228 research outputs found
Resonant cancellation of off-resonant effects in a multilevel qubit
Off-resonant effects are a significant source of error in quantum
computation. This paper presents a group theoretic proof that off-resonant
transitions to the higher levels of a multilevel qubit can be completely
prevented in principle. This result can be generalized to prevent unwanted
transitions due to qubit-qubit interactions. A simple scheme exploiting dynamic
pulse control techniques is presented that can cancel transitions to higher
states to arbitrary accuracy.Comment: 4 pages, Revtex, submitted for publicatio
Weak Localization Effect in Superconductors by Radiation Damage
Large reductions of the superconducting transition temperature and
the accompanying loss of the thermal electrical resistivity (electron-phonon
interaction) due to radiation damage have been observed for several A15
compounds, Chevrel phase and Ternary superconductors, and in
the high fluence regime. We examine these behaviors based on the recent theory
of weak localization effect in superconductors. We find a good fitting to the
experimental data. In particular, weak localization correction to the
phonon-mediated interaction is derived from the density correlation function.
It is shown that weak localization has a strong influence on both the
phonon-mediated interaction and the electron-phonon interaction, which leads to
the universal correlation of and resistance ratio.Comment: 16 pages plus 3 figures, revtex, 76 references, For more information,
Plesse see http://www.fen.bilkent.edu.tr/~yjki
Constraints on Dark Matter Annihilation in Clusters of Galaxies with the Fermi Large Area Telescope
Nearby clusters and groups of galaxies are potentially bright sources of
high-energy gamma-ray emission resulting from the pair-annihilation of dark
matter particles. However, no significant gamma-ray emission has been detected
so far from clusters in the first 11 months of observations with the Fermi
Large Area Telescope. We interpret this non-detection in terms of constraints
on dark matter particle properties. In particular for leptonic annihilation
final states and particle masses greater than ~200 GeV, gamma-ray emission from
inverse Compton scattering of CMB photons is expected to dominate the dark
matter annihilation signal from clusters, and our gamma-ray limits exclude
large regions of the parameter space that would give a good fit to the recent
anomalous Pamela and Fermi-LAT electron-positron measurements. We also present
constraints on the annihilation of more standard dark matter candidates, such
as the lightest neutralino of supersymmetric models. The constraints are
particularly strong when including the fact that clusters are known to contain
substructure at least on galaxy scales, increasing the expected gamma-ray flux
by a factor of ~5 over a smooth-halo assumption. We also explore the effect of
uncertainties in cluster dark matter density profiles, finding a systematic
uncertainty in the constraints of roughly a factor of two, but similar overall
conclusions. In this work, we focus on deriving limits on dark matter models; a
more general consideration of the Fermi-LAT data on clusters and clusters as
gamma-ray sources is forthcoming.Comment: accepted to JCAP, Corresponding authors: T.E. Jeltema and S. Profumo,
minor revisions to be consistent with accepted versio
Memorias : Coloquio Vida Cotidiana y Diseño
1 archivo PDF (259 pĂĄginas)Memorias del coloquio realizado en noviembre de 2007 en las instalaciones de la UAM Azcapotzalco en donde la temĂĄtica, incluyĂł investigaciones variadas que iban desde utensilios para comer hasta las librerĂas y vecindades en el siglo XIX, pasando por el diseño japonĂ©s, empaques y embalajes, cooperativas y la España Musulmana, todo esto relacionado con la vida cotidiana ya que dicho concepto estĂĄ modificando la manera en que los cientĂficos sociales se acercan a la realidad
AcĂșmulo de macronutrientes em cana-de-açĂșcar em função da adubação nitrogenada e dos resĂduos culturais incorporados ao solo no plantio
Efeito da queima da palhada da cana-de-açĂșcar e de aplicaçÔes de vinhaça e adubo nitrogenado em caracterĂsticas tecnolĂłgicas da cultura
Produtividade da cana-de-açĂșcar relacionada ao nitrogĂȘnio residual da adubação e do sistema radicular
Efeito residual da adubação na cana-planta e da adubação nitrogenada e potåssica na cana-soca colhidas com e sem a queima da palhada
Stalk yield and technological attributes of planted cane as related to nitrogen fertilization
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