de ramos secundários foram os cvs. Kousui, Kikusui, Nijisseiki, Beurre d?Anjou e Doyenne du Comice; e com maior emissão os cvs. Le Conte e Md. Siebold. Quanto à menor emissão de ramos terciários e quaternários, destacaram-se os cvs. Rugosa e Md. Siebold; e com maior emissão os cvs. Feliz e Choujuurou. As escalas foram eficientes na separação dos genótipos

Classes de vigor de plantas de genótipos de pereira.

O índice de vigor de pereiras pode ser utilizado como referência em trabalhos de melhoramento genético para a seleção de genitores e também como indicativo de manejo de plantas em pomares comerciais. Para isso, foi gerado um índice de vigor utilizando informações de emissão de ramos secundários (originados do tronco principal da planta), de ramos terciários e quaternários (gerados respectivamente dos ramos secundários e terciários), além da medida da altura da planta

Entanglement in Mesoscopic Structures: Role of Projection

We present a theoretical analysis of the appearance of entanglement in non-interacting mesoscopic structures. Our setup involves two oppositely polarized sources injecting electrons of opposite spin into the two incoming leads. The mixing of these polarized streams in an ideal four-channel beam splitter produces two outgoing streams with particular tunable correlations. A Bell inequality test involving cross-correlated spin-currents in opposite leads signals the presence of spin-entanglement between particles propagating in different leads. We identify the role of fermionic statistics and projective measurement in the generation of these spin-entangled electrons.Comment: 5 pages, 1 figur

Decoherence in rf SQUID Qubits

We report measurements of coherence times of an rf SQUID qubit using pulsed microwaves and rapid flux pulses. The modified rf SQUID, described by an double-well potential, has independent, in situ, controls for the tilt and barrier height of the potential. The decay of coherent oscillations is dominated by the lifetime of the excited state and low frequency flux noise and is consistent with independent measurement of these quantities obtained by microwave spectroscopy, resonant tunneling between fluxoid wells and decay of the excited state. The oscillation's waveform is compared to analytical results obtained for finite decay rates and detuning and averaged over low frequency flux noise.Comment: 24 pages, 13 figures, submitted to the journal Quantum Information Processin

Perturbative Formulation and Non-adiabatic Corrections in Adiabatic Quantum Computing Schemes

Adiabatic limit is the presumption of the adiabatic geometric quantum computation and of the adiabatic quantum algorithm. But in reality, the variation speed of the Hamiltonian is finite. Here we develop a general formulation of adiabatic quantum computing, which accurately describes the evolution of the quantum state in a perturbative way, in which the adiabatic limit is the zeroth-order approximation. As an application of this formulation, non-adiabatic correction or error is estimated for several physical implementations of the adiabatic geometric gates. A quantum computing process consisting of many adiabatic gate operations is considered, for which the total non-adiabatic error is found to be about the sum of those of all the gates. This is a useful constraint on the computational power. The formalism is also briefly applied to the adiabatic quantum algorithm.Comment: 5 pages, revtex. some references adde

Quantum information processing with superconducting qubits in a microwave field

We investigate the quantum dynamics of a Cooper-pair box with a superconducting loop in the presence of a nonclassical microwave field. We demonstrate the existence of Rabi oscillations for both single- and multi-photon processes and, moreover, we propose a new quantum computing scheme (including one-bit and conditional two-bit gates) based on Josephson qubits coupled through microwaves.Comment: 7 pages, 1 figur