Physical Optimization of Quantum Error Correction Circuits

Quantum error correcting codes have been developed to protect a quantum computer from decoherence due to a noisy environment. In this paper, we present two methods for optimizing the physical implementation of such error correction schemes. First, we discuss an optimal quantum circuit implementation of the smallest error-correcting code (the three bit code). Quantum circuits are physically implemented by serial pulses, i.e. by switching on and off external parameters in the Hamiltonian one after another. In contrast to this, we introduce a new parallel switching method that allows faster gate operation by switching all external parameters simultaneously. These two methods are applied to electron spins in coupled quantum dots subject to a Heisenberg coupling H=J(t) S_1*S_2 which can generate the universal quantum gate `square-root-of-swap'. Using parallel pulses, the encoding for three-bit quantum error correction in a Heisenberg system can be accelerated by a factor of about two. We point out that parallel switching has potential applications for arbitrary quantum computer architectures.Comment: 13 pages, 6 figure

Quantitative Treatment of Decoherence

We outline different approaches to define and quantify decoherence. We argue that a measure based on a properly defined norm of deviation of the density matrix is appropriate for quantifying decoherence in quantum registers. For a semiconductor double quantum dot qubit, evaluation of this measure is reviewed. For a general class of decoherence processes, including those occurring in semiconductor qubits, we argue that this measure is additive: It scales linearly with the number of qubits.Comment: Revised version, 26 pages, in LaTeX, 3 EPS figure

hartwegii

Iris hartwegii BakerHartweg's iris, Rainbow iris30 mi. E of Georgetown; Sierra Nevada foothillsYellow pine forest.3000 feetYellow pinePerennial herb; 3.5-4 dm. high; fls yellow-crea

Relative quantification of plasma N-glycans in type II congenital disorder of glycosylation patients by mass spectrometry

Contains fulltext : 203046.pdf (publisher's version ) (Closed access

Forma física, suplementação enzimática e nível nutricional de rações para frangos de corte na fase inicial: desempenho e digestibilidade dos nutrientes Physical form, enzymatic supplementation and nutritional levels of diet for broilers chickens in the initial phase: performance and nutrients digestibility

Foram conduzidos dois experimentos, utilizando um total de 1.440 frangos de corte machos de 8 a 21 dias de idade, para avaliar a forma física da ração, o uso de enzimas e os níveis nutricionais em dietas à base de milho e farelo de soja. Foi adotado delineamento inteiramente casualizado, em esquema fatorial 2 × 2 × 2, com duas formas físicas de ração (farelada ou triturada); sem ou com complexo enzimático (amilase, celulase e protease) e dois níveis nutricionais (95 ou 100% das recomendações). No experimento 1, 1.200 aves foram distribuídas nos oito tratamentos, com cinco repetições de 30 aves cada, para avaliação de consumo de ração, do ganho de peso e da conversão alimentar. Simultaneamente, realizou-se o experimento 2 (ensaio de metabolismo), no qual 240 aves receberam os tratamentos experimentais, com seis repetições de cinco aves cada. Aos 18 dias de idade, iniciou-se a coleta total de excretas, realizada uma vez ao dia, por três dias consecutivos, para determinação da energia metabolizável (EMAn) e dos coeficientes de metabolizabilidade de matéria seca (CMMS), proteína bruta (CMPB) e extrato etéreo das rações experimentais. A forma física da ração e o nível nutricional influenciaram o consumo de ração das aves, mas não o ganho de peso. Houve interação nível nutricional × forma física da ração para EMAn e metabolizabilidade da matéria seca e proteína bruta. A forma física melhora a energia e o CMMS enquanto as enzimas influenciam a metabolizabilidade da matéria seca e proteína bruta. Com exceção do CMPB, as demais características são influenciadas pelo nível nutricional da dieta.<br>A total of 1440 male broiler chickens from 8 to 21 days old was assigned to two experiments to evaluate the physical form of diet, use of enzymes and nutritional levels of corn-soybean meal based diets. A completely randomized design as a 2 × 2 × 2 factorial scheme, two physical forms of diet (meal or crushed), with or without enzimatic complex (amylase, cellulase and protease) and two nutritional levels (95 or 100% of the recommendations), was used. In the experiment 1, 1200 birds were assigned to the eight treatments with five replicates of 30 chickens each, to evaluate the feed intake (FI), weight gain (WG) and feed conversion (FC). The experiment 2 was carried out simultaneously with the metabolism assay, when 240 birds were allotted to eight experimental treatments with six replicates of five birds each. The total excreta collection started at 18 days of age, once a day for three consecutive days, to determine the metabolizable energy (AMEn) and the metabolizability coefficients of dry matter (MCDM), crude protein (MCCP) and ether extract of the experimental diets. The dietary physical form and nutritional level affected feed intake, but not weight gain. Dietary nutritional level × physical form interaction on AMEn and metabolizability of the dry matter and crude protein was also observed. The physical form improves energy and MCDM while the enzymes influence the metabolizability of dry matter and crude protein. Except for MCCP, the other characteristics are influenced by the dietary nutritional level

