10,526 research outputs found
Quantum data hiding with spontaneous parameter down-conversion
Here we analyze the practical implication of the existing quantum data hiding
protocol with Bell states produced with optical downconverter. We show that the
uncertainty for the producing of the Bell states with spontaneous parameter
down-conversion should be taken into account, because it will cause serious
trouble to the hider encoding procedure. A set of extended Bell states and a
generalized Bell states analyzer are proposed to describe and analyze the
possible states of two photons distributing in two paths. Then we present a
method to integrate the above uncertainty of Bell states preparation into the
dating hiding procedure, when we encode the secret with the set of extended
Bell states. These modifications greatly simplify the hider's encoding
operations, and thus paves the way for the implementation of quantum data
hiding with present-day quantum optics.Comment: 4 pages, 1 figure, adding some analyse for security proof, to be
appear in Phys. Rev.
Influence measures in subnetworks using vertex centrality
This work deals with the issue of assessing the influence of a node in the entire network and in the subnetwork to which it belongs as well, adapting the classical idea of vertex centrality. We provide a general definition of relative vertex centrality measure with respect to the classical one, referred to the whole network. Specifically, we give a decomposition of the relative centrality measure by including also the relative influence of the single node with respect to a given subgraph containing it. The proposed measure of relative centrality is tested in the empirical networks generated by collecting assets of the S&P 100, focusing on two specific centrality indices: betweenness and eigenvector centrality. The analysis is performed in a time perspective, capturing the assets influence, with respect to the characteristics of the analysed measures, in both the entire network and the specific sectors to which the assets belong.
This is a post-peer-review, pre-copyedit version of an article published in Soft Computing. The final authenticated version is available online at: http://dx.doi.org/10.1007/s00500-019-04428-y
Dynamical Stability of an Ion in a Linear Trap as a Solid-State Problem of Electron Localization
When an ion confined in a linear ion trap interacts with a coherent laser
field, the internal degrees of freedom, related to the electron transitions,
couple to the vibrational degree of freedom of the ion. As a result of this
interaction, quantum dynamics of the vibrational degree of freedom becomes
complicated, and in some ranges of parameters even chaotic. We analyze the
vibrational ion dynamics using a formal analogy with the solid-state problem of
electron localization. In particular, we show how the resonant approximation
used in analysis of the ion dynamics, leads to a transition from a
two-dimensional (2D) to a one-dimensional problem (1D) of electron
localization. The localization length in the solid-state problem is estimated
in cases of weak and strong interaction between the cites of the 2D cell by
using the methods of resonance perturbation theory, common in analysis of 1D
time-dependent dynamical systems.Comment: 18 pages RevTe
Perturbation Theory for Quantum Computation with Large Number of Qubits
We describe a new and consistent perturbation theory for solid-state quantum
computation with many qubits. The errors in the implementation of simple
quantum logic operations caused by non-resonant transitions are estimated. We
verify our perturbation approach using exact numerical solution for relatively
small (L=10) number of qubits. A preferred range of parameters is found in
which the errors in processing quantum information are small. Our results are
needed for experimental testing of scalable solid-state quantum computers.Comment: 8 pages RevTex including 2 figure
Quantum Breaking Time Scaling in the Superdiffusive Dynamics
We show that the breaking time of quantum-classical correspondence depends on
the type of kinetics and the dominant origin of stickiness. For sticky dynamics
of quantum kicked rotor, when the hierarchical set of islands corresponds to
the accelerator mode, we demonstrate by simulation that the breaking time
scales as with the transport exponent
that corresponds to superdiffusive dynamics. We discuss also other
possibilities for the breaking time scaling and transition to the logarithmic
one with respect to
The Porphyromonas gingivalis hemagglutinins HagB and HagC are major mediators of adhesion and biofilm formation
Porphyromonas gingivalis is a bacterium associated with chronic periodontitis that possesses a family of genes encoding hemagglutinins required for heme acquisition. In this study we generated ΔhagB and ΔhagC mutants in strain W83 and demonstrate that both hagB and hagC are required for adherence to oral epithelial cells. Unexpectedly, a double ΔhagB/ΔhagC mutant had less severe adherence defects than either of the single mutants, but was found to exhibit increased expression of the gingipain-encoding genes rgpA and kgp, suggesting that a ΔhagB/ΔhagC mutant is only viable in populations of cells that exhibit increased expression of genes involved in heme acquisition. Disruption of hagB in the fimbriated strain ATCC33277 demonstrated that HagB is also required for stable attachment of fimbriated bacteria to oral epithelial cells. Mutants of hagC were also found to form defective single and multi-species biofilms that had reduced biomass relative to biofilms formed by the wild-type strain. This study highlights the hitherto unappreciated importance of these genes in oral colonization and biofilm formation
On the 3D steady flow of a second grade fluid past an obstacle
We study steady flow of a second grade fluid past an obstacle in three space
dimensions. We prove existence of solution in weighted Lebesgue spaces with
anisotropic weights and thus existence of the wake region behind the obstacle.
We use properties of the fundamental Oseen tensor together with results
achieved in \cite{Koch} and properties of solutions to steady transport
equation to get up to arbitrarily small \ep the same decay as the Oseen
fundamental solution
An optimization model for minimizing systemic risk
This paper proposes an optimal allocation model with the main aim to minimize systemic risk related to the sovereign risk of a set of countries. The reference methodological environment is that of complex networks theory. Specifically, we consider the weighted clustering coefficient as a proxy of systemic risk, while the interconnections among countries are captured by the relationships among default probabilities of the set of countries under consideration. The selected optimization criterion is based on minimization of the mean absolute deviation. We perform empirical analyses to validate the theoretical predictions, and interpret the findings in the context of the proposed model
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