Radix-R > 2 Quantum Computation

A quantum mechanical system is presented forwhich a multiple-valued quantum algebra and logic arederivable. The system is distinguished from previousquantum computational proposals by the definition of higher order quantum algebras and logicsderived from multilevel quantum spin systems.     

Laser annealing of Bi implanted <111> and <100> silicon

The influence of surface orientation in Bi implanted silicon, annealed by Q-switched ruby laser pulse irradiation was investigated. Depth distributions and lattice location of the Bi atoms were obtained using⁴He backscattering and channeling techniques and the electrical behavior studied by sheet resistance measurements. The dopant profiles show partial surface accumulation and in-depth broadening without influence of the substrate orientation. These profiles can be fitted by a numerical calculation based on the normal freezing model with an interfacial segregation coefficient much higher than the equilibrium one. The impurity atoms located in the in-depth profile are shown to be electrically active when their maximum concentration does not exceed 10²⁰ atoms/cm³.     

2+1 gravity for genus >1

In [1] we analysed the algebra of observables for the simple case of a genus 1 initial data surface ² for 2+1 De Sitter gravity. Here we extend the analysis to higher genus. We construct for genus 2 the group of automorphismsH of the homotopy group ₁ induced by the mapping class group. The groupH induces a groupD of canonical transformations on the algebra of observables which is related to the braid group for 6 threads.     

Mössbauer studies of57Co implanted along <100> and <111> axes of Al

A significant difference in the quadrupole splittings of the weak doublet components, in the Mössbauer Spectra of⁵⁷Co implanted along <100> and <111> axes of A1, is observed. This is qualitatively explained as due to differences in defect production and recovery for implantations along these two directions.     

Temperature-pressure-induced solid-solid <100> to <110> reorientation in FCC metallic nanowire: a molecular dynamic study

Atomistic simulation of initial <100> oriented FCC Cu nanowires shows a novel coupled temperature-pressure dependent reorientation from <100> to <110> phase. A temperature-pressure-induced solid-solid <100> to <110> reorientation diagram is generated for Cu nanowire with varying cross-sectional sizes. A critical pressure is reported for Cu nanowires with varying cross-sectional sizes, above which an initial <100> oriented nanowire shows temperature independent reorientation into the <110> phase. The effect of surface stresses on the <100> to <110> reorientation is also studied. The results indicate that above a critical cross-sectional size for a given temperature-pressure, <100> to <110> reorientation is not possible. It is also reported here that for a given applied pressure, an increase in temperature is required for the <100> to <110> reorientation with increasing cross-sectional size of the nanowire. The temperature-pressure-induced solid-solid <100> to <110> reorientation diagram reported in the present paper could further be used as guidelines for controlling the reorientations/shape memory in nano-scale applications of FCC metallic nanowires.     

Doublet of cosmic-ray events with primary energies >1020 eV

The Telescope Array Collaboration has observed a cosmic-ray event with estimated primary energy of 1.38 × 10²⁰ eV whose arrival direction coincides [T. Abu-Zayyad et al. (Telescope Array Collaboration), arXiv:1205.5984], given the angular resolution of 1.5°, with that of an event with estimated primary energy of 1.23 × 10²⁰ eV observed by the Pierre Auger Observatory. The total number of events with energies >10²⁰ eV published by both experiments is six. I estimate the statistical significance of the doublet, which is rather weak, and point out that the arrival directions of events in the doublet coincide with the Galactic X-ray source Aql X-1.     

On Hidden Symmetries of d > 4 NHEK-N-Ad S Geometry

As well known, all higher dimensional Kerr-NUT-Ads metrics with arbitrary rotation and NUT parameters in an asymptotically Ad S spacetime have a new hidden symmetry. In this paper, we show that in the near horizon,the isometry group is enhanced to include the dilatation and special conformal transformation, and find the conformal transformation contains the cosmological constant. It is demonstrated that for near horizon extremal Kerr-NUT-Ads(NHEK-N-Ad S) only one rank-2 Killing tensor decomposes into a quadratic combination of the Killing vectors in terms of conformal group, while the others are functionally independent.     

High-resolution, >1 GHz NMR in unstable magnetic fields

Resistive or hybrid magnets can achieve substantially higher fields than those available in superconducting magnets, but their spatial homogeneity and temporal stability are unacceptable for high-resolution NMR. We show that modern stabilization and shimming technology, combined with detection of intermolecular zero-quantum coherences (iZQCs), can remove almost all of the effects of inhomogeneity and drifts, while retaining chemical shift differences and J couplings. In a 25-T electromagnet (1 kHz/s drift, 3 kHz linewidth over 1 cm(3)), iZQC detection removes >99% of the remaining inhomogeneity, to generate the first high-resolution liquid-state NMR spectra acquired at >1 GHz.     