Efeito do processamento, suplementação enzimática e nível nutricional da ração para frangos de corte no período de 22 a 42 dias de idade Effect of processing, enzymatic supplementation and nutritional levels of the diet for broilers in the period from the 22nd to the 42nd day of age

Objetivando-se avaliar a forma física da ração, o uso de enzimas e níveis nutricionais em dietas à base de milho e farelo de soja, foram conduzidos dois experimentos utilizando um total de 1.344 frangos de corte machos de 22 a 42 dias de idade, distribuídos em um delineamento inteiramente casualizado em esquema fatorial 2 x 2 x 2, sendo duas formas físicas de ração (farelada ou triturada); com ou sem complexo enzimático (amilase, celulase e protease) e dois níveis nutricionais, 95 ou 100% das recomendações de Rostagno et al. (2005). No experimento 1, 1200 aves foram distribuídas nos oito tratamentos com cinco repetições de 30 aves cada para avaliação de consumo de ração (CR), ganho de peso (GP), conversão alimentar (CA) e características de carcaça. Simultaneamente, foi realizado o experimento 2 (ensaio de metabolismo), em que 144 aves foram distribuídas em gaiolas metálicas, recebendo os oito tratamentos experimentais com seis repetições de três aves cada. Aos 38 dias de idade iniciou-se a coleta total de excretas, realizada uma vez ao dia, por três dias consecutivos para determinação da energia metabolizável aparente corrigida (EMAn) e dos coeficientes de metabolizabilidade da matéria seca (CMMS) e proteína bruta (CMPB) das rações experimentais. De uma maneira geral, pelos resultados obtidos, pode-se concluir que a suplementação enzimática não resulta em melhora no desempenho das aves e na digestibilidade dos nutrientes das rações, independentemente da forma física, devendo estas serem formuladas com 100% das recomendações nutricionais.<br>In order to evaluate the physical form of diet and the use of enzymes and nutritional levels in diets based on corn and soybean meal, two experiments were carried out using a total of 1344 male broilers from 22 to 42 days of age, distributed in a randomized design in a 2 x 2 x 2 factorial scheme with two physical forms of diet (meal or crushed), with and without enzymatic complex (amylase, cellulase and protease) and two nutritional levels (95 or 100% of the recommendations). In experiment 1, 1200 birds were distributed to the eight treatments with five replicates of 30 chickens each, to evaluate the feed intake (FI), weight gain (WG) and feed conversion (FC) and carcass traits of birds. Simultaneously, in the experiment 2 (assay metabolism), 144 birds were distributed in metal cages and received the eight experimental treatments in six replicates of three birds each. At 38 days of age the total excreta collection were started, and the collect for three consecutive days to determine the apparent metabolizable energy corrected (AMEn) and the metabolizability coefficients of dry matter (MCDM) and crude protein (MCCP) of experimental diets. In general, the results can conclude that enzyme supplementation results in no improvement in bird performance and nutrient digestibility of diets, regardless of physical form, which should be made with 100% nutritional recommendations