Quantum network architecture of tight-binding models with substitution sequences

We study a two-spin quantum Turing architecture, in which discrete local rotations \alpha_m of the Turing head spin alternate with quantum controlled NOT-operations. Substitution sequences are known to underlie aperiodic structures. We show that parameter inputs \alpha_m described by such sequences can lead here to a quantum dynamics, intermediate between the regular and the chaotic variant. Exponential parameter sensitivity characterizing chaotic quantum Turing machines turns out to be an adequate criterion for induced quantum chaos in a quantum network.Comment: Accepted for publication in J. mod. Optics [Proc. Workshop "Entanglement and Decoherence", Gargnano (Italy), Sept 1999], 3 figure

Local minimality of the volume-product at the simplex

It is proved that the simplex is a strict local minimum for the volume product, P(K)=min(vol(K) vol(K^z)), K^z is the polar body of K with respect to z, the minimum is taken over z in the interior of K, in the Banach-Mazur space of n-dimensional (classes of ) convex bodies. Linear local stability in the neighborhood of the simplex is proved as well. The proof consists of an extension to the non-symmetric setting of methods that were recently introduced by Nazarov, Petrov, Ryabogin and Zvavitch, as well as proving results of independent interest, concerning stability of square order of volumes of polars of non-symmetric convex bodies.Comment: Mathematika, accepte

The COST IRACON Geometry-based Stochastic Channel Model for Vehicle-to-Vehicle Communication in Intersections

Vehicle-to-vehicle (V2V) wireless communications can improve traffic safety at road intersections and enable congestion avoidance. However, detailed knowledge about the wireless propagation channel is needed for the development and realistic assessment of V2V communication systems. We present a novel geometry-based stochastic MIMO channel model with support for frequencies in the band of 5.2-6.2 GHz. The model is based on extensive high-resolution measurements at different road intersections in the city of Berlin, Germany. We extend existing models, by including the effects of various obstructions, higher order interactions, and by introducing an angular gain function for the scatterers. Scatterer locations have been identified and mapped to measured multi-path trajectories using a measurement-based ray tracing method and a subsequent RANSAC algorithm. The developed model is parameterized, and using the measured propagation paths that have been mapped to scatterer locations, model parameters are estimated. The time variant power fading of individual multi-path components is found to be best modeled by a Gamma process with an exponential autocorrelation. The path coherence distance is estimated to be in the range of 0-2 m. The model is also validated against measurement data, showing that the developed model accurately captures the behavior of the measured channel gain, Doppler spread, and delay spread. This is also the case for intersections that have not been used when estimating model parameters.Comment: Submitted to IEEE Transactions on Vehicular Technolog

Uncertainty rescued: Bohr's complementarity for composite systems

Generalized uncertainty relations may depend not only on the commutator relation of two observables considered, but also on mutual correlations, in particular, on entanglement. The equivalence between the uncertainty relation and Bohr's complementarity thus holds in a much broader sense than anticipated.Comment: Accepted for publication in Phys. Lett.

Protein phosphorylation in yeast mitochondria

We describe the identification and submitochondrial localization of four protein kinases and of their target proteins in derepressed yeast mitochondria. The activity of one of the kinases depends on the presence of cyclic AMP (cAMP). It is soluble and localized in the mitochondrial intermembrane space. Its natural target is a polypeptide of 40 kDa molecular mass, which is bound to the inner membrane. Besides this natural target this kinase phosphorylates acidic heterologous proteins, like casein, with high efficiency. The other protein kinases identified so far are cAMP-independent. At least one is localized in the matrix having its natural substrates (49 and 24 kDa) in the same compartment. Two others are firmly bound to the inner membrane phosphorylating target proteins in the inner membrane (52·5 kDa) and in the intermembrane space (17·5 kDa), respectively

Quantum chaos in quantum Turing machines

We investigate a 2-spin quantum Turing architecture, in which discrete local rotations \alpha_m of the Turing head spin alternate with quantum controlled NOT-operations. We demonstrate that a single chaotic parameter input \alpha_m leads to a chaotic dynamics in the entire Hilbert-space.Comment: Accepted for publication in Phys. Lett. A, 3 figure