1,284 research outputs found
Partial separability and entanglement criteria for multiqubit quantum states
We explore the subtle relationships between partial separability and
entanglement of subsystems in multiqubit quantum states and give experimentally
accessible conditions that distinguish between various classes and levels of
partial separability in a hierarchical order. These conditions take the form of
bounds on the correlations of locally orthogonal observables. Violations of
such inequalities give strong sufficient criteria for various forms of partial
inseparability and multiqubit entanglement. The strength of these criteria is
illustrated by showing that they are stronger than several other well-known
entanglement criteria (the fidelity criterion, violation of Mermin-type
separability inequalities, the Laskowski-\.Zukowski criterion and the
D\"ur-Cirac criterion), and also by showing their great noise robustness for a
variety of multiqubit states, including N-qubit GHZ states and Dicke states.
Furthermore, for N greater than or equal to 3 they can detect bound entangled
states. For all these states, the required number of measurement settings for
implementation of the entanglement criteria is shown to be only N+1. If one
chooses the familiar Pauli matrices as single-qubit observables, the
inequalities take the form of bounds on the anti-diagonal matrix elements of a
state in terms of its diagonal matrix elements.Comment: 25 pages, 3 figures. v4: published versio
Diffractive energy spreading and its semiclassical limit
We consider driven systems where the driving induces jumps in energy space:
(1) particles pulsed by a step potential; (2) particles in a box with a moving
wall; (3) particles in a ring driven by an electro-motive-force. In all these
cases the route towards quantum-classical correspondence is highly non-trivial.
Some insight is gained by observing that the dynamics in energy space, where
is the level index, is essentially the same as that of Bloch electrons in a
tight binding model, where is the site index. The mean level spacing is
like a constant electric field and the driving induces long range hopping
1/(n-m).Comment: 19 pages, 11 figs, published version with some improved figure
Trapped surfaces, horizons and exact solutions in higher dimensions
A very simple criterion to ascertain if (D-2)-surfaces are trapped in
arbitrary D-dimensional Lorentzian manifolds is given. The result is purely
geometric, independent of the particular gravitational theory, of any field
equations or of any other conditions. Many physical applications arise, a few
shown here: a definition of general horizon, which reduces to the standard one
in black holes/rings and other known cases; the classification of solutions
with a (D-2)-dimensional abelian group of motions and the invariance of the
trapping under simple dimensional reductions of the
Kaluza-Klein/string/M-theory type. Finally, a stronger result involving closed
trapped surfaces is presented. It provides in particular a simple sufficient
condition for their absence.Comment: 7 pages, no figures, final version to appear in Class. Quantum Gra
Quadratic Bell inequalities as tests for multipartite entanglement
This letter presents quantum mechanical inequalities which distinguish, for
systems of spin-\half particles (), between fully entangled states
and states in which at most particles are entangled. These inequalities
are stronger than those obtained by Gisin and Bechmann-Pasquinucci [Phys.\
Lett. A {\bf 246}, 1 (1998)] and by Seevinck and Svetlichny [quant-ph/0201046].Comment: 4 pages, including 1 figure. Typo's removed and one proof simplified
in revised versio
Mod4J: A Qualitative Case Study of Model-Driven Software Development
Model-driven software development (MDSD) has been on the rise over the past few years and is becoming more and more mature. However, evaluation in real-life industrial context is still scarce. In this paper, we present a case-study evaluating the applicability of a state-of-the-art MDSD tool, Mod4J, a suite of domain specific languages (DSLs) for developing administrative enterprise applications. Mod4J was used to partially rebuild an industrially representative application. This implementation was then compared to a base implementation based on elicited success criteria. Our evaluation leads to a number of recommendations to improve Mod4J. We conclude that having extension points for hand-written code is a good feature for a model driven software development environment
CT Radiomics in Colorectal Cancer: Detection of KRAS Mutation Using Texture Analysis and Machine Learning
In this work, by using descriptive techniques, the characteristics of the texture of the CT (computed tomography) image of patients with colorectal cancer were extracted and, subsequently, classified in KRAS+ or KRAS-. This was accomplished by using different classifiers, such as Support Vector Machine (SVM), Grading Boosting Machine (GBM), Neural Networks (NNET), and Random Forest (RF). Texture analysis can provide a quantitative assessment of tumour heterogeneity by analysing both the distribution and relationship between the pixels in the image. The objective of this research is to demonstrate that CT-based Radiomics can predict the presence of mutation in the KRAS gene in colorectal cancer. This is a retrospective study, with 47 patients from the University Hospital, with a confirmatory pathological analysis of KRAS mutation. The highest accuracy and kappa achieved were 83% and 64.7%, respectively, with a sensitivity of 88.9% and a specificity of 75.0%, achieved by the NNET classifier using the texture feature vectors combining wavelet transform and Haralick coefficients. The fact of being able to identify the genetic expression of a tumour without having to perform either a biopsy or a genetic test is a great advantage, because it prevents invasive procedures that involve complications and may present biases in the sample. As well, it leads towards a more personalized and effective treatmentThis work has received financial support from the Xunta de Galicia (Centro singular de investigación de Galicia, accreditation 2020–2023) and the European Union (European Regional Development Fund—ERDF), Project MTM2016-76969-PS
Is The Netherlands a spring stopover site for Black-tailed Godwits breeding in European Russia?
Is The Netherlands a spring stopover site for Black-tailed Godwits breeding in European Russia?
Is The Netherlands a spring stopover site for Black-tailed Godwits breeding in European Russia?
Is The Netherlands a spring stopover site for Black-tailed Godwits breeding in European Russia?
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