Lower Bounds of Concurrence for Tripartite Quantum Systems

We derive an analytical lower bound for the concurrence of tripartite quantum mixed states. A functional relation is established relating concurrence and the generalized partial transpositions.Comment: 10 page

Heat transport in an open transverse-field Ising chain

The heat conduction in an open transverse-field Ising chain is studied by using quantization in the Fock space of operators in the weak coupling regimes, i.e. the coupling is much smaller than the transverse field. The non-equilibrium steady state is obtained for large size systems coupled to Markovian baths at its ends. The ballistic transport is observed in the uniform chain and normal diffusion in the random-exchange chain. {In addition, the ballistic-diffusive transition is found at the intermediate disorder regime.} The thermal conductivity $\kappa$ is also calculated in the low and high temperature regimes. It is shown that $\kappa$ decays as $\kappa\sim T^{-2}$ at high temperatures.Comment: 6 pages, 7 figure

The decay rate of ψ(2S)\psi(2S) to Λc+Σ+ˉ\Lambda_c+\bar{\Sigma^+} in SM and beyond

With rapid growth of the database of the BES III and the proposed super flavor factory, measurement on the rare $\psi(2S)$ decays may be feasible, especially the weak decays into baryon final states. In this work we study the decay rate of $\psi(2S)$ to $\Lambda_c+\overline{\Sigma^+}$ in the SM and physics beyond the SM (here we use the unparticle model as an example). The QPC model is employed to describe the creation of a pair of $q\bar q$ from vacuum. We find that the rate of $\psi(2S)\rightarrow \Lambda_c+\overline{\Sigma^+}$ is at order of $10^{-10}$ in the SM, whereas the contribution of the unparticle is too small to be substantial. Therefore if a large branching ratio is observed, it must be due to new physics beyond SM, but by no means the unparticle.Comment: 9 pages, 1 figure

A Reformulated Convex and Selective Variational Image Segmentation Model and its Fast Multilevel Algorithm

Selective image segmentation is the task of extracting one object of interest among many others in an image based on minimal user input. Two-phase segmentation models cannot guarantee to locate this object, while multiphase models are more likely to classify this object with another features in the image. Several selective models were proposed recently and they would find local minimizers (sensitive to initialization) because non-convex minimization functionals are involved. Recently, Spencer-Chen (CMS 2015) has successfully proposed a convex selective variational image segmentation model (named CDSS), allowing a global minimizer to be found independently of initialization. However, their algorithm is sensitive to the regularization parameter µ and the area parameter θ due to nonlinearity in the functional and additionally it is only effective for images of moderate size. In order to process images of large size associated with high resolution, urgent need exists in developing fast iterative solvers. In this paper, a stabilized variant of CDSS model through primal-dual formulation is proposed and an optimization based multilevel algorithm for the new model is introduced. Numerical results show that the new model is less sensitive to parameter µ and θ compared to the original CDSS model and the multilevel algorithm produces quality segmentation in optimal computational time

Hydrothermal synthesis of reduced graphene oxide-LiNi0.5Mn1.5O4 composites as 5V cathode materials for Li-ion batteries

Composite materials consisting of reduced graphene oxide and LiNi0.5Mn1.5O4 were in situ prepared by a simple one-step hydrothermal treating method. The physical property and electrochemical performance of the composite materials were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, cyclic voltammetry, charge/discharge testing, and electrochemical impedance spectroscopy. The results demonstrate that the graphene oxide is partially reduced and uniformly in situ anchored on the surface of LiNi0.5Mn1.5O4. As a result, the specific surface area of the composite material dramatically increases from 0.2488 to 8.71 m2 g−1, and the initial specific discharge capacity improves from 125.8 to 140.2 mAh g−1, respectively. Furthermore, the capacity retention maintains 95.8% after 100 cycles, and the electrode polarization has significantly been lessened. At rates of 1, 2, and 5 C, the composite material with 5% reduced graphene oxide can deliver much higher capacities than the pristine LiNi0.5Mn1.5O4. Moreover, AC impedance test results show that the interfacial charge transfer impedance obviously reduced. It is confirmed that the introduction of reduced graphene oxide through hydrothermal treating is effective to enhance the electrochemical performance of the composite material