88 research outputs found

    A mapping approach for configuration management tools to close the gap between two worlds and to regain trust: Or how to convert from docker to legacy tools (and vice versa)

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    In this paper we present the tool 'DockerConverter', an approach and a software to map a Docker configuration to various matured systems and also to reverse engineer any available Docker image in order to increase the confidence (or trust) into it. We show why a mapping approach is more promising than constructing a Domain Specific Language and why we chose a Docker image instead of the Dockerfile as the source model. Our overall goal is to enable Semantic Web research projects and especially Linked Data enterprise services to be better integrated into enterprise applications and companies

    Quantum Chaos in Open versus Closed Quantum Dots: Signatures of Interacting Particles

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    This paper reviews recent studies of mesoscopic fluctuations in transport through ballistic quantum dots, emphasizing differences between conduction through open dots and tunneling through nearly isolated dots. Both the open dots and the tunnel-contacted dots show random, repeatable conductance fluctuations with universal statistical proper-ties that are accurately characterized by a variety of theoretical models including random matrix theory, semiclassical methods and nonlinear sigma model calculations. We apply these results in open dots to extract the dephasing rate of electrons within the dot. In the tunneling regime, electron interaction dominates transport since the tunneling of a single electron onto a small dot may be sufficiently energetically costly (due to the small capacitance) that conduction is suppressed altogether. How interactions combine with quantum interference are best seen in this regime.Comment: 15 pages, 11 figures, PDF 2.1 format, to appear in "Chaos, Solitons & Fractals

    Statistical Properties of Level Widths and Conductance Peaks in a Quantum Dot

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    We study the statistics of level widths of a quantum dot with extended contacts in the absence of time-reversal symmetry. The widths are determined by the amplitude of the wavefunction averaged over the contact area. The distribution function of level widths for a two-point contact is evaluated exactly. The distribution resembles closely the result obtained when the wavefunction fluctuates independently at each point, but differs from the one-point case. Analytical calculations and numerical simulations show that the distribution for many-point contacts has a power-law behavior at small level widths. The exponent is given by the number of points in the lead and diverges in the continuous limit. The distribution of level widths is used to determine the distribution of conductance peaks in the resonance regime. At intermediate temperatures, we find that the distribution tends to normal and fluctuations in the height of the peaks are suppressed as the lead size is increased.Comment: 13 pages, RevTeX 3, six uuencoded postscript figures, CMT-ERM-940

    Pauli principle and chaos in a magnetized disk

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    We present results of a detailed quantum mechanical study of a gas of NN noninteracting electrons confined to a circular boundary and subject to homogeneous dc plus ac magnetic fields (B=Bdc+Bacf(t)(B=B_{dc}+B_{ac}f(t), with f(t+2π/ω0)=f(t)f(t+2\pi/\omega_0)=f(t)). We earlier found a one-particle {\it classical} phase diagram of the (scaled) Larmor frequency ω~c=omegac/ω0\tilde\omega_c=omega_c/\omega_0 {\rm vs} ϵ=Bac/Bdc\epsilon=B_{ac}/B_{dc} that separates regular from chaotic regimes. We also showed that the quantum spectrum statistics changed from Poisson to Gaussian orthogonal ensembles in the transition from classically integrable to chaotic dynamics. Here we find that, as a function of NN and (ϵ,ω~c)(\epsilon,\tilde\omega_c), there are clear quantum signatures in the magnetic response, when going from the single-particle classically regular to chaotic regimes. In the quasi-integrable regime the magnetization non-monotonically oscillates between diamagnetic and paramagnetic as a function of NN. We quantitatively understand this behavior from a perturbation theory analysis. In the chaotic regime, however, we find that the magnetization oscillates as a function of NN but it is {\it always} diamagnetic. Equivalent results are also presented for the orbital currents. We also find that the time-averaged energy grows like N2N^2 in the quasi-integrable regime but changes to a linear NN dependence in the chaotic regime. In contrast, the results with Bose statistics are akin to the single-particle case and thus different from the fermionic case. We also give an estimate of possible experimental parameters were our results may be seen in semiconductor quantum dot billiards.Comment: 22 pages, 7 GIF figures, Phys. Rev. E. (1999

