Tripartite Entanglement versus Tripartite Nonlocality in Three-Qubit Greenberger-Horne-Zeilinger-Class States

We analyze the relationship between tripartite entanglement and genuine tripartite nonlocality for three-qubit pure states in the Greenberger-Horne-Zeilinger class. We consider a family of states known as the generalized Greenberger-Horne-Zeilinger states and derive an analytical expression relating the three-tangle, which quantifies tripartite entanglement, to the Svetlichny inequality, which is a Bell-type inequality that is violated only when all three qubits are nonlocally correlated. We show that states with three-tangle less than 1/2 do not violate the Svetlichny inequality. On the other hand, a set of states known as the maximal slice states does violate the Svetlichny inequality, and exactly analogous to the two-qubit case, the amount of violation is directly related to the degree of tripartite entanglement.We discuss further interesting properties of the generalized Greenberger-Horne-Zeilinger and maximal slice states

Resonance enhancement of x-rays and fluorescence yield from marker layers in thin films

Resonance enhancement of x rays in a thin film and fluorescence emission from embedded marker layers within the film have been studied. With embedded marker layers of Ti, Fe, and W at different depths in a thin Si film on a Au-coated Si substrate, it has been shown that the position of a marker layer throughout the depth of the film can be unambiguously determined with a precision better than 0.5 nm. In this example, field-intensity enhancement upto 16 times have been observed. Field enhancement gives rise to enhanced sensitivity. The usefulness of this resonance-enhanced x-ray fluorescence spectrometry in the study of diffusion with marker layers in thin films including polymers and nanocomposites has been elucidated

An ex vivo model using human osteoarthritic cartilage demonstrates the release of bioactive insulin-like growth factor-1 from a collagen-glycosaminoglycan scaffold.

Biomimetic scaffolds hold great promise for therapeutic repair of cartilage, but although most scaffolds are tested with cells in vitro, there are very few ex vivo models (EVMs) where adult cartilage and scaffolds are co-cultured to optimize their interaction prior to in vivo studies. This study describes a simple, non-compressive method that is applicable to mammalian or human cartilage and provides a reasonable throughput of samples. Rings of full-depth articular cartilage slices were derived from human donors undergoing knee replacement for osteoarthritis and a 3 mm core of a collagen/glycosaminoglycan biomimetic scaffold (Tigenix, UK) inserted to create the EVM. Adult osteoarthritis chondrocytes were seeded into the scaffold and cultures maintained for up to 30 days. Ex vivo models were stable throughout experiments, and cells remained viable. Chondrocytes seeded into the EVM attached throughout the scaffold and in contact with the cartilage explants. Cell migration and deposition of extracellular matrix proteins in the scaffold was enhanced by growth factors particularly if the scaffold was preloaded with growth factors. This study demonstrates that the EVM represents a suitable model that has potential for testing a range of therapeutic parameters such as numbers/types of cell, growth factors or therapeutic drugs before progressing to costly pre-clinical trials.The authors would like to kindly acknowledge funding from the EPSRC and Tigenix Ltd (LM), Technology Strategy Board and Tigenix Ltd (JW) and the NIHR (DH).This is the final version of the article. It first appeared from Wiley via http://dx.doi.org/10.1002/cbf.3112

Refractories for reheating and heat treatment furnaces

The group of furnaces used for reheating and heat-treatment covers a wide field in the processing of both ferrous and non-ferrous metals. A "re-heating" furnace is utilised to raise the temperature of the metal to prepare it for hot working (shaping), while the "heat-treatment" furnaces are used for stress relieving and for changing the physical properties of the metal after the product has attained its final shape

Endogenous Quasicycles and Stochastic Coherence in a Closed Endemic Model

We study the role of demographic fluctuations in typical endemics as exemplified by the stochastic SIRS model. The birth-death master equation of the model is simulated using exact numerics and analysed within the linear noise approximation. The endemic fixed point is unstable to internal demographic noise, and leads to sustained oscillations. This is ensured when the eigenvalues ($\lambda$) of the linearised drift matrix are complex, which in turn, is possible only if detailed balance is violated. In the oscillatory state, the phases decorrelate asymptotically, distinguishing such oscillations from those produced by external periodic forcing. These so-called quasicycles are of sufficient strength to be detected reliably only when the ratio $|Im(\lambda)/Re(\lambda)|$ is of order unity. The coherence or regularity of these oscillations show a maximum as a function of population size, an effect known variously as stochastic coherence or coherence resonance. We find that stochastic coherence can be simply understood as resulting from a non-monotonic variation of $|Im(\lambda)/Re(\lambda)|$ with population size. Thus, within the linear noise approximation, stochastic coherence can be predicted from a purely deterministic analysis. The non-normality of the linearised drift matrix, associated with the violation of detailed balance, leads to enhanced fluctuations in the population amplitudes.Comment: 21 pages, 8 figure

