Catalytic quantum teleportation

Quantum catalysis is an intricate feature of quantum entanglement. It demonstrates that in certain situations the very presence of entanglement can improve one's abilities of manipulating other entangled states. At the same time, however, it is not clear if using entanglement catalytically can provide additional power for any of the existing quantum protocols. Here we show, for the first time, that catalysis of entanglement can provide a genuine advantage in the task of quantum teleportation. More specifically, we show that extending the standard teleportation protocol by giving Alice and Bob the ability to use entanglement catalytically, allows them to achieve fidelity of teleportation at least as large as the regularisation of the standard teleportation quantifier, the so-called average fidelity of teleportation. Consequently, we show that this regularised quantifier surpasses the standard benchmark for a variety of quantum states, therefore demonstrating that there are quantum states whose ability to teleport can be further improved when assisted with entanglement in a catalytic way. This hints that entanglement catalysis can be a promising new avenue for exploring novel advantages in the quantum domain.Comment: 6 + 2 pages, 2 figures. Comments welcome

Detecting chaos in particle accelerators through the frequency map analysis method

The motion of beams in particle accelerators is dominated by a plethora of non-linear effects which can enhance chaotic motion and limit their performance. The application of advanced non-linear dynamics methods for detecting and correcting these effects and thereby increasing the region of beam stability plays an essential role during the accelerator design phase but also their operation. After describing the nature of non-linear effects and their impact on performance parameters of different particle accelerator categories, the theory of non-linear particle motion is outlined. The recent developments on the methods employed for the analysis of chaotic beam motion are detailed. In particular, the ability of the frequency map analysis method to detect chaotic motion and guide the correction of non-linear effects is demonstrated in particle tracking simulations but also experimental data.Comment: Submitted for publication in Chaos, Focus Issue: Chaos Detection Methods and Predictabilit

Risk of climate-induced damage in historical textiles

Eleven wool and silk historic textiles and two modern artist's canvases were examined to determine their water vapour adsorption, moisture dimensional response and tensile behaviour. All the textiles showed a similar general pattern of moisture response. A rise in ambient relative humidity (RH) from dry conditions produced expansion of a textile until a certain critical RH level after which a contraction occurred to a greater or lesser degree depending on the yarn crimp and the weave geometry. The largest expansion recorded between the dry state and 80% RH was 1.2 and 0.9% for wool and silk textiles, respectively. The largest shrinkage of 0.8% at high RH range was experienced by a modern linen canvas. Two potential damage mechanisms related to the moisture response of the textiles—stress building as a result of shrinkage of the textile restrained in its dimensional response and the fretting fatigue when yarns move with friction one against another—were found insignificant in typical textile display environments unless the textiles are severely degraded or excessively strained in their mounting

Optical depths for gamma-rays in the radiation field of a star heated by external X-ray source in LMXBs: Application to Her X-1 and Sco X-1

The surface of a low mass star inside a compact low mass X-ray binary system (LMXB) can be heated by the external X-ray source which may appear due to the accretion process onto a companion compact object (a neutron star or a black hole). As a result, the surface temperature of the star can become significantly higher than it is in the normal state resulting from thermonuclear burning. We wonder whether high energy electrons and gamma-rays, injected within the binary system, can efficiently interact with this enhanced radiation field. To decide this, we calculate the optical depths for the gamma-ray photons in the radiation field of such irradiated star as a function of the phase of the binary system. Based on these calculations, we conclude that compact low mass X-ray binary systems may also become sources of high energy gamma-rays since conditions for interaction of electrons and gamma-rays are quite similar to these ones observed within the high mass TeV gamma-ray binaries such as LS 5039 and LSI 303 +61. However, due to differences in the soft radiation field, the expected gamma-ray light curves can significantly differ between low mass and high mass X-ray binaries. As an example, we apply such calculations to two well known LMXBs: Her X-1 and Sco X-1. It is concluded that electrons accelerated to high energies inside these binaries should find enough soft photon target from the companion star for efficient gamma-ray production.Comment: 10 pages, 8 figures, accepted to A&

Multiobject operational tasks for convex quantum resource theories of state-measurement pairs

