Quantum states with a positive partial transpose are useful for metrology

We show that multipartite quantum states that have a positive partial transpose with respect to all bipartitions of the particles can outperform separable states in linear interferometers. We introduce a powerful iterative method to find such states. We present some examples for multipartite states and examine the scaling of the precision with the particle number. Some bipartite examples are also shown that possess an entanglement very robust to noise. We also discuss the relation of metrological usefulness to Bell inequality violation. We find that quantum states that do not violate any Bell inequality can outperform separable states metrologically. We present such states with a positive partial transpose, as well as with a non-positive positive partial transpose.Comment: 6 pages including two figures + three-page supplement including two figures using revtex 4.1, with numerically obtained density matrices as text files; v2: published version; v3: published version, typo in the 4x4 bound entangled state is corrected (noticed by Peng Yin

Két mikroszkópikus gombafaj együttes károsítása szíriai selyemkórón (Asclepias syriaca L.) a Hajdúsági kistérségben

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HIV-pozitív én-elbeszélések. Metadiegetikus és extradiegetikus narratívák szerepe az identifikációban - (Szub)kultúra létrejötte az elbeszélésben/elbeszéltségben

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Hysteretic behavior of spatially coupled phase-oscillators

Motivated by phenomena related to biological systems such as the synchronously flashing swarms of fireflies, we investigate a network of phase oscillators evolving under the generalized Kuramoto model with inertia. A distance-dependent, spatial coupling between the oscillators is considered. Zeroth and first order kernel functions with finite kernel radii were chosen to investigate the effect of local interactions. The hysteretic dynamics of the synchronization depending on the coupling parameter was analyzed for different kernel radii. Numerical investigations demonstrate that (1) locally locked clusters develop for small coupling strength values, (2) the hysteretic behavior vanishes for small kernel radii, (3) the ratio of the kernel radius and the maximal distance between the oscillators characterizes the behavior of the network

Semiclassical theory of the magnetization process of the triangular lattice Heisenberg model

Motivated by the numerous examples of 1/3 magnetization plateaux in the triangular lattice Heisenberg an- tiferromagnet with spins ranging from 1/2 to 5/2, we revisit the semiclassical calculation of the magnetization curve of that model, with the aim of coming up with a simple method that allows one to calculate the full mag- netization curve, and not just the critical fields of the 1/3 plateau. We show that it is actually possible to calculate the magnetization curve including the first quantum corrections and the appearance of the 1/3 plateau entirely within linear spin-wave theory, with predictions for the critical fields that agree to order 1/S with those derived a long-time ago on the basis of arguments that required to go beyond linear spin-wave theory. This calculation relies on the central observation that there is a kink in the semiclassical energy at the field where the classical ground state is the collinear up-up-down structure, and that this kink gives rise to a locally linear behavior of the energy with the field when all semiclassical ground states are compared to each other for all fields. The magnetization curves calculated in this way for spin 1/2, 1 and 5/2 are shown to be in good agreement with available experimental data.Comment: 11 pages - 7 figure

A személyre szabott betegoktatás lehetőségei

A betegek oktatásának fontos szerepe van a betegségek prevenciójában és terápiájában. Az oktatás lehetővé teszi a szükséges információk átadását, a készségek fejlesztését, valamint a megfelelő motivációk kialakítását, a betegséggel való megküzdés támogatását. Bár számos információforrás rendelkezésre áll, továbbra is szükség van szervezett betegoktatásra. A személyre szabott betegoktatás hatékonyabbnak bizonyult, mint az általános oktatóanyagok használata. Az információtechnológia megfelelő alkalmazása lehetővé teszi a személyre szabott oktatás széles körű, költséghatékony megvalósítását. A szerzők megvizsgálják, hogy egy ilyen rendszer kialakításához milyen komponensekre van szükség. Orv. Hetil., 2013, 154, 403–408. | Patient education has an important role in the prevention and therapy. It enables the delivery of necessary information, development of skills and motivations and supporting to cope with the disease. Although many information sources are available, it is still necessary to provide organized patient education. Tailored patient education was proved to be more effective than using general information materials. The proper use of information technology enables the widespread and cost-effective implementation of tailored patient education. The authors analyse the components necessary for development of such a system. Orv. Hetil., 2013, 154, 403–408