36,755 research outputs found

    Generation and complete nondestructive analysis of hyperentanglement assisted by nitrogen-vacancy centers in resonators

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    We present two efficient schemes for the deterministic generation and the complete nondestructive analysis of hyperentangled Bell states in both the polarization and spatial-mode degrees of freedom (DOFs) of two-photon systems, assisted by the nitrogen-vacancy (NV) centers in diamonds coupled to microtoroidal resonators as a result of cavity quantum electrodynamics (QED). With the input-output process of photons, two-photon polarization-spatial hyperentangled Bell states can be generated in a deterministic way and their complete nondestructive analysis can be achieved. These schemes can be generalized to generate and analyze hyperentangled Greenberger-Horne-Zeilinger states of multi-photon systems as well. Compared with previous works, these two schemes relax the difficulty of their implementation in experiment as it is not difficult to obtain the π\pi phase shift in single-sided NV-cavity systems. Moreover, our schemes do not require that the transmission for the uncoupled cavity is balanceable with the reflectance for the coupled cavity. Our calculations show that these schemes can reach a high fidelity and efficiency with current technology, which may be a benefit to long-distance high-capacity quantum communication with two DOFs of photon systems

    Supernova {\beta}^- decay of nuclides 53Fe, 54Fe, 55Fe, and 56Fe in strongly screened plasma

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    The electron screening strong effect on the electron energy and threshold energy of the beta decay reaction. in this paper, we study the β\beta^- decay rates of some iron isotopes. The electron screening beta decay rates increase by about two orders of magnitude. The strong screening beta decay rates due to Q-value correction are by more than one order of magnitude higher than those of without Q-value correction.Comment: 10 pages, 45 figures, accepted for publication in Resarch in Astronomy and Astrophysic

    Proximity effect can induce the energy gap rather than superconducting pair potential

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    For an s-wave superconductor/semiconductor/ferromagnetic-insulator structure, the proximity effect can induce the energy gap in the semiconductor rather than the superconducting pair potential of its microscope Hamiltonian. As a result, it is questionable to realize topological superconducting states in that structure

    The Minimal Position of a Stable Branching Random Walk

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    In this paper, a branching random walk (V(x))(V(x)) in the boundary case is studied, where the associated one dimensional random walk is in the domain of attraction of an α\alpha-stable law with 1<α<21<\alpha<2. Let MnM_n be the minimal position of (V(x))(V(x)) at generation nn. We established an integral test to describe the lower limit of Mn1αlognM_n-\frac{1}{\alpha}\log n and a law of iterated logarithm for the upper limit of Mn(1+1α)lognM_n-(1+\frac{1}{\alpha})\log n

    Partial-fraction Expansion of Lossless Negative Imaginary Property and A Generalized Lossless Negative Imaginary Lemma

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    This paper studies a partial-fraction expansion for lossless negative imaginary systems and presents a generalized lossless negative imaginary lemma by allowing poles at zero. First, a necessary and sufficient condition for a system to be non-proper lossless negative imaginary is developed, and a minor partial-fraction expansion of lossless negative imaginary property is studied. Second, according to the minor decomposition properties, two different and new relationships between lossless positive real and lossless negative imaginary systems are established. Third, according to one of the relationships, a generalized lossless negative imaginary lemma in terms of a minimal state-space realization is derived by allowing poles at zero. Some important properties of lossless negative imaginary systems are also studied in this paper, and three numerical examples are provided to illustrate the developed theor

    On 3-extra connectivity of k-ary n-cubes

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    Given a graph G, a non-negative integer h and a set of vertices S, the h-extra connectivity of G is the cardinality of a minimum set S such that G-S is disconnected and each component of G-S has at least h+1 vertices. The 2-extra connectivity of k-ary n-cube is gotten by Hsieh et al. in [Theoretical Computer Science, 443 (2012) 63-69]. In this paper, we obtained the h-extra connectivity of the k-ary n-cube networks for h=3.Comment: This paper has been withdrawn by the author due to a crucial sign error in the main theore

    The effect of the chiral chemical potential on the chiral phase transition in the NJL model with different regularization schemes

