601 research outputs found
Discrete surface solitons in semi-infinite binary waveguide arrays
We analyze discrete surface modes in semi-infinite binary waveguide arrays,
which can support simultaneously two types of discrete solitons. We demonstrate
that the analysis of linear surface states in such arrays provides important
information about the existence of nonlinear surface modes and their
properties. We find numerically the families of both discrete surface solitons
and nonlinear Tamm (gap) states and study their stability properties.Comment: 3 pages, 4 figures, submitted to Opt. Let
Counting Statistics and Dephasing Transition in an Electronic Mach-Zehnder Interferometer
It was recently suggested that a novel type of phase transition may occur in
the visibility of electronic Mach-Zehnder Interferometers. Here, we present
experimental evidence for the existence of this transition. The transition is
induced by strongly non-Gaussian noise that originates from the strong coupling
of a quantum point contact to the interferometer. We provide a transparent
physical picture of the effect, by exploiting a close analogy to the
neutrino-oscillations of particle physics. In addition, our experiment
constitutes a probe of the singularity of the elusive full counting statistics
of a quantum point contact.Comment: 7 pages, 4 figures (+Supplement 8 pages, 9 figures
Surface waves in mesh synthetic photonic lattices
Eigenmodes and dispersion curves in different configurations of synthetic photonic lattices are studied numerically. Eigenmodes localized on borders between areas with different optical potential are found. Stability of these eigenmodes against potential disturbances of different type is studied
Controlled generation and steering of spatial gap solitons
We demonstrate the first fully controlled generation of immobile and slow
spatial gap solitons in nonlinear periodic systems with band-gap spectra, and
reveal the key features of gap solitons which distinguish them from
conventional counterparts, including a dynamical transformation of gap solitons
due to nonlinear inter-band coupling. We also predict theoretically and confirm
experimentally the effect of anomalous steering of gap solitons in
optically-induced photonic lattices.Comment: 4 pages, 5 figure
Optical solitons in -symmetric nonlinear couplers with gain and loss
We study spatial and temporal solitons in the symmetric
coupler with gain in one waveguide and loss in the other. Stability properties
of the high- and low-frequency solitons are found to be completely determined
by a single combination of the soliton's amplitude and the gain/loss
coefficient of the waveguides. The unstable perturbations of the high-frequency
soliton break the symmetry between its active and lossy components which
results in a blowup of the soliton or a formation of a long-lived breather
state. The unstable perturbations of the low-frequency soliton separate its two
components in space blocking the power drainage of the active component and
cutting the power supply to the lossy one. Eventually this also leads to the
blowup or breathing.Comment: 14 pages, 11 figure
Edge spin accumulation in a ballistic regime
We consider a mesoscopic {\it ballistic} structure with Rashba spin-orbit
splitting of the electron spectrum. The ballistic region is attached to the
leads with a voltage applied between them. We calculate the edge spin density
which appears in the presence of a charge current through the structure due to
the difference in populations of electrons coming from different leads.
Combined effect of the boundary scattering and spin precession leads to
oscillations of the edge polarization with the envelope function decaying as a
power law of the distance from the boundary. The problem is solved with the use
of scattering states. The simplicity of the method allows to gain an insight
into the underlaying physics. We clarify the role of the unitarity of
scattering for the problem of edge spin accumulation. In case of a straight
boundary it leads to exact cancellation of all long-wave oscillations of the
spin density. As a result, only the Friedel-like spin density oscillations with
the momentum 2k_F survive. However, this appears to be rather exceptional case.
In general, the smooth spin oscillations with the spin precession length
recover, as it happens, e.g., for the wiggly boundary. We demonstrate also,
that there is no relation between the spin current in the bulk, which is zero
in the considered case, and the edge spin accumulation.Comment: Latex, 6 pages, 2 fig
Giant change in IR light transmission in La_{0.67}Ca_{0.33}MnO_{3} film near the Curie temperature: promising application in optical devices
Transport, magnetic, magneto-optical (Kerr effect) and optical (light
absorption) properties have been studied in an oriented polycrystalline
La_{0.67}Ca_{0.33}MnO_{3} film which shows colossal magneto-resistance. The
correlations between these properties are presented. A giant change in IR light
transmission (more than a 1000-fold decrease) is observed on crossing the Curie
temperature (about 270 K) from high to low temperature. Large changes in
transmittance in a magnetic field were observed as well. The giant changes in
transmittance and the large magneto-transmittance can be used for development
of IR optoelectronic devices controlled by thermal and magnetic fields.
Required material characteristics of doped manganites for these devices are
discussed.Comment: 7 pages, 7 figures, submitted to J. Appl. Phy
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