Quantum nonlocality of four-qubit entangled states

Quantum nonlocality of several four-qubit states is investigated by constructing a new Bell inequality. These include the Greenberger-Zeilinger-Horne (GHZ) state, W state, cluster state, and the state $|\chi>$ that has been recently proposed in [PRL, {\bf 96}, 060502 (2006)]. The Bell inequality is optimally violated by $|\chi>$ but not violated by the GHZ state. The cluster state also violates the Bell inequality though not optimally. The state $|\chi>$ can thus be discriminated from the cluster state by using the inequality. Different aspects of four-partite entanglement are also studied by considering the usefulness of a family of four-qubit mixed states as resources for two-qubit teleportation. Our results generalize those in [PRL, {\bf 72}, 797 (1994)].Comment: 13 pages, 1 figur

The nature of solar brightness variations

The solar brightness varies on timescales from minutes to decades. Determining the sources of such variations, often referred to as solar noise, is of importance for multiple reasons: a) it is the background that limits the detection of solar oscillations, b) variability in solar brightness is one of the drivers of the Earth's climate system, c) it is a prototype of stellar variability which is an important limiting factor for the detection of extra-solar planets. Here we show that recent progress in simulations and observations of the Sun makes it finally possible to pinpoint the source of the solar noise. We utilise high-cadence observations from the Solar Dynamic Observatory and the SATIRE model to calculate the magnetically-driven variations of solar brightness. The brightness variations caused by the constantly evolving cellular granulation pattern on the solar surface are computed with the MURAM code. We find that surface magnetic field and granulation can together precisely explain solar noise on timescales from minutes to decades, i.e. ranging over more than six orders of magnitude in the period. This accounts for all timescales that have so far been resolved or covered by irradiance measurements. We demonstrate that no other sources of variability are required to explain the data. Recent measurements of Sun-like stars by CoRoT and Kepler uncovered brightness variations similar to that of the Sun but with much wider variety of patterns. Our finding that solar brightness variations can be replicated in detail with just two well-known sources will greatly simplify future modelling of existing CoRoT and Kepler as well as anticipated TESS and PLATO data.Comment: This is the submitted version of the paper published in Nature Astronom

Unsupervised Fiber Bundles Registration using Weighted Measures Geometric Demons

International audienceBrain image registration aims at reducing anatomical variability across subjects to create a common space for group analysis. Multi-modal approaches intend to minimize cortex shape variations along with internal structures, such as fiber bundles. A di ficulty is that it requires a prior identi fication of these structures, which remains a challenging task in the absence of a complete reference atlas. We propose an extension of the log-Geometric Demons for jointly registering images and fi ber bundles without the need of point or ber correspondences. By representing fi ber bundles as Weighted Measures we can register subjects with di fferent numbers of fiber bundles. The ef ficacy of our algorithm is demonstrated by registering simultaneously T1 images and between 37 and 88 ber bundles depending on each of the ten subject used. We compare results with a multi-modal T1 + Fractional Anisotropy (FA) and a tensor-based registration algorithms and obtain superior performance with our approach

The implication of fertility rate and life expectancy growth towards ASEAN economic growth

This paper investigates the implication of demographic change towards economic growth in ASEAN from 1990 to 2018 by using the panel data from the World Bank Indicators (2019). Since 2010, ASEAN had experienced a continuous decline in GDP per capita growth. A number of literature review report demographic change was the factor that influence GDP per capita growth. Both Panel Least Squares (PLS) and Random Effect (RE) estimation reported that increasing in the labour participation and productivity had a positively influence on economic growth due to economic of scale and competitiveness improvement. Moreover, both fertility rate and life expectancy growth had negatively influence on economic growth where increase in fertility rate and life expectancy raise the child and aged dependency. However, the empirical result show that share of working-age population had no implication towards the economic growth due to the government intervention on interest rate and social security expenditure. Changing in fertility rate and life expectancy provide an important economic opportunity for ASEAN countries expectedly in child dependency reduction and increasing in household saving for both human and physical capital investment. However, the effective policies that may affect labour participation and productivity additional family planning programs should be considered

B meson wave function from the B→γlνB\to\gamma l\nu decay

We show that the leading-power $B$ meson wave function can be extracted reliably from the photon energy spectrum of the $B\to\gamma l\nu$ decay up to $O(1/m_b^2)$ and $O(\alpha_s^2)$ uncertainty, $m_b$ being the $b$ quark mass and $\alpha_s$ the strong coupling constant. The $O(1/m_b)$ corrections from heavy-quark expansion can be absorbed into a redefined leading-power $B$ meson wave function. The two-parton $O(1/m_b)$ corrections cancel exactly, and the three-parton $B$ meson wave functions turn out to contribute at $O(1/m_b^2)$. The constructive long-distance contribution through the $B\to V\to\gamma$ transition, $V$ being a vector meson, almost cancels the destructive $O(\alpha_s)$ radiative correction. Using models of the leading-power $B$ meson wave function available in the literature, we obtain the photon energy spectrum in the perturbative QCD framework, which is then compared with those from other approaches.Comment: 11 pages, 5 figures with minor correction