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    We study the chiral phase transition in the presence of the chiral chemical potential μ5\mu_5 using the two-flavor Nambu--Jona-Lasinio model. In particular, we analyze the reason why one can obtain two opposite behaviors of the chiral critical temperature as a function of μ5\mu_5 in the framework of different regularization schemes. We compare the modifications of the chiral condensate and the critical temperature due to μ5\mu_5 in different regularization schemes, analytically and numerically. Finally, we find that, for the conventional hard-cutoff regularization scheme, the increasing dependence of the critical temperature on the chiral chemical potential is an artifact, which is caused by the fact that it does not include complete contribution from the thermal fluctuations. When the thermal contribution is fully taken into account, the chiral critical temperature should decrease with μ5\mu_5.Comment: 11 pages, 7 figure

    Survival of charged rho condensation at high temperature and density

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    The charged vector ρ\rho mesons in the presence of external magnetic fields at finite temperature TT and chemical potential μ\mu have been investigated in the framework of the Nambu--Jona-Lasinio model. We compute the masses of charged ρ\rho mesons numerically as a function of the magnetic field for different values of temperature and chemical potential. The self-energy of the ρ\rho meson contains the quark-loop contribution, i.e. the leading order contribution in 1/Nc1/N_c expansion. The charged ρ\rho meson mass decreases with the magnetic field and drops to zero at a critical magnetic field eBceB_c, which means that the charged vector meson condensation, i.e. the electromagnetic superconductor can be induced above the critical magnetic field. Surprisingly, it is found that the charged ρ\rho condensation can even survive at high temperature and density. At zero temperature, the critical magnetic field just increases slightly with the chemical potential, which indicates that the charged ρ\rho condensation might occur inside compact stars. At zero density, in the temperature range 0.20.5 GeV0.2-0.5~ {\rm GeV}, the critical magnetic field for charged ρ\rho condensation is in the range of 0.20.6 GeV20.2-0.6~ {\rm GeV}^2, which indicates that the high temperature electromagnetic superconductor could be created at LHC

    Charged and neutral vector meson under magnetic field

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    The vector meson ρ\rho in the presence of external magnetic field has been investigated in the framework of the Nambu--Jona-Lasinio model, where mesons are constructed by infinite sum of quark-loop chains by using random phase approximation. The ρ\rho meson polarization function is calculated to the leading order of 1/Nc1/N_c expansion. It is found that the constituent quark mass increases with magnetic field, the masses of the neutral vector meson ρ0\rho^{0} with spin component sz=0,±1s_z=0,\,\pm1 and the charged vector meson ρ±\rho^{\pm} with sz=0s_z=0 also increases with magnetic field. However, the mass square of the charged vector meson ρ+\rho^{+} (ρ\rho^{-}) with sz=+1s_z=+1 (sz=1s_z=-1) decreases linearly with magnetic field and drops to zero at the critical magnetic field eBc0.2GeV2e B_c \simeq 0.2 {\rm GeV}^2, which indicates the possible condensation of charged vector meson in the vacuum. This critical magnetic field is much lower than the value eBc=0.6GeV2eB_c=0.6 {\rm GeV}^2 predicted by a point-like vector meson. We also show that if we use lowest Landau level approximation, the mass of the charged vector meson ρ±\rho^{\pm} for sz=±1s_z=\pm1 cannot drop to zero at high magnetic fields.Comment: 10 pages, 8 figure

    Scalable SUM-Shrinkage Schemes for Distributed Monitoring Large-Scale Data Streams

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    In this article, motivated by biosurveillance and censoring sensor networks, we investigate the problem of distributed monitoring large-scale data streams where an undesired event may occur at some unknown time and affect only a few unknown data streams. We propose to develop scalable global monitoring schemes by parallel running local detection procedures and by combining these local procedures together to make a global decision based on SUM-shrinkage techniques. Our approach is illustrated in two concrete examples: one is the nonhomogeneous case when the pre-change and post-change local distributions are given, and the other is the homogeneous case of monitoring a large number of independent N(0,1)N(0,1) data streams where the means of some data streams might shift to unknown positive or negative values. Numerical simulation studies demonstrate the usefulness of the proposed schemes.Comment: submitted to statistica sinic
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