Dynamics of quantum entanglement in the reservoir with memory effects

The non-Markovian dynamics of quantum entanglement is studied by the Shabani-Lidar master equation when one of entangled quantum systems is coupled to a local reservoir with memory effects. The completely positive reduced dynamical map can be constructed in the Kraus representation. Quantum entanglement decays more slowly in the non-Markovian environment. The decoherence time for quantum entanglement can be markedly increased by the change of the memory kernel. It is found out that the entanglement sudden death between quantum systems and entanglement sudden birth between the system and reservoir occur at different instants.Comment: 14 pages, 3 figure

Experimental method for biaxial tensile strength of fabrics and preliminary investigations

This paper presents a novel experimental approach to determine the biaxial strength of fabrics. A double-layer cruciform specimen was proposed based on the improvement of previous test specimen. The design and manufacture process of the novel specimen was described in detail. Uniaxial and biaxial tests of a specific material were performed subsequently. Based on numerical simulation, the biaxial strength of the fabrics was preliminary investigated. And the correlation between uniaxial and biaxial strength of the material was discussed. The proposed experiments could characterize the biaxial strength of fabrics, and the biaxial strength of the fabrics at 1:1 tension is higher than the weft strength and little lower than the warp strength

Dynamic transition in driven vortices across the peak effect in superconductors

We study the zero-temperature dynamic transition from the disordered flow to an ordered flow state in driven vortices in type-II superconductors. The transition current $I_{p}$ is marked by a sharp kink in the $V(I)$ characteristic with a concomitant large increase in the defect concentration. On increasing magnetic field $B$, the $I_{p}(B)$ follows the behaviour of the critical current $I_{c}(B)$. Specifically, in the peak effect regime $I_{p}(B)$ increases rapidly along with $I_{c}$. We also discuss the effect of varying disorder strength on $I_{p}$.Comment: 4 pages, 4 figure

Boundary of two mixed Bose-Einstein condensates

The boundary of two mixed Bose-Einstein condensates interacting repulsively was considered in the case of spatial separation at zero temperature. Analytical expressions for density distribution of condensates were obtained by solving two coupled nonlinear Gross-Pitaevskii equations in cases corresponding weak and strong separation. These expressions allow to consider excitation spectrum of a particle confined in the vicinity of the boundary as well as surface waves associated with surface tension.Comment: 6 pages, 3 figures, submitted to Phys.Rev.

Critical depinning force and vortex lattice order in disordered superconductors

We simulate the ordering of vortices and its effects on the critical current in superconductors with varied vortex-vortex interaction strength and varied pinning strengths for a two-dimensional system. For strong pinning the vortex lattice is always disordered and the critical depinning force only weakly increases with decreasing vortex-vortex interactions. For weak pinning the vortex lattice is defect free until the vortex-vortex interactions have been reduced to a low value, when defects begin to appear with a simultaneous rapid increase in the critical depinning force. In each case the depinning force shows a maximum for non-interacting vortices. The relative height of the peak increases and the peak width decreases for decreasing pinning strength in excellent agreement with experimental trends associated with the peak effect. We show that scaling relations exist between the distance between defects in the vortex lattice and the critical depinning force.Comment: 5 pages, 6 figure

Development of a near-real-time global in situ daily precipitation dataset for 0000–0000 UTC

