61,739 research outputs found

    On Locality of Schmidt-Correlated States

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    We review some results on the equivalence of quantum states under local unitary transformations (LUT). In particular, the classification of two-qubit Schmidt correlated (SC) states under LUT is investigated. By presenting the standard form of quantum states under LUT, the sufficient and necessary conditions of whether two different SC states are local unitary equivalent are provided. The correlations of SC states are also discussed.Comment: 14 page

    Complete Entanglement Witness for Quantum Teleportation

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    We propose a set of linear quantum entanglement witnesses constituted by local quantum-mechanical observables with each two possible measurement outcomes. These witnesses detect all the entangled resources which give rise to a better fidelity than separable states in quantum teleportation and present both sufficient and necessary conditions in experimentally detecting the useful resources for quantum teleportation.Comment: 3 page

    The fiscal framework and urban infrastructure finance in China

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    China has experienced more than 25 years of extraordinary economic growth. Underlying this growth has been a decentralized fiscal system, in which provinces and large cities are given the freedom to make infrastructure investmentsto stimulate local development, and are allowed to retain a large part of the fiscal revenues that are generated from economic activity. Although successful as a growth strategy, this policy created two problems for national fiscal management. First, it significantly reduced the central government's share of fiscal revenues, which fell from 34.8 percent in 1980 to 22 percent in 1992. Second, it widened economic and fiscal disparities between the rapidly growing urban coastal region and the rest of the country. Rapid growth in subnational debt (which rose 23-fold in a decade) and subnational nonperforming loans (estimated by the authors to range between US100billionandUS100 billion and US150 billion) has placed pressure on China's financial system. Traditionally, China has favored bank lending as a source of finance because the banking system has provided a vehicle for central political control over local debt. But as China's financial system matures, creditworthiness standards must become more important. The authors recommend greater use of the revenue streams from infrastructure assets as a financing source, and gradual relaxation of central political control over subnational debt. One step in this direction would permit leading cities to issue municipal bonds based on objective financial standards.Banks&Banking Reform,Urban Economics,Public&Municipal Finance,Municipal Financial Management,Intergovernmental Fiscal Relations and Local Finance Management

    The Contribution of Social Networks to Income Inequality in Rural China: A Regression-Based Decomposition and Cross-Regional Comparison

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    This study aims to quantify the contribution of social networks, i.e., guanxi,to income inequality in rural households in China. One purpose is to understand how this influence varies across regions with different levels of marketization and economic development. Employing household survey data in rural China, we find that social networks contribute 12.1%-13.4% to income inequality among households in rural China, ranking fourth after village identifiers, nonfarm employment, and education. We also find that social networks exert a greater impact on income and a greater contribution to income inequality in Eastern China, compared with Middle-Western China where economic development is relatively slower. Our findings challenge the conventional understanding that social capital is the capital of the poor. In other words,the rich get richer in richer regions through social networks.Social Network, Income Inequality, Marketization, Regression-Based Decomposition

    Pion Production in Heavy-ion Collisions in the 1 A GeV region

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    Within the framework of the improved isospin dependent quantum molecular dynamics (ImIQMD) model, the pion emission in heavy-ion collisions in the region 1 A GeV is investigated systematically, in which the pion is considered to be mainly produced by the decay of resonances \triangle(1232) and N*(1440). The in-medium dependence and Coulomb effects of the pion production are included in the calculation. Total pion multiplicity and π/π+\pi^{-}/\pi^{+} yields are calculated for the reaction 197^{197}Au+197^{197}Au in central collisions for selected Skyrme parameters SkP, SLy6, Ska, SIII and compared them with the measured data by the FOPI collaboration.Comment: 9 pages, 5 figure

    Necessity for quantum coherence of nondegeneracy in energy flow

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    In this work, we show that the quantum coherence among non-degenerate energy subspaces (CANES) is essential for the energy flow in any quantum system. CANES satisfies almost all of the requirements as a coherence measure, except that the coherence within degenerate subspaces is explicitly eliminated.We show that the energy of a system becomes frozen if and only if the corresponding CANES vanishes, which is true regardless of the form of interaction with the environment. However, CANES can remain zero even if the entanglement changes over time. Furthermore, we show how the power of energy flow is bounded by the value of CANES. An explicit relation connecting the variation of energy and CANES is also presented. These results allow us to bound the generation of system-environment correlation through the local measurement of the system's energy flow
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