Analysis of high quality superconducting resonators: consequences for TLS properties in amorphous oxides

$1/f$ noise caused by microscopic Two-Level Systems (TLS) is known to be very detrimental to the performance of superconducting quantum devices but the nature of these TLS is still poorly understood. Recent experiments with superconducting resonators indicates that interaction between TLS in the oxide at the film-substrate interface is not negligible. Here we present data on the loss and $1/f$ frequency noise from two different Nb resonators with and without Pt capping and discuss what conclusions can be drawn regarding the properties of TLS in amorphous oxides. We also estimate the concentration and dipole moment of the TLS.Comment: 8 pages, 5 figure

Exact solution for the dynamical decoupling of a qubit with telegraph noise

We study the dissipative dynamics of a qubit that is afflicted by classical random telegraph noise and it is subject to dynamical decoupling. We derive exact formulas for the qubit dynamics at arbitrary working points in the limit of infinitely strong control pulses (bang-bang control) and we investigate in great detail the efficiency of the dynamical decoupling techniques both for Gaussian and non-Gaussian (slow) noise at qubit pure dephasing and at optimal point. We demonstrate that control sequences can be successfully implemented as diagnostic tools to infer spectral proprieties of a few fluctuators interacting with the qubit. The analysis is extended in order to include the effect of noise in the pulses and we give upper bounds on the noise levels that can be tolerated in the pulses while still achieving efficient dynamical decoupling performance

Decoherence due to discrete noise in Josephson qubits

We study decoherence produced by a discrete environment on a charge Josephson qubit by introducing a model of an environment of bistable fluctuators. In particular we address the effect of $1/f$ noise where memory effects play an important role. We perform a detailed investigation of various computation procedures (single shot measurements, repeated measurements) and discuss the problem of the information needed to characterize the effect of the environment. Although in general information beyond the power spectrum is needed, in many situations this results in the knowledge of only one more microscopic parameter of the environment. This allows to determine which degrees of freedom of the environment are effective sources of decoherence in each different physical situation considered.Comment: 20 pages, 11 figure

Structured environments in solid state systems: crossover from Gaussian to non-Gaussian behavior

The variety of noise sources typical of the solid state represents the main limitation toward the realization of controllable and reliable quantum nanocircuits, as those allowing quantum computation. Such ``structured environments'' are characterized by a non-monotonous noise spectrum sometimes showing resonances at selected frequencies. Here we focus on a prototype structured environment model: a two-state impurity linearly coupled to a dissipative harmonic bath. We identify the time scale separating Gaussian and non-Gaussian dynamical regimes of the Spin-Boson impurity. By using a path-integral approach we show that a qubit interacting with such a structured bath may probe the variety of environmental dynamical regimes.Comment: 8 pages, 9 figures. Proceedings of the DECONS '06 Conferenc

Projeção de demanda em empresas de serviços: um estudo em um estabelecimento de emissão de certificados digitais

Previsões de demanda são importantes na gestão dos recursos das empresas, porém pouco exploradas em empresas prestadoras de serviços, devido às peculiaridades desse segmento. O presente artigo tem como objetivo utilizar técnicas de previsão de demanda como ferramenta auxiliar na gestão de empresas prestadoras de serviços de tecnologia da informação. Para isso, foi feito um estudo de caso em uma empresa de emissão de certificados digitais. Nessa empresa, ocorreu a análise quantitativa de previsão de demanda a fim de auxiliar na melhoria da produtividade e qualidade de serviço prestado. Os resultados indicam que as técnicas de projeção de demanda contribuem na gestão de empresas prestadoras de serviços. Em especial, no estudo de caso realizado, contribui para a gestão de estoque e diminuição do tempo de atendimento dos clientes

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

BRIDGE: An Open-Label Phase II Trial Evaluating the Safety of Bevacizumab + Carboplatin/Paclitaxel as First-Line Treatment for Patients with Advanced, Previously Untreated, Squamous Non-small Cell Lung Cancer