In this study, we have developed a global in situ daily precipitation dataset based on quasi-real-time sub-daily observations of precipitation totals for the 0000–0000 UTC (Co-ordinated Universal Time) day everywhere in the world. The sub-daily precipitation data from meteorological stations are obtained via the World Meteorological Organization's (WMO) Global Telecommunication System (GTS) and China Meteorological Administration Net (CMANet) archived by the National Meteorological Information Centre (NMIC) in China and the Integrated Surface Database (ISD) released by the National Centers for Environmental Information (NCEI) in the USA. We have combined these three sources into a global dataset, referred to as NMIC. Accumulated precipitation totals (depending on the country and the WMO region) are transmitted at a variety of times on the GTS. Of these, about 4,500 stations report daily for the 0000–0000 UTC day. Here, we significantly add to this, by developing two-way accumulation algorithms to decompose other reported sub-daily totals to shorter intervals, and then re-cumulate them where possible to the 0000–0000 UTC day. Using these algorithms, we increase by 51.1% of the number of stations during 2009–2016 to around 6,800 day−1. Additionally, date boundary adjustment (sliding between 1 and 6 hours either side of 0000 UTC) raises the data volume to between 7,800 and 8,700 day−1. We compare our NMIC product with the First Guess Daily (FGD) product from the Global Precipitation Climatology Centre (GPCC) and GHCN-Daily from NCEI (National Centers for Environmental Information). Root mean square differences between our NMIC and GPCC FGD products over the 2009–2016 period are around 3.4–3.7 mm·day−1 and the average consistency percentage is about 75.1–76.8%. Greater differences between NMIC and GHCN-daily are found which are probably due to the non-uniform date boundary in GHCN-Daily

Effects of Mn and Ti doping on superconductivity and charge ordering in NaxCoO2 system

The superconductivity in Na0.3Co1-xMxO2.1.3H2O and the charge ordering in Na0.5Co1-xMxO2 have been investigated for M = Mn and Ti substituting for Co. We have first successfully synthesized the single-phase Na0.7Co1-xMxO2(M= Mn and Ti) materials with 0 < = x < = 0.1, then we obtained Na0.5Co1-xMxO2 (0 < = x < = 0.1, M = Mn and Ti) by Na deintercalation and Na0.3Co1-xMxO2.1.3H2O (0 < = x < = 0.1, M = Mn and Ti) by an additional water intercalations. X-ray diffraction measurements revealed that all samples are single-phase materials, their lattice parameters depend systematically on the Ti and Mn contents. Measurements of physical properties indicate that the superconductivity in Na0.3Co1-xMxO2.1.3H2O is suppressed evidently by Co-site doping and killed at x = 0.02 for Mn doping and x = 0.01 for Ti doping. Charge ordering and magnetic properties in Na0.5Co1-xMxO2 were also influenced by M-atom doping.Comment: 22 pages, 3 tables, and 6 figure

Metastability and Transient Effects in Vortex Matter Near a Decoupling Transition

We examine metastable and transient effects both above and below the first-order decoupling line in a 3D simulation of magnetically interacting pancake vortices. We observe pronounced transient and history effects as well as supercooling and superheating between the 3D coupled, ordered and 2D decoupled, disordered phases. In the disordered supercooled state as a function of DC driving, reordering occurs through the formation of growing moving channels of the ordered phase. No channels form in the superheated region; instead the ordered state is homogeneously destroyed. When a sequence of current pulses is applied we observe memory effects. We find a ramp rate dependence of the V(I) curves on both sides of the decoupling transition. The critical current that we obtain depends on how the system is prepared.Comment: 10 pages, 15 postscript figures, version to appear in PR

1/f noise in a dilute GaAs two-dimensional hole system in the insulating phase

We have measured the resistance and the 1/f resistance noise of a two-dimensional low density hole system in a high mobility GaAs quantum well at low temperature. At densities lower than the metal-insulator transition one, the temperature dependence of the resistance is either power-like or simply activated. The noise decreases when the temperature or the density increase. These results contradict the standard description of independent particles in the strong localization regime. On the contrary, they agree with the percolation picture suggested by higher density results. The physical nature of the system could be a mixture of a conducting and an insulating phase. We compare our results with those of composite thin films.Comment: 4 pages, 3 figures; to appear in Physica E (EP2DS-16 proceedings

Boundary energy of the general open XXZ chain at roots of unity

We have recently proposed a Bethe Ansatz solution of the open spin-1/2 XXZ quantum spin chain with general integrable boundary terms (containing six free boundary parameters) at roots of unity. We use this solution, together with an appropriate string hypothesis, to compute the boundary energy of the chain in the thermodynamic limit.Comment: 22 pages, 6 figures; v2: some comments, a reference and a footnote adde