27,659 research outputs found
Coupled ion - nanomechanical systems
We study ions in a nanotrap, where the electrodes are nanomechanical
resonantors. The ions play the role of a quantum optical system which acts as a
probe and control, and allows entanglement with or between nanomechanical
resonators.Comment: 4 pages, 2 figures, submitted for publicatio
Effect of inelastic collisions on multiphonon Raman scattering in graphene
We calculate the probabilities of two- and four-phonon Raman scattering in
graphene and show how the relative intensities of the overtone peaks encode
information about relative rates of different inelastic processes electrons are
subject to. If the most important processes are electron-phonon and
electron-electron scattering, the rate of the latter can be deduced from the
Raman spectra
HST/FOS Eclipse mapping of IP Pegasi in outburst
We report the results of a time-resolved eclipse mapping of the dwarf nova IP
Pegasi during the decline of its May 1993 outburst from HST/FOS fast
spectroscopy covering 3 eclipses in the ultraviolet spectral range.Comment: 1 page 0 figure
Plasmon dispersion in semimetallic armchair graphene nanoribbons
The dispersion relations for plasmons in intrinsic and extrinsic semimetallic
armchair graphene nanoribbons (acGNR) are calculated in the random phase
approximation using the orthogonal p_z-orbital tight binding method. Our model
predicts new plasmons for acGNR of odd atomic widths N=5,11,17,... Our model
further predicts plasmons in acGNR of even atomic width N=2,8,14,... related to
those found using a Dirac continuum model, but with different quantitative
dispersion characteristics. We find that the dispersion of all plasmons in
semimetallic acGNR depends strongly on the localization of the p_z electronic
wavefunctions. We also find that overlap integrals for acGNR behave in a more
complex way than predicted by the Dirac continuum model, suggesting that these
plasmons will experience a small damping for all q not equal to 0. Plasmons in
extrinsic semimetallic acGNR with the chemical potential in the lowest
(highest) conduction (valence) band are found to have dispersion
characteristics nearly identical to their intrinsic counterparts, with
negligible differencs in dispersion arising from the slight differences in
overlap integrals for the interband and intraband transitions.Comment: 8 pages, 9 figure
Intersecting D-brane states derived from the KP theory
A general scheme to find tachyon boundary states is developed within the
framework of the theory of KP hierarchy. The method is applied to calculate
correlation function of intersecting D-branes and rederived the results of our
previous works as special examples. A matrix generalization of this scheme
provides a method to study dynamics of coincident multi D-branes.Comment: 10 page
Aharanov-Bohm effect for the edge states of zigzag carbon nanotubes
Two delocalized states of metallic zigzag carbon nanotubes near the Dirac
point can be localized by the Aharanov-Bohm magnetic field around 20 Tesla. The
dependence of the localization on the length and diameter of the nanotubes
shows that the localization-delocalization transition can be observed for 2 nm
diameter tube. The mechanism of the localization is explained in terms of the
deformation-induced gauge field, which shows a topological nature of the
localization. The transition from the delocalized states to the localized
states can be observed by scanning tunneling microscopy and spectroscopy. A
similarity between the transition and the spin Hall effect is discussed.Comment: 7 pages, 4 figure
Stabilization mechanism of edge states in graphene
It has been known that edge states of a graphite ribbon are zero-energy,
localized eigen-states. We show that next nearest-neighbor hopping process
decreases the energy of the edge states at zigzag edge with respect to the
Fermi energy. The energy reduction of the edge states is calculated
analytically by first-order perturbation theory and numerically. The resultant
model is consistent with the peak of recent scanning tunneling spectroscopy
measurements.Comment: 4 pages, 2 figures, final version to appear in Applied Physics
Letter
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