Background:Patients with predominantly squamous non-small cell lung cancer (NSCLC) have been generally excluded from studies of bevacizumab treatment, because squamous histology was identified as a possible risk factor for severe (grade ≥3) pulmonary hemorrhage (PH) in a phase II study. BRIDGE was designed to determine whether delaying initiation of bevacizumab treatment and selecting patients without baseline risk factors for PH would lower the incidence of severe PH among patients with squamous NSCLC.Methods:Patients in this open-label, single-arm study were treated with carboplatin/paclitaxel for two cycles, followed by carboplatin/paclitaxel and bevacizumab in cycles 3 to 6, followed by bevacizumab until progression or unacceptable toxicity. Eligible patients had stage IIIb, stage IV, or recurrent squamous NSCLC. The primary end point was incidence of grade ≥3 PH.Results:Grade ≥3 PH occurred in 1 of 31 patients who received ≥1 dose of bevacizumab: estimated incidence was 3.2% (90% confidence interval 0.3–13.5%). The patient experienced grade 3 PH, discontinued from the study, then experienced grade 4 PH 10 days later, and died of progressive disease. No other serious bleeding events occurred. Nine patients (29.0%) experienced grade 3 adverse events, including five with hypertension; five patients experienced grade 4 adverse events (dyspnea, PH, basal ganglia infarction, cerebral ischemia, and pain). Median progression-free survival was 6.2 months (95% confidence interval 5.32–7.62 months).Conclusions:The incidence of grade ≥3 PH was 3.2% (one patient). No new safety signals were identified. Although the rate of PH was low, the number of patients in this study was also low. Treatment of squamous NSCLC with bevacizumab should be considered experimental

Green Technology: Bacteria-Based Approach Could Lead to Unsuspected Microbe–Plant–Animal Interactions

The recent and massive revival of green strategies to control plant diseases, mainly as a consequence of the Integrated Pest Management (IPM) rules issued in 2009 by the European Community and the increased consumer awareness of organic products, poses new challenges for human health and food security that need to be addressed in the near future. One of the most important green technologies is biocontrol. This approach is based on living organisms and how these biocontrol agents (BCAs) directly or indirectly interact as a community to control plant pathogens and pest. Although most BCAs have been isolated from plant microbiomes, they share some genomic features, virulence factors, and trans-kingdom infection abilities with human pathogenic microorganisms, thus, their potential impact on human health should be addressed. This evidence, in combination with the outbreaks of human infections associated with consumption of raw fruits and vegetables, opens new questions regarding the role of plants in the human pathogen infection cycle. Moreover, whether BCAs could alter the endophytic bacterial community, thereby leading to the development of new potential human pathogens, is still unclear. In this review, all these issues are debated, highlighting that the research on BCAs and their formulation should include these possible long-lasting consequences of their massive spread in the environment

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

Two-level systems in superconducting quantum devices due to trapped quasiparticles

A major issue for the implementation of large scale superconducting quantum circuits is the interaction with interfacial two-level system defects (TLS) that leads to qubit relaxation and impedes qubit operation in certain frequency ranges that also drift in time. Another major challenge comes from non-equilibrium quasiparticles (QPs) that result in qubit dephasing and relaxation. In this work we show that such QPs can also serve as a source of TLS. Using spectral and temporal mapping of TLS-induced fluctuations in frequency tunable resonators, we identify a subset of the general TLS population that are highly coherent TLS with a low reconfiguration temperature $\sim$ 300 mK, and a non-uniform density of states. These properties can be understood if these TLS are formed by QPs trapped in shallow subgap states formed by spatial fluctutations of the superconducting order parameter $\Delta$. Magnetic field measurements of one such TLS reveals a link to superconductivity. Our results imply that trapped QPs can induce qubit relaxation.Comment: 7 pages, 4 figures, plus 18 pages, 13 figures supplementa