The prevalent modus operandi within the framework of quantum resource theories has been to characterise and harness the resources within single objects, in what we can call \emph{single-object} quantum resource theories. One can wonder however, whether the resources contained within multiple different types of objects, now in a \emph{multi-object} quantum resource theory, can simultaneously be exploited for the benefit of an operational task. In this work, we introduce examples of such multi-object operational tasks in the form of subchannel discrimination and subchannel exclusion games, in which the player harnesses the resources contained within a state-measurement pair. We prove that for any state-measurement pair in which either of them is resourceful, there exist discrimination and exclusion games for which such a pair outperforms any possible free state-measurement pair. These results hold for arbitrary convex resources of states, and arbitrary convex resources of measurements for which classical post-processing is a free operation. Furthermore, we prove that the advantage in these multi-object operational tasks is determined, in a multiplicative manner, by the resource quantifiers of: \emph{generalised robustness of resource} of both state and measurement for discrimination games and \emph{weight of resource} of both state and measurement for exclusion games.Comment: 5+8 page

The operational significance of the quantum resource theory of Buscemi nonlocality

Although entanglement is necessary for observing nonlocality in a Bell experiment, there are entangled states which can never be used to demonstrate nonlocal correlations. In a seminal paper [PRL 108, 200401 (2012)] F. Buscemi extended the standard Bell experiment by allowing Alice and Bob to be asked quantum, instead of classical, questions. This gives rise to a broader notion of nonlocality, one which can be observed for every entangled state. In this work we study a resource theory of this type of nonlocality referred to as Buscemi nonlocality. We propose a geometric quantifier measuring the ability of a given state and local measurements to produce Buscemi nonlocal correlations and establish its operational significance. In particular, we show that any distributed measurement which can demonstrate Buscemi nonlocal correlations provides strictly better performance than any distributed measurement which does not use entanglement in the task of distributed state discrimination. We also show that the maximal amount of Buscemi nonlocality that can be generated using a given state is precisely equal to its entanglement content. Finally, we prove a quantitative relationship between: Buscemi nonlocality, the ability to perform nonclassical teleportation, and entanglement. Using this relationship we propose new discrimination tasks for which nonclassical teleportation and entanglement lead to an advantage over their classical counterparts.Comment: 10+11 pages, 1 figure. Updated presentation and added clarifications regarding the choice of free set. Comments welcome

Gamma-rays from binary system with energetic pulsar and Be star with aspherical wind: PSR B1259-63/SS2883

At least one massive binary system containing an energetic pulsar, PSR B1259-63/SS2883, has been recently detected in the TeV gamma-rays by the HESS telescopes. These gamma-rays are likely produced by particles accelerated in the vicinity of the pulsar and/or at the pulsar wind shock, in comptonization of soft radiation from the massive star. However, the process of gamma-ray production in such systems can be quite complicated due to the anisotropy of the radiation field, complex structure of the pulsar wind termination shock and possible absorption of produced gamma-rays which might initiate leptonic cascades. In this paper we consider in detail all these effects. We calculate the gamma-ray light curves and spectra for different geometries of the binary system PSR B1259-63/SS2883 and compare them with the TeV gamma-ray observations. We conclude that the leptonic IC model, which takes into account the complex structure of the pulsar wind shock due to the aspherical wind of the massive star, can explain the details of the observed gamma-ray light curve.Comment: 12 pages, 11 figures, accepted for publication in MNRA

Storage of quality malting barley in hermetic plastic bags

The main destination of barley grown in Argentina is malt production. The main standard quality parameter for the malting industry is to maintain at least 98% germination percentage (GP). A typical operation is to harvest dry barley (around 12%) and store it in hermetic plastic bags, a temporary storage system of modified atmosphere, until end use in the malting industry. The objective of this study was to determine whether the typical Argentinean storage condition of malting barley in hermetic plastic bags produces a deleterious effect in its commercial and industrial quality. Two plastic bags filled each with 180 tonnes of malting barley were used for this experiment, one with 11% moisture content (m.c.) and the other with a range between 11 and 11.5% m.c. The experiment began immediately after harvest on December 27th (early summer) and lasted for five months. Carbon dioxide (CO2) concentration, grain temperature, m.c., protein and GP were evaluated every 2 wk. GP did not substantially decrease during the entire storage period for both bags, but samples with higher m.c. had the lowest GP. The protein percentage remained stable throughout the entire evaluation period for both bags. The maximum value of CO2 in the bag with 11% m.c. was 4.4%. The bag with the higher range of m.c. had a maximum CO2 value of 13%, and this high concentration was associated to a small portion of spoiled grain, presumably due to rain water entering the bag through perforations in the plastic cover at the bottom of the bag. It was concluded that it is safe to store quality malting barley with 12% m.c. or less in hermetic plastic bags for five months. Keywords: Silobag, Grain, CO2, Germinatio