The GRA Beam-Splitter Experiments and Particle-Wave Duality of Light

Grangier, Roger and Aspect (GRA) performed a beam-splitter experiment to demonstrate the particle behaviour of light and a Mach-Zehnder interferometer experiment to demonstrate the wave behaviour of light. The distinguishing feature of these experiments is the use of a gating system to produce near ideal single photon states. With the demonstration of both wave and particle behaviour (in two mutually exclusive experiments) they claim to have demonstrated the dual particle-wave behaviour of light and hence to have confirmed Bohr's principle of complementarity. The demonstration of the wave behaviour of light is not in dispute. But we want to demonstrate, contrary to the claims of GRA, that their beam-splitter experiment does not conclusively confirm the particle behaviour of light, and hence does not confirm particle-wave duality, nor, more generally, does it confirm complementarity. Our demonstration consists of providing a detailed model based on the Causal Interpretation of Quantum Fields (CIEM), which does not involve the particle concept, of GRA's which-path experiment. We will also give a brief outline of a CIEM model for the second, interference, GRA experiment.Comment: 24 pages, 4 figure

Quantum Stephani exact cosmological solutions and the selection of time variable

We study perfect fluid Stephani quantum cosmological model. In the present work the Schutz's variational formalism which recovers the notion of time is applied. This gives rise to Wheeler-DeWitt equation for the scale factor. We use the eigenfunctions in order to construct wave packets for each case. We study the time-dependent behavior of the expectation value of the scale factor, using many-worlds and deBroglie-Bohm interpretations of quantum mechanics.Comment: 19 pages, 7 figure

GNSS Spoofing Detection via Opportunistic IRIDIUM Signals

In this paper, we study the privately-own IRIDIUM satellite constellation, to provide a location service that is independent of the GNSS. In particular, we apply our findings to propose a new GNSS spoofing detection solution, exploiting unencrypted IRIDIUM Ring Alert (IRA) messages that are broadcast by IRIDIUM satellites. We firstly reverse-engineer many parameters of the IRIDIUM satellite constellation, such as the satellites speed, packet interarrival times, maximum satellite coverage, satellite pass duration, and the satellite beam constellation, to name a few. Later, we adopt the aforementioned statistics to create a detailed model of the satellite network. Subsequently, we propose a solution to detect unintended deviations of a target user from his path, due to GNSS spoofing attacks. We show that our solution can be used efficiently and effectively to verify the position estimated from standard GNSS satellite constellation, and we provide constraints and parameters to fit several application scenarios. All the results reported in this paper, while showing the quality and viability of our proposal, are supported by real data. In particular, we have collected and analyzed hundreds of thousands of IRA messages, thanks to a measurement campaign lasting several days. All the collected data ($1000+$ hours) have been made available to the research community. Our solution is particularly suitable for unattended scenarios such as deserts, rural areas, or open seas, where standard spoofing detection techniques resorting to crowd-sourcing cannot be used due to deployment limitations. Moreover, contrary to competing solutions, our approach does not resort to physical-layer information, dedicated hardware, or multiple receiving stations, while exploiting only a single receiving antenna and publicly-available IRIDIUM transmissions. Finally, novel research directions are also highlighted.Comment: Accepted for the 13th Conference on Security and Privacy in Wireless and Mobile Networks (WISEC), 202

Review of recent experimental progresses in Foundations of Quantum Mechanics and Quantum Information obtained in Parametric Down Conversion Experiments at IENGF

We review some recent experimental progresses concerning Foundations of Quantum Mechanics and Quantum Information obtained in Quantum Optics Laboratory "Carlo Novero" at IENGF. More in details, after a short presentation of our polarization entangled photons source (based on precise superposition of two Type I PDC emission) and of the results obtained with it, we describe an innovative double slit experiment where two degenerate photons produced by PDC are sent each to a specific slit. Beyond representing an interesting example of relation between visibility of interference and "welcher weg" knowledge, this configuration has been suggested for testing de Broglie-Bohm theory against Standard Quantum Mechanics. Our results perfectly fit SQM results, but disagree with dBB predictions. Then, we discuss a recent experiment addressed to clarify the issue of which wave-particle observables are really to be considered when discussing wave particle duality. This experiments realises the Agarwal et al. theoretical proposal, overcoming limitations of a former experiment. Finally, we hint to the realization of a high-intensity high-spectral-selected PDC source to be used for quantum information studies