19,175 research outputs found
Curvature-induced radiation of surface plasmon polaritons propagating around bends
We present a theoretical study of the curvature-induced radiation of surface
plasmon polaritons (SPPs) propagating around bends at metal-dielectric
interfaces. We explain qualitatively how the curvature leads to distortion of
the phase front, causing the fields to radiate energy away from the
metal-dielectric interface. We then quantify, both analytically and
numerically, radiation losses and energy transmission efficiencies of SPPs
propagating around bends with varying radii- as well as sign-of-curvature.Comment: 9 pages, 8 figures, submitted to Physical Review
Decoherence modes of entangled qubits within neutron interferometry
We study two different decoherence modes for entangled qubits by considering
a Liouville - von Neumann master equation. Mode A is determined by projection
operators onto the eigenstates of the Hamiltonian and mode B by projectors onto
rotated states. We present solutions for general and for Bell diagonal states
and calculate for the later the mixedness and the amount of entanglement given
by the concurrence.
We propose a realization of the decoherence modes within neutron
interferometry by applying fluctuating magnetic fields. An experimental test of
the Kraus operator decomposition describing the evolution of the system for
each mode is presented.Comment: 15 pages, 5 figure
The Spin Mass of an Electron Liquid
We show that in order to calculate correctly the {\it spin current} carried
by a quasiparticle in an electron liquid one must use an effective "spin mass"
, that is larger than both the band mass, , which determines the
charge current, and the quasiparticle effective mass , which determines
the heat capacity. We present microscopic calculations of in a
paramagnetic electron liquid in three and two dimensions, showing that the mass
enhancement can be a very significant effect.Comment: 10 pages, 1 figur
PCAC and the Deficit of Forward Muons in pi^+ Production by Neutrinos
The K2K experiment, using a fine-grained detector in a neutrino beam of
energy has observed two-track events that can be
interpreted as a coherent reaction or an incoherent process , the final nucleon being unobserved. The data show a significant
deficit of forward-going muons in the interval ,
where a sizeable coherent signal is expected. We attempt an explanantion of
this effect, using a PCAC formula that includes the effect of the non-vanishing
muon mass. A suppression of about 25 % is caused by a destructive interference
of the axial vector and pseudoscalar (pion-exchange) amplitudes. The incoherent
background is also reduced by 10 - 15 %. As a consequence the discrepancy
between theory and observation is significantly reduced.Comment: 4 pages including 1 figure, changes in abstract and text; version to
appear in Phys.Lett.
Vector modulation instability induced by vacuum fluctuations in highly birefringent fibers in the anomalous dispersion regime
We report a detailed experimental study of vector modulation instability in
highly birefringent optical fibers in the anomalous dispersion regime. We prove
that the observed instability is mainly induced by vacuum fluctuations. The
detuning of the spectral peaks agrees with linear perturbation analysis. The
exact shape of the spectrum is well reproduced by numerical integration of
stochastic nonlinear Schrodinger equations describing quantum propagation.Comment: 11 pages, 4 figures, to be published in Optics Letter
Proton Activation Analysis of Several Trace Impurities in Standard Steel Samples
開始ページ、終了ページ: 冊子体のページ付
Antiferromagnetic Vortex Core of Tl_2Ba_2CuO_{6+x} Studied by Nuclear Magnetic Resonance
Spatially-resolved NMR is used to probe the magnetism in and around vortex
cores of nearly optimally-doped Tl_2Ba_2CuO_{6+x} (Tc=85 K). The NMR relaxation
rate 1/T_1 at Tl site provides a direct evidence that the AF spin correlation
is significantly enhanced in the vortex core region. In the core region Cu
spins show a local AF ordering with moments parallel to the layers at T_N=20K.
Above T_N the core region is in the paramagnetic state which is a reminiscence
of the state above the pseudogap temperature (T*~120 K), indicating that the
pseudogap disappears within cores.Comment: 4 pages, 4 figure
Solitary Waves Bifurcated from Bloch Band Edges in Two-dimensional Periodic Media
Solitary waves bifurcated from edges of Bloch bands in two-dimensional
periodic media are determined both analytically and numerically in the context
of a two-dimensional nonlinear Schr\"odinger equation with a periodic
potential. Using multi-scale perturbation methods, envelope equations of
solitary waves near Bloch bands are analytically derived. These envelope
equations reveal that solitary waves can bifurcate from edges of Bloch bands
under either focusing or defocusing nonlinearity, depending on the signs of
second-order dispersion coefficients at the edge points. Interestingly, at edge
points with two linearly independent Bloch modes, the envelope equations lead
to a host of solitary wave structures including reduced-symmetry solitons,
dipole-array solitons, vortex-cell solitons, and so on -- many of which have
never been reported before. It is also shown analytically that the centers of
envelope solutions can only be positioned at four possible locations at or
between potential peaks. Numerically, families of these solitary waves are
directly computed both near and far away from band edges. Near the band edges,
the numerical solutions spread over many lattice sites, and they fully agree
with the analytical solutions obtained from envelope equations. Far away from
the band edges, solitary waves are strongly localized with intensity and phase
profiles characteristic of individual families.Comment: 23 pages, 15 figures. To appear in Phys. Rev.
Weak-Light Ultraslow Vector Optical Solitons via Electromagnetically Induced Transparency
We propose a scheme to generate temporal vector optical solitons in a
lifetime broadened five-state atomic medium via electromagnetically induced
transparency. We show that this scheme, which is fundamentally different from
the passive one by using optical fibers, is capable of achieving
distortion-free vector optical solitons with ultraslow propagating velocity
under very weak drive conditions. We demonstrate both analytically and
numerically that it is easy to realize Manakov temporal vector solitons by
actively manipulating the dispersion and self- and cross-phase modulation
effects of the system.Comment: 4 pages, 4 figure
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