Fidelity for Multimode Thermal Squeezed States

In the theory of quantum transmission of information the concept of fidelity plays a fundamental role. An important class of channels, which can be experimentally realized in quantum optics, is that of Gaussian quantum channels. In this work we present a general formula for fidelity in the case of two arbitrary Gaussian states. From this formula one can get a previous result (H. Scutaru, J. Phys. A: Mat. Gen {\bf 31}, 3659 (1998)), for the case of a single mode; or, one can apply it to obtain a closed compact expression for multimode thermal states.Comment: 5 pages, RevTex, submitted to Phys. Rev.

Transition probabilities between quasifree states

We obtain a general formula for the transition probabilities between any state of the algebra of the canonical commutation relations (CCR-algebra) and a squeezed quasifree state. Applications of this formula are made for the case of multimode thermal squeezed states of quantum optics using a general canonical decomposition of the correlation matrix valid for any quasifree state. In the particular case of a one mode CCR-algebra we show that the transition probability between two quasifree squeezed states is a decreasing function of the geodesic distance between the points of the upper half plane representing these states. In the special case of the purification map it is shown that the transition probability between the state of the enlarged system and the product state of real and fictitious subsystems can be a measure for the entanglement.Comment: 13 pages, REVTeX, no figure

Du droit de protection à la protection des droits des enfants : acteurs et processus réformateur en Roumanie (1995-2004)

In 2004, Romania enacted a law transposing the UN Convention on the Rights of the child in national legislation. However, in the beginning of the 1990s, when the appalling situation of Romania’s institutionalized children was discovered, this improvement seemed unattainable. Therefore, this study addresses the ten years reform process and the role of involved stakeholders, putting an emphasis on individual or institutional internal actors. This paper shows that the National Authority for the Protection of Child Right and Adoption plaid a key role in reforming the Romanian child protection system. Indeed, none of this would have been possible without internal stakeholders (civil society, institutions, etc.) sustaining this issue. But this paper also emphasises that the interdependence between internal and external stakeholders allowed for these vital reforms

Scientometric analysis of the world-wide research efforts concerning Leishmaniasis

<p>Abstract</p> <p>Background</p> <p>Leishmaniasis is a chronic disease that is found in various countries of the world. The aim of the current study was to investigate the impact of leishmaniasis on the world's research output. The present study assessed benchmarking of research output for the period between 1957 and 2006. Using large database analyses, research in the field of leishmaniasis was evaluated. Furthermore, cooperation between different countries was identified.</p> <p>Results</p> <p>The number of publications increased with time. Most publications came from Western countries such as the US, UK or Germany. Interestingly, countries like Brazil and India had a high research output. We found a substantial amount of cooperation between countries.</p> <p>Conclusion</p> <p>Although leishmaniasis is of limited geographic distribution it attracts a wide research interest. The central hub of research cooperation is the USA.</p

Effect of two sous-vide cooking methods on fatty acid composition and oxidative stability of longissimus thoracis muscle from pigs receiving a diet containing or not extruded linseed

To verify the effects of two different sous-vide cooking conditions on lipid oxidation and fatty acid (FA) composition of longissimus thoracis (LT) muscle, 24 pigs, evenly divided into two groups of 12 subjects each, were used. One group received a barley-soya bean meal diet (C) and the second was given the same feed where 5% of extruded linseed partly replaced barley, to obtain a n-3 FA enriched diet (L). At slaughter, from each left half carcase, two samples of LT muscle were collected, packed under vacuum and stored at −18 °C until analysis. The samples were cooked in water bath according to two different methods: at high temperature (80 °C) and short-time i.e. samples left until the core temperaturereached 70 °C (A); at low temperature (60 °C) and long-time (15 h) (B). After cooking, the samples were refrigerated (2 °C) for 24 h. Oxidative stability was measured by a dosage of the 2-thiobarbituric acid reactive substances (TBARS) content, expressed as milligrams of malondialdehyde (MDA)/kg of meat, and FA composition was determined by capillary gas chromatography. The content of each fatty acid is expressed as a percentage of the total FAs detected. The statistical analysis was performed by means of ANOVA, using the GLM procedure of SAS. Dietary treatment (C vs. L) and cooking condition (A vs. B) were used as independent variables. The different sous-vide cooking conditions affected neither lipid oxidation nor FAs percentage of LT muscle. Extruded linseed feeding brought about an increase of the percentage of total n–3 FA (2.67 vs. 0.98; p&lt;.01) and also of polyunsaturated fatty acids (12.02 vs. 9.68; p&lt;.01) in intramuscular fat but did not affect lipid oxidation. This enabled to obtain pork with a more favourable n–6/n–3 ratio (3.68 vs. 10.42 in L and C group, respectively; p&lt;.01), according to the global health guidelines. Thus, an enriched linseed diet ameliorates the FA composition of pork. The effect of the two different sous-vide cooking methods on lipid composition and oxidative stability of pork does not differ, irrespective of dietary treatments

Renyi-Wehrl entropies as measures of localization in phase space

We generalize the concept of the Wehrl entropy of quantum states which gives a basis-independent measure of their localization in phase space. We discuss the minimal values and the typical values of these R{enyi-Wehrl entropies for pure states for spin systems. According to Lieb's conjecture the minimal values are provided by the spin coherent states. Though Lieb's conjecture remains unproven, we give new proofs of partial results that may be generalized for other systems. We also investigate random pure states and calculate the mean Renyi-Wehrl entropies averaged over the natural measure in the space of pure quantum states.Comment: 18 pages, no figures, some improved versions of main proofs, added J.referenc

Geometric observation for the Bures fidelity between two states of a qubit

In this Brief Report, we present a geometric observation for the Bures fidelity between two states of a qubit.Comment: 4 pages, 1 figure, RevTex, Accepted by Phys. Rev.

Quantum optics in the phase space - A tutorial on Gaussian states

In this tutorial, we introduce the basic concepts and mathematical tools needed for phase-space description of a very common class of states, whose phase properties are described by Gaussian Wigner functions: the Gaussian states. In particular, we address their manipulation, evolution and characterization in view of their application to quantum information.Comment: Tutorial. 23 pages, 1 figure. Updated version accepted for publication in EPJ - ST devoted to the memory of Federico Casagrand

Markovian Master Equations: A Critical Study

We derive Markovian master equations of single and interacting harmonic systems in different scenarios, including strong internal coupling. By comparing the dynamics resulting from the corresponding Markovian master equations with exact numerical simulations of the evolution of the global system, we precisely delimit their validity regimes and assess the robustness of the assumptions usually made in the process of deriving the reduced dynamics. The proposed method is sufficiently general to suggest that the conclusions made here are widely applicable to a large class of settings involving interacting chains subject to a weak interaction with an environment.Comment: 40 pages, 14 figures, final versio

Localization of Events in Space-Time

The present paper deals with the quantum coordinates of an event in space-time, individuated by a quantum object. It is known that these observables cannot be described by self-adjoint operators or by the corresponding spectral projection-valued measure. We describe them by means of a positive-operator-valued (POV) measure in the Minkowski space-time, satisfying a suitable covariance condition with respect to the Poincare' group. This POV measure determines the probability that a measurement of the coordinates of the event gives results belonging to a given set in space-time. We show that this measure must vanish on the vacuum and the one-particle states, which cannot define any event. We give a general expression for the Poincare' covariant POV measures. We define the baricentric events, which lie on the world-line of the centre-of-mass, and we find a simple expression for the average values of their coordinates. Finally, we discuss the conditions which permit the determination of the coordinates with an arbitrary accuracy.Comment: 31 pages, latex, no figure