The Deuteron Spin Structure Functions in the Bethe-Salpeter Approach and the Extraction of the Neutron Structure Function g1n(x)g_1^n(x)

The nuclear effects in the spin-dependent structure functions $g_1^D$ and $b_2^D$ are calculated in the relativistic approach based on the Bethe-Salpeter equation with a realistic meson-exchange potential. The results of calculations are compared with the non-relativistic calculations. The problem of extraction of the neutron spin structure function, $g_1^n$, from the deuteron data is discussed.Comment: (Talk given at the SPIN'94 International Symposium, September 15-22, 1994, Bloomington, Indiana), 6 pages, 5 figures, Preprint Alberta Thy 29-9

Coupling Josephson qubits via a current-biased information bus

Josephson qubits without direct interaction can be effectively coupled by sequentially connecting them to an information bus: a current-biased large Josephson junction treated as an oscillator with adjustable frequency. The coupling between any qubit and the bus can be controlled by modulating the magnetic flux applied to that qubit. This tunable and selective coupling provides two-qubit entangled states for implementing elementary quantum logic operations, and for experimentally testing Bell's inequality.Comment: 10 pages, 1 figure. submitte

Hybrid superconducting quantum magnetometer

A superconducting quantum magnetometer based on magnetic flux-driven modulation of the density of states of a proximized metallic nanowire is theoretically analyzed. With optimized geometrical and material parameters transfer functions up to a few mV/Phi_0 and intrinsic flux noise ~10^{-9}Phi_0 Hz^{-1/2} below 1 K are achievable. The opportunity to access single-spin detection joined with limited dissipation (of the order of ~ 10^{-14} W) make this magnetometer interesting for the investigation of the switching dynamics of molecules or individual magnetic nanoparticles.Comment: 6 pages, 6 color figures, added calculation of the Josephson current, published versio

Matrix Model Calculations beyond the Spherical Limit

We propose an improved iterative scheme for calculating higher genus contributions to the multi-loop (or multi-point) correlators and the partition function of the hermitian one matrix model. We present explicit results up to genus two. We develop a version which gives directly the result in the double scaling limit and present explicit results up to genus four. Using the latter version we prove that the hermitian and the complex matrix model are equivalent in the double scaling limit and that in this limit they are both equivalent to the Kontsevich model. We discuss how our results away from the double scaling limit are related to the structure of moduli space.Comment: 44 page

Realistic interatomic potential for MD simulations

The coefficients of interatomic potential of simple form Exp-6 for neon are obtained. Repulsive part is calculated ab-initio in the Hartree-Fock approximation using the basis of atomic orbitals orthogonalized exactly on different lattice sites. Attractive part is determined empirically using single fitting parameter. The potential obtained describes well the equation of state and elastic moduli of neon crystal in wide range of interatomic distances and it is appropriate for molecular dynamic simulations of high temperature properties and phenomena in crystals and liquids.Comment: MikTex v.2.1 (AMS-TEX),11 pages, 3 EPS figure

Curvature-induced symmetry breaking in nonlinear Schrodinger models

We consider a curved chain of nonlinear oscillators and show that the interplay of curvature and nonlinearity leads to a symmetry breaking when an asymmetric stationary state becomes energetically more favorable than a symmetric stationary state. We show that the energy of localized states decreases with increasing curvature, i.e. bending is a trap for nonlinear excitations. A violation of the Vakhitov-Kolokolov stability criterium is found in the case where the instability is due to the softening of the Peierls internal mode.Comment: 4 pages (LaTex) with 6 figures (EPS

NMR evidence of strong-correlated superconductivity in LiFeAs: tuning toward an SDW ordering

In this letter, we reported the results of NMR study on LiFeAs single crystals. We find a strong evidence of the low temperature spin fluctuations; by changing sample preparation conditions, the system can be tuned toward an spin-density-wave (SDW) quantum-critical point. The detection of an interstitial Li(2) ion, possibly locating in the tetrahedral hole, suggests that the off-stoichiometry and/or lattice defect can probably account for the absence of the SDW ordering in LiFeAs. These facts show that LiFeAs is a strongly correlated system and the superconductivity is likely originated from the SDW fluctuations.Comment: 5 pages, s figure

Edge and waveguide THz surface plasmon modes in graphene micro-ribbons

Surface plasmon modes supported by graphene ribbon waveguides are studied and classified. The properties of both modes with the field concentration within the ribbon area (waveguiding modes) and on the edges (edge modes) are discussed. The waveguide and edge modes are shown to be separated from each other by a gap in wavenumbers. The even-parity hybridized edge mode results to be the fundamental electromagnetic mode of the ribbon, possessing also the lowest losses. All the plasmonic modes in the ribbons have an optimum frequency, at which the absorption losses are minimum, due to competition between the plasmon confinement and the frequency dependence of absorption in graphene.Comment: 4 pages, 4 figure