Intersite coupling effects in a Kondo lattice

The La dilution of the Kondo lattice CeCoIn_5 is studied. The scaling laws found for the magnetic susceptibility and the specific heat reveal two well-separated energy scales, corresponding to the single impurity Kondo temperature T_K and an intersite spin-liquid temperature T^*. The Ce-dilute alloy has the expected Fermi liquid ground state, while the specific heat and resistivity in the dense Kondo regime exhibit non-Fermi-liquid behavior, which scales with T^*. These observations indicate that the screening of the magnetic moments in the lattice involves antiferromagnetic intersite correlations with a larger energy scale in comparison with the Kondo impurity case.Comment: 4 pages, 4 figure

Joint T1 and Brain Fiber Log-Demons Registration Using Currents to Model Geometry

International audienceWe present an extension of the diffeomorphic Geometric Demons algorithm which combines the iconic registration with geometric constraints. Our algorithm works in the log-domain space, so that one can efficiently compute the deformation field of the geometry. We represent the shape of objects of interest in the space of currents which is sensitive to both location and geometric structure of objects. Currents provides a distance between geometric structures that can be defined without specifying explicit point-to-point correspondences. We demonstrate this framework by registering simultaneously T1 images and 65 fiber bundles consistently extracted in 12 subjects and compare it against non-linear T1, tensor, and multi-modal T1+ Fractional Anisotropy (FA) registration algorithms. Results show the superiority of the Log-domain Geometric Demons over their purely iconic counterparts

The Pathway to Low Outlier Status in Venous Thromboembolism Events: An Analysis of Pancreatic Surgery in ACS NSQIP

Introduction: Our institution’s hepatopancreaticobiliary service (HPBS) is a high-volume pancreatic surgery service, which has demonstrated consistently low rates of symptomatic venous thromboembolism (VTE) compared to similar institutions as reported by NSQIP. We sought to determine if the HPBS’s regimented multimodal VTE prophylaxis pathway plays a role in achieving consistently low VTE rates. Methods: We queried the ACS NSQIP Participant User File and our institution’s data from 2011-2016 for major pancreatic operations. We used Chi-squared analysis to compare the HPBS and national patient populations, and created a matched dataset based on preoperative patient factors. Univariate and multivariate analyses were performed on both the aggregate and matched data to determine independent risk factors for symptomatic VTE formation. Results: Among 36,435 NSQIP patients, 850 (2.3%) received surgery by the HPBS. VTE rates were significantly lower for the HPBS (2.0%) compared to the national cohort (3.5%) (p=0.018); this significance was seen in the matched cohort as well (p=0.040). Upon multivariate analysis, having an operation performed by the HPBS independently conferred lower odds of VTE formation in both the aggregate (OR=0.572, p=0.024) and matched (OR=0.530, p=0.041) cohorts. Discussion: The HPBS had statistically lower rates of symptomatic VTE compared to the national cohort as reported by NSQIP. We identified an independent protective effect of the HPBS on VTE formation, which we believe to be due, at least in part, to adherence to a high risk VTE prophylaxis pathway. This pathway could serve as a model for other institutions hoping to improve their VTE rates

Superconducting order parameter in nonmagnetic borocarbides RNi2B2C (R = Y, Lu) probed by point-contact Andreev reflection spectroscopy

We report on the measurements of the superconducting order parameter in the nonmagnetic borocarbides LuNi2B2C and YNi2B2C. Andreev conductance spectra are obtained from nanoscale metallic junctions on single crystal surfaces prepared along three major crystallographic orientations: [001], [110], and [100]. The gap values extracted by the single-gap Blonder-Tinkham-Klapwijk model follow the theoretical predictions as a function of temperature and magnetic field and exhibit a small anisotropy with no indication of proposed gap nodes along the [100] and [010] directions. These observations are robust and reproducible among all the measurements on two different sets of LuNi2B2C crystals and one set of YNi2B2C crystals. We suggest that the possible gap nodes in the [100] direction may be masked by two effects: different gap anisotropy across multiple Fermi surfaces, as reported in the recent photoemission spectroscopy, and the large tunneling cone. Our results provide a consistent picture of the superconducting gap structure in these materials, addressing the controversy particularly in the reported results of point-contact Andreev reflection spectroscopy