Directed percolation effects emerging from superadditivity of quantum networks

Entanglement indcued non--additivity of classical communication capacity in networks consisting of quantum channels is considered. Communication lattices consisiting of butterfly-type entanglement breaking channels augmented, with some probability, by identity channels are analyzed. The capacity superadditivity in the network is manifested in directed correlated bond percolation which we consider in two flavours: simply directed and randomly oriented. The obtained percolation properties show that high capacity information transfer sets in much faster in the regime of superadditive communication capacity than otherwise possible. As a byproduct, this sheds light on a new type of entanglement based quantum capacity percolation phenomenon.Comment: 6 pages, 4 figure

On photonic controlled phase gates

As primitives for entanglement generation, controlled phase gates take a central role in quantum computing. Especially in ideas realizing instances of quantum computation in linear optical gate arrays a closer look can be rewarding. In such architectures, all effective non-linearities are induced by measurements: Hence the probability of success is a crucial parameter of such quantum gates. In this note, we discuss this question for controlled phase gates that implement an arbitrary phase with one and two control qubits. Within the class of post-selected gates in dual-rail encoding with vacuum ancillas we identify the optimal success probabilities. We construct networks that allow for an implementation by means of todays experimental capabilities in detail. The methods employed here appear specifically useful with the advent of integrated linear optical circuits, providing stable interferometers on monolithic structures.Comment: 9 pages, 6 figures, final versio

Preparation of Knill-Laflamme-Milburn states using tunable controlled phase gate

A specific class of partially entangled states known as Knill-Laflamme-Milburn states (or KLM states) has been proved to be useful in relation to quantum information processing [Knill et al., Nature 409, 46 (2001)]. Although the usage of such states is widely investigated, considerably less effort has been invested into experimentally accessible preparation schemes. This paper discusses the possibility to employ a tunable controlled phase gate to generate an arbitrary Knill-Laflamme-Milburn state. In the first part, the idea of using the controlled phase gate is explained on the case of two-qubit KLM states. Optimization of the proposed scheme is then discussed for the framework of linear optics. Subsequent generalization of the scheme to arbitrary n-qubit KLM state is derived in the second part of this paper.Comment: 5 pages, 4 figures, accepted in Journal of Physics

Brokered Graph State Quantum Computing

We describe a procedure for graph state quantum computing that is tailored to fully exploit the physics of optically active multi-level systems. Leveraging ideas from the literature on distributed computation together with the recent work on probabilistic cluster state synthesis, our model assigns to each physical system two logical qubits: the broker and the client. Groups of brokers negotiate new graph state fragments via a probabilistic optical protocol. Completed fragments are mapped from broker to clients via a simple state transition and measurement. The clients, whose role is to store the nascent graph state long term, remain entirely insulated from failures during the brokerage. We describe an implementation in terms of NV-centres in diamond, where brokers and clients are very naturally embodied as electron and nuclear spins.Comment: 5 pages, 3 figure

Cluster state preparation using gates operating at arbitrary success probabilities

Several physical architectures allow for measurement-based quantum computing using sequential preparation of cluster states by means of probabilistic quantum gates. In such an approach, the order in which partial resources are combined to form the final cluster state turns out to be crucially important. We determine the influence of this classical decision process on the expected size of the final cluster. Extending earlier work, we consider different quantum gates operating at various probabilites of success. For finite resources, we employ a computer algebra system to obtain the provably optimal classical control strategy and derive symbolic results for the expected final size of the cluster. We identify two regimes: When the success probability of the elementary gates is high, the influence of the classical control strategy is found to be negligible. In that case, other figures of merit become more relevant. In contrast, for small probabilities of success, the choice of an appropriate strategy is crucial.Comment: 7 pages, 9 figures, contribution to special issue of New J. Phys. on "Measurement-Based Quantum Information Processing". Replaced with published versio

Schedule for Affective Disorders and Schizophrenia for School-Age Children - Present and Lifetime Version (K-SADS-PL), DSM-5 update: translation into Brazilian Portuguese