    Universal Parametric Correlations of Conductance Peaks in Quantum Dots

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    We compute the parametric correlation function of the conductance peaks in chaotic and weakly disordered quantum dots in the Coulomb blockade regime and demonstrate its universality upon an appropriate scaling of the parameter. For a symmetric dot we show that this correlation function is affected by breaking time-reversal symmetry but is independent of the details of the channels in the external leads. We derive a new scaling which depends on the eigenfunctions alone and can be extracted directly from the conductance peak heights. Our results are in excellent agreement with model simulations of a disordered quantum dot.Comment: 12 pages, RevTex, 2 Postscript figure

    Magnetic-field dependence of energy levels in ultrasmall metal grains

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    We present a theory of mesoscopic fluctuations of g tensors and avoided crossing energies in a small metal grain. The model, based on random matrix theory, contains both the orbital and spin contributions to the g tensor. The two contributions can be experimentally separated for weak spin-orbit coupling while they merge in the strong coupling limit. For intermediate coupling, substantial correlations are found between g factors of neighboring levels.Comment: 9 pages, 5 figure

    Defining and controlling double quantum dots in single-walled carbon nanotubes

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    We report the experimental realization of double quantum dots in single-walled carbon nanotubes. The device consists of a nanotube with source and drain contact, and three additional top-gate electrodes in between. We show that, by energizing these top-gates, it is possible to locally gate a nanotube, to create a barrier, or to tune the chemical potential of a part of the nanotube. At low temperatures we find (for three different devices) that in certain ranges of top-gate voltages our device acts as a double quantum dot, evidenced by the typical honeycomb charge stability pattern.Comment: 9 pages, 3 figure

    Research-Data Management Planning in the German Mathematical Community

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    In this paper we discuss the notion of research data for the field of mathematics and report on the status quo of research-data management and planning. A number of decentralized approaches are presented and compared to needs and challenges faced in three use cases from different mathematical subdisciplines. We highlight the importance of tailoring research-data management plans to mathematicians' research processes and discuss their usage all along the data life cycle

    One-dimensional metallic behavior of the stripe phase in La2x_{2-x}Srx_xCuO4_4

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    Using an exact diagonalization method within the dynamical mean-field theory we study stripe phases in the two-dimensional Hubbard model. We find a crossover at doping δ0.05\delta\simeq 0.05 from diagonal stripes to vertical site-centered stripes with populated domain walls, stable in a broad range of doping, 0.05<δ<0.170.05<\delta<0.17. The calculated chemical potential shift δ2\propto -\delta^2 and the doping dependence of the magnetic incommensurability are in quantitative agreement with the experimental results for doped La2x_{2-x}Srx_xCuO4_4. The electronic structure shows one-dimensional metallic behavior along the domain walls, and explains the suppression of spectral weight along the Brillouin zone diagonal.Comment: 4 pages, 4 figure

    Universal Correlations of Coulomb Blockade Conductance Peaks and the Rotation Scaling in Quantum Dots

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    We show that the parametric correlations of the conductance peak amplitudes of a chaotic or weakly disordered quantum dot in the Coulomb blockade regime become universal upon an appropriate scaling of the parameter. We compute the universal forms of this correlator for both cases of conserved and broken time reversal symmetry. For a symmetric dot the correlator is independent of the details in each lead such as the number of channels and their correlation. We derive a new scaling, which we call the rotation scaling, that can be computed directly from the dot's eigenfunction rotation rate or alternatively from the conductance peak heights, and therefore does not require knowledge of the spectrum of the dot. The relation of the rotation scaling to the level velocity scaling is discussed. The exact analytic form of the conductance peak correlator is derived at short distances. We also calculate the universal distributions of the average level width velocity for various values of the scaled parameter. The universality is illustrated in an Anderson model of a disordered dot.Comment: 35 pages, RevTex, 6 Postscript figure
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