One-Loop Feynman Diagram Zeta-Functions in T > 0 Field Theory

The Matsubara sums of Euclidean finite-temperature (T>0) field theory, over discrete energy, express the nontrivial topology of cylindrical T>0 spacetime. We explore the possibility that an individual T>0 Feynman diagram can be identified as a special value of a ζ-function or other meromorphic function, whose existence depends on the cylindrical topology. (Here “meromorphic” refers to one or more complex variables in which analytic continuation is performed.) We prove that one-loop Feynman diagrams with 0, 1, 2, 3, … external lines do indeed have an associated ζ-function. This “Feynman diagram ζ-function” is by construction a convenient tool for the regularization (dimensional or analytic) of its diagram. But the true power of the diagram ζ-function approach shows up in the straightforward derivation they provide of exact high-T series expansions of the one-loop diagrams. All Feynman diagrams which are simple products of one-loop diagrams can be analysed conveniently in this way. Diagrams which involve overlapping loops are more difficult, and are only briefly touched upon here. Scalar fields are studied in this paper. Two sequels will deal with T>0 fields having spin, and field theory on toroidal spacetimes T^N×Eⁿ, which generalizes the considerations in this paper on T>0 spacetime S¹×Eⁿ.     

<Emphasis Type="Italic">f</Emphasis>(<Emphasis Type="Italic">R</Emphasis>) Cosmology from <Emphasis Type="Italic">q</Emphasis>-theory

From a macroscopic theory of the quantum vacuum in terms of conserved relativistic charges (generically denoted by q ^(a) with label a), we have obtained, in the low-energy limit, a particular type of f(R) model relevant to cosmology. The macroscopic quantum-vacuum theory allows us to distinguish between different phenomenological f(R) models on physical grounds. The text was submitted by the authors in English.     

On the calculation of <H 2> molecular integrals

The density matrix equations of motion arising in the triplet mechanism of chemically induced electron spin polarization are solved exactly without the imposition of the Redfield approximation. It is shown that the triplet spin relaxation time occurring in the final expression is not the true relaxation time because the spectral density involved depends both on the rotational correlation time and on the quenching rate. The effective spin relaxation time differs only slightly from the true time. The equations are extended to the case where the initial triplet passes on its polarization to the secondary triplet and exact solutions for the polarizations of the latter's doublets are obtained in the form Π_B = cΠ_A; an explicit expression for c is presented. The consequences of the secondary triplet being able to pass back its polarization to the initial triplet are explored and a ‘coherence effect’ on the polarization on the first triplet's doublets is analysed.     

Discrete nature of superconducting nanochannels in the cuprate pseudogap regime at <Emphasis Type="Italic">T</Emphasis> > 200 K

Intensification of segregation processes with a decrease in the charge carrier concentration in cuprates should lead, according to the string model, to a decrease the discrete width w _ν of dominant bosonic stripes and an increase in their critical temperature T _c up to 1200 K. A comparison of the simulated results with the experimental data gives grounds to conclude that the anomalies of the electronic properties observed in the pseudogap regime of lightly dopes cuprates are most likely to be due to the formation of a metastable network of superconducting nanochannels with T _c > 200 K from the bosonic stripes limited by w _ν ≤ 2 nm.     

Ferromagnetism and ferroelectricity in Eu<Emphasis Type="Italic">X</Emphasis> (<Emphasis Type="Italic">X</Emphasis> = <Emphasis Type="Italic">O</Emphasis>, <Emphasis Type="Italic">S</Emphasis>): pressure effects

Ferromagnetism and ferroelectricity in Eu monochalcogenides have been investigated by ab initio density functional theory in the DFT+U approach. Exchange interaction parameters and Curie temperatures under pressure are studied and discussed using Heisenberg Hamiltonian with first and second-nearest-neighbor interactions. The calculations showed that the hydrostatic pressure perfectly improves the Curie temperature (EuO: T _C = 175 K; EuS: T _C = 33.8 K) and in the other hand it cannot induce the spontaneous polarization (P _s ). The effect of uniaxial and biaxial pressure is also studied. Although the uniaxial strains slightly increases the Curie temperature, it ensures the ferrolectricity in these systems by producing a spontaneous polarization of the order of P _s (EuO) = 57.50 μC/cm² and P _s (EuS) = 42.86 μC/cm² with pressures of 5% and 4%, respectively. The search for new model systems is a necessity to better understand the physics related to multiferroïc materials and to consider possible applications.     

Hints of theta13>0 from global neutrino data analysis

Nailing down the unknown neutrino mixing angle theta{13} is one of the most important goals in current lepton physics. In this context, we perform a global analysis of neutrino oscillation data, focusing on theta{13}, and including recent results [ (unpublished)]. We discuss two converging hints of theta{13}>0, each at the level of approximately 1sigma: an older one coming from atmospheric neutrino data, and a newer one coming from the combination of solar and long-baseline reactor neutrino data. Their combination provides the global estimate sin{2}theta{13}=0.016+/-0.010(1sigma), implying a preference for theta{13}>0 with non-negligible statistical significance ( approximately 90% C.L.). We discuss possible refinements of the experimental data analyses, which might sharpen such intriguing indications.