Brazilian governmental research funding agency Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Brazilian governmental research funding agency Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Brazilian governmental research funding agency Fundacao de Amparo a Pesquisa do Estado do Rio Grande do Sul (FAPERGS)ShireNovartisEli LillyJanssen-CilagUniv Fed Rio Grande do Sul, Fac Med, Dept Psiquiatria, Porto Alegre, RS, BrazilUniv Fed Rio Grande do Sul, Fac Med, Dept Pediat, Porto Alegre, RS, BrazilUniv Sao Paulo, Fac Med, Dept & Inst Psiquiatria, Sao Paulo, SP, BrazilUniv Fed Sao Paulo, Fac Med, Dept & Inst Psiquiatria, Sao Paulo, SP, BrazilPontifica Univ Catolica Rio Grande do Sul, Dev Cognit Neurosci Res Grp GNCD, Porto Alegre, RS, BrazilInst Bairral Psiquiatria, Ctr Integrado Desenvolvimento Infancia & Adolesce, Itapira, BrazilUniv Fed Sao Paulo, Fac Med, Dept & Inst Psiquiatria, Sao Paulo, SP, BrazilWeb of Scienc

Severity of Ascites Is Associated with Increased Mortality in Patients with Cirrhosis Secondary to Biliary Atresia

Very few prior studies have investigated the presence of ascites as a prognostic factor in children with cirrhosis. To the best of our knowledge, there are no prior studies evaluating the relationship between severity of ascites and patient survival in children with biliary atresia and cirrhosis.Clinically detectable ascites is associated with decreased 1-year survival of children with biliary atresia. These patients should be treated with caution and prioritized for liver transplantation.Background Very few prior studies have investigated the presence of ascites as a prognostic factor in children with cirrhosis. To the best of our knowledge, there are no prior studies evaluating the relationship between severity of ascites and patient survival in children with biliary atresia and cirrhosis. Aims To evaluate the association between severity of ascites and survival of children with cirrhosis and biliary atresia. Methods All children with cirrhosis secondary to biliary atresia evaluated at our institution from 2000 to 2014 were included in this study. Patients were classified into four groups: NA = no ascites; A1 = grade 1 ascites; A2 = grade 2 ascites; and A3 = grade 3 ascites. The primary endpoint of the study was mortality within the first year after patient inclusion. Ninetyday mortality was also evaluated. Prognostic factors related to both endpoints also were studied. [...]info:eu-repo/semantics/publishedVersio

Ground states of unfrustrated spin Hamiltonians satisfy an area law

We show that ground states of unfrustrated quantum spin-1/2 systems on general lattices satisfy an entanglement area law, provided that the Hamiltonian can be decomposed into nearest-neighbor interaction terms which have entangled excited states. The ground state manifold can be efficiently described as the image of a low-dimensional subspace of low Schmidt measure, under an efficiently contractible tree-tensor network. This structure gives rise to the possibility of efficiently simulating the complete ground space (which is in general degenerate). We briefly discuss "non-generic" cases, including highly degenerate interactions with product eigenbases, using a relationship to percolation theory. We finally assess the possibility of using such tree tensor networks to simulate almost frustration-free spin models.Comment: 14 pages, 4 figures, small corrections, added a referenc

Integration of highly probabilistic sources into optical quantum architectures: perpetual quantum computation

In this paper we introduce a design for an optical topological cluster state computer constructed exclusively from a single quantum component. Unlike previous efforts we eliminate the need for on demand, high fidelity photon sources and detectors and replace them with the same device utilised to create photon/photon entanglement. This introduces highly probabilistic elements into the optical architecture while maintaining complete specificity of the structure and operation for a large scale computer. Photons in this system are continually recycled back into the preparation network, allowing for a arbitrarily deep 3D cluster to be prepared using a comparatively small number of photonic qubits and consequently the elimination of high frequency, deterministic photon sources.Comment: 19 pages, 13 Figs (2 Appendices with additional Figs.). Comments welcom