1,599 research outputs found

    Group theoretical study of LOCC-detection of maximally entangled state using hypothesis testing

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    In the asymptotic setting, the optimal test for hypotheses testing of the maximally entangled state is derived under several locality conditions for measurements. The optimal test is obtained in several cases with the asymptotic framework as well as the finite-sample framework. In addition, the experimental scheme for the optimal test is presented

    Macroscopic thermodynamic reversibility in quantum many-body systems

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    The resource theory of thermal operations, an established model for small-scale thermodynamics, provides an extension of equilibrium thermodynamics to nonequilibrium situations. On a lattice of any dimension with any translation-invariant local Hamiltonian, we identify a large set of translation-invariant states that can be reversibly converted to and from the thermal state with thermal operations and a small amount of coherence. These are the spatially ergodic states, i.e., states that have sharp statistics for any translation-invariant observable, and mixtures of such states with the same thermodynamic potential. As an intermediate result, we show for a general state that if the gap between the min- and the max-relative entropies to the thermal state is small, then the state can be approximately reversibly converted to and from the thermal state with thermal operations and a small source of coherence. Our proof provides a quantum version of the Shannon-McMillan-Breiman theorem for the relative entropy and a quantum Stein’s lemma for ergodic states and local Gibbs states. Our results provide a strong link between the abstract resource theory of thermodynamics and more realistic physical systems as we achieve a robust and operational characterization of the emergence of a thermodynamic potential in translation-invariant lattice systems

    Kondo Effect and Surface-State Electrons

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    We have used low temperature scanning tunneling spectroscopy and atomic manipulation to study the role of surface-state electrons in the Kondo effect of an isolated cobalt atom adsorbed on Ag(111). We show that the observed Kondo signature remains unchanged in close proximity of a monoatomic step, where the local density of states of the surface-state electrons is strongly perturbed. This result indicates a minor role for surface-state electrons in the Kondo effect of cobalt, compared to bulk electrons. A possible explanation for our findings is presented.Comment: 4 pages, 4 figures, ACSIN-7 proceeding

    Fontes de nitrogênio e técnicas de propagação de mudas atuam na produtividade de erva-mate.

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    Avaliou-se a influência de fontes de nitrogênio e técnicas de propagação na produtividade de erva-mate. Em plantio realizado em 2005 em São Mateus do Sul-PR (SMS), no espaçamento 1,2 x 3,0 m com mudas propagadas: por semente (procedência SMS) e por miniestaquia (procedências Bituruna, Cruz Machado e SMS). Em 2010, após a segunda colheita aplicou-se 130 kg ha-1 de nitrogênio na forma de nitrato de amônio, sulfato de amônio e ureia. Na colheita de 2012, com intervalo de 18 meses, quantificou-se a produtividade de erva-mate comercial, galho fino e galho grosso. A produtividade de todos os componentes avaliados foi influenciada pela interação entre fontes de N e procedências. Conclui-se que a preferência da erva-mate pela fonte de nitrogênio é dependente do local de origem da cultura; a miniestaquia é uma técnica eficiente na propagação de erva-mate, recomendada para melhorar a produtividade da cultura

    Propagation of a hole on a Neel background

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    We analyze the motion of a single hole on a N\'eel background, neglecting spin fluctuations. Brinkman and Rice studied this problem on a cubic lattice, introducing the retraceable-path approximation for the hole Green's function, exact in a one-dimensional lattice. Metzner et al. showed that the approximationalso becomes exact in the infinite-dimensional limit. We introduce a new approach to this problem by resumming the Nagaoka expansion of the propagator in terms of non-retraceable skeleton-paths dressed by retraceable-path insertions. This resummation opens the way to an almost quantitative solution of the problemin all dimensions and, in particular sheds new light on the question of the position of the band-edges. We studied the motion of the hole on a double chain and a square lattice, for which deviations from the retraceable-path approximation are expected to be most pronounced. The density of states is mostly adequately accounted for by the retra\-ce\-able-path approximation. Our band-edge determination points towards an absence of band tails extending to the Nagaoka energy in the spectrums of the double chain and the square lattice. We also evaluated the spectral density and the self-energy, exhibiting k-dependence due to finite dimensionality. We find good agreement with recent numerical results obtained by Sorella et al. with the Lanczos spectra decoding method. The method we employ enables us to identify the hole paths which are responsible for the various features present in the density of states and the spectral density.Comment: 26 pages,Revte

    Increased Matrix Metalloproteinase-2 and Bone Sialoprotein Response to Human Coronal Caries

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    It has been suggested that host matrix metalloproteinase-2 (MMP-2) present in dentin may be involved in caries progression, however, its response to caries is not known. Bone sialoprotein (BSP) has been implicated in dentin mineralization and MMP-2 modulation

    Uncertainty Relation Revisited from Quantum Estimation Theory

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    By invoking quantum estimation theory we formulate bounds of errors in quantum measurement for arbitrary quantum states and observables in a finite-dimensional Hilbert space. We prove that the measurement errors of two observables satisfy Heisenberg's uncertainty relation, find the attainable bound, and provide a strategy to achieve it.Comment: manuscript including 4 pages and 2 figure

    Graviton Propagators on Fuzzy G/H

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    We describe closed string modes by open Wilson lines in noncommutative (NC) gauge theories on compact fuzzy G/H in IIB matrix model. In this construction the world sheet cut-off is related to the spacetime cut-off since the string bit of the symmetric traced Wilson line carries the minimum momentum on G/H. We show that the two point correlation functions of graviton type Wilson lines in 4 dimensional NC gauge theories behave as 1/(momentum)^2. This result suggests that graviton is localized on D3-brane, so we can naturally interpret D3-branes as our universe. Our result is not limited to D3-brane system, and we generalize our analysis to other dimensions and even to any topology of D-brane worldvolume within fuzzy G/H.Comment: 22 pages, 1 figure. minor correction

    On Quartet Superfluidity of Fermionic Atomic Gas

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    Possibility of a quartet superfluidity in fermionic systems is studied as a new aspect of atomic gas at ultra low temperatures. The four-fold degeneracy of hyperfine state and moderate coupling is indispensable for the quartet superfluidity to occur. Possible superconductivity with quartet condensation in electron systems is discussed.Comment: 7 pages, 1 figure. J. Phys. Soc. Jpn. vol.74 (2005) No.7, in press; Note added for related previous works; some typographic errors revise

    Asymptotic Reversibility of Thermal Operations for Interacting Quantum Spin Systems via Generalized Quantum Stein's Lemma

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    For quantum spin systems in any spatial dimension with a local, translation-invariant Hamiltonian, we prove that asymptotic state convertibility from a quantum state to another one by a thermodynamically feasible class of quantum dynamics, called thermal operations, is completely characterized by the Kullback-Leibler (KL) divergence rate, if the state is translation-invariant and spatially ergodic. Our proof consists of two parts and is phrased in terms of a branch of the quantum information theory called the resource theory. First, we prove that any states, for which the min and max Rényi divergences collapse approximately to a single value, can be approximately reversibly converted into one another by thermal operations with the aid of a small source of quantum coherence. Second, we prove that these divergences collapse asymptotically to the KL divergence rate for any translation-invariant ergodic state. We show this via a generalization of the quantum Stein's lemma for quantum hypothesis testing beyond independent and identically distributed (i.i.d.) situations. Our result implies that the KL divergence rate serves as a thermodynamic potential that provides a complete characterization of thermodynamic convertibility of ergodic states of quantum many-body systems in the thermodynamic limit, including out-of-equilibrium and fully quantum situations
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