Non-additivity of decoherence rates in superconducting qubits

We show that the relaxation and decoherence rates 1/T_1 and 1/T_2 of a qubit coupled to several noise sources are in general not additive, i.e., that the total rates are not the sums of the rates due to each individual noise source. To demonstrate this, we calculate the relaxation and pure dephasing rates 1/T_1 and 1/T_\phi of a superconducting (SC) flux qubit in the Born-Markov approximation in the presence of several circuit impedances Z_i using network graph theory and determine their deviation from additivity (the mixing term). We find that there is no mixing term in 1/T_\phi and that the mixing terms in 1/T_1 and 1/T_2 can be positive or negative, leading to reduced or enhanced relaxation and decoherence times T_1 and T_2. The mixing term due to the circuit inductance L at the qubit transition frequency \omega_{01} is generally of second order in \omega_{01}L/Z_i, but of third order if all impedances Z_i are pure resistances. We calculate T_{1,2} for an example of a SC flux qubit coupled to two impedances.Comment: 5 pages, 2 figure

RPA approach to rotational symmetry restoration in a three-level Lipkin model

We study an extended Lipkin-Meshkov-Glick model that permits a transition to a deformed phase with a broken continuous symmetry. Unlike simpler models, one sees a persistent zero-frequency Goldstone mode past the transition point into the deformed phase. We found that the RPA formula for the correlation energy provides a useful correction to the Hartree-Fock energy when the number of particle N satisfies N > 3, and becomes accurate for large N. We conclude that the RPA correlation energy formula offers a promising way to improve the Hartree-Fock energy in a systematic theory of nuclear binding energies.Comment: RevTex, 11 pages, 3 postscript figure

Cartilha para o produtor de leite de Rondônia. Vol. I: Instalações, sanidade animal e a Instrução Normativa 51.

Esta cartilha destina-se ao produtor de leite e tem como principal objetivo trazer um conjunto de orientações técnicas, as quais poderão ser utilizadas na propriedade visando o desenvolvimento da atividade leiteira, considerando também as imposições da Instrução Normativa 51, que deverá ser atendida a partir de julho de 2007 pelos produtores de leite das regiões Norte e Nordeste do país.bitstream/item/24649/1/doc100-cartilhaprodutorleite.pd

Efeitos de gramíneas forrageiras sobre a porosidade do solo em Uruará (Transamazônica), Pará.

Cópia de CD-ROM

Porotaxia em larva de carrapatos do gênero Amblyomma como caracterísiticas morfológicas adicionais para a identificação dos estágios imaturos.

Variabilidade intraespecífica e interespecífica das estruturas tegumentares sobre o idiossoma.bitstream/CPAF-RO-2009-09/12171/1/bpd45_porotaxia-em-larvas-de-carrapatos.pd

Potential drivers of virulence evolution in aquaculture

Infectious diseases are economically detrimental to aquaculture, and with continued expansion and intensification of aquaculture, the importance of managing infectious diseases will likely increase in the future. Here, we use evolution of virulence theory, along with examples, to identify aquaculture practices that might lead to the evolution of increased pathogen virulence. We identify eight practices common in aquaculture that theory predicts may favor evolution toward higher pathogen virulence. Four are related to intensive aquaculture operations, and four others are related specifically to infectious disease control. Our intention is to make aquaculture managers aware of these risks, such that with increased vigilance, they might be able to detect and prevent the emergence and spread of increasingly troublesome pathogen strains in the future

Metodologia para o estudo da porotaxia em larvas de carrapatos Ixodidae.

A determinação específica do estágio larval dos ixodídeos tem sido um imenso problema para a sistemática nos últimos anos. Este trabalho visa a elaboração de uma metodologia de descrição de nomenclatura para as larvas de Ixodidae.bitstream/item/24724/1/cot321-carrapato.pd