285 research outputs found
Constraints on transmission, dispersion, and density of states in dielectric multilayers and stepwise potential barriers with arbitrary layer arrangement
Normal-incidence transmission and dispersion properties of optical
multilayers and one-dimensional stepwise potential barriers in the
non-tunneling regime are analytically investigated. The optical paths of every
constituent layer in a multilayer structure, as well as the parameters of every
step of the stepwise potential barrier, are constrained by a generalized
quarter-wave condition. No other restrictions on the structure geometry is
imposed, i.e., the layers are arranged arbitrarily. We show that the density of
states (DOS) spectra of the multilayer or barrier in question are subject to
integral conservation rules similar to the Barnett-Loudon sum rule but ocurring
within a finite frequency or energy interval. In the optical case, these
frequency intervals are regular. For the potential barriers, only non-periodic
energy intervals can be present in the spectrum of any given structure, and
only if the parameters of constituent potential steps are properly chosen.
Abstract The integral conservation relations derived analytically have also
been verified numerically. The relations can be used in dispersion-engineered
multilayer-based devices, e.g., ultrashort pulse compressors or ultracompact
optical delay lines, as well as to design multiple-quantum-well electronic
heterostructures with engineered DOS.Comment: 10 pages, 5 figures, to be submitted to PR
Non-abelian plane waves and stochastic regimes for (2+1)-dimensional gauge field models with Chern-Simons term
An exact time-dependent solution of field equations for the 3-d gauge field
model with a Chern-Simons (CS) topological mass is found. Limiting cases of
constant solution and solution with vanishing topological mass are considered.
After Lorentz boost, the found solution describes a massive nonlinear
non-abelian plane wave. For the more complicate case of gauge fields with CS
mass interacting with a Higgs field, the stochastic character of motion is
demonstrated.Comment: LaTeX 2.09, 13 pages, 11 eps figure
Hyperentangled photon sources in semiconductor waveguides
We propose and analyze the performance of a technique to generate mode and polarization hyperentangled photons in monolithic semiconductor waveguides using two concurrent type-II spontaneous parametric down-conversion (SPDC) processes. These two SPDC processes are achieved by waveguide engineering which allows for simultaneous modal phase matching with the pump beam in a higher-order mode. Paired photons generated in each process are cross polarized and guided by different guiding mechanisms, which produces entanglement in both polarization and spatial mode. Theoretical analysis shows that the output quantum state has a high quality of hyperentanglement by spectral filtering with a bandwidth of a few nanometers, while off-chip compensation is not needed. This technique offers a path to realize an electrically pumped hyperentangled photon source.Peer ReviewedPostprint (published version
Bragg reflection waveguide as a source of wavelength-multiplexed polarization-entangled photon pairs
We put forward a new highly efficient source of paired photons entangled in
polarization with an ultra-large bandwidth. The photons are generated by means
of a conveniently designed spontaneous parametric down-conversion process in a
semiconductor type-II Bragg reflection waveguide. The proposed scheme aims at
being a key element of an integrated source of polarization-entangled photon
pairs highly suitable for its use in a multi-user quantum-key-distribution
system
MIT ASTROMAG 1.7 meter disk magnet design report
MIT has proposed a magnet design for ASTROMAG, which has demonstrated substantial improvement in performance as compared with the present HEAO baseline design. Several advantages of the MIT disk design are listed along with design characteristics. Details of field contours and active field regions are shown along with comparisons with other designs. Three alternative design configurations for the ASTROMAG disk coils are summarized. The parameters of the conductors are listed and basic parameters for each of the complete systems are shown
Internal photoemission from plasmonic nanoparticles: comparison between surface and volume photoelectric effects
We study emission of photoelectrons from plasmonic nanoparticles into
surrounding matrix. We consider two mechanisms of the photoelectric effect from
nanoparticles - surface and volume ones, and use models of these two effects
which allow us to obtain analytical results for the photoelectron emission
rates from nanoparticle. Calculations have been done for the step potential at
surface of spherical nanoparticle, and the simple model for the hot electron
cooling have been used. We highlight the effect of the discontinuity of the
dielectric permittivity at the nanoparticle boundary in the surface mechanism,
which leads to substantial (by 5 times) increase of photoelectron emission rate
from nanoparticle compared to the case when such discontinuity is absent. For
plasmonic nanoparticle, a comparison of two mechanisms of the photoeffect was
done for the first time and showed that surface photoeffect, at least, does not
concede the volume one, which agrees with results for the flat metal surface
first formulated by Tamm and Schubin in their pioneering development of
quantum-mechanical theory of