122,897 research outputs found
The Deuteron Spin Structure Functions in the Bethe-Salpeter Approach and the Extraction of the Neutron Structure Function
The nuclear effects in the spin-dependent structure functions and
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,
, 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
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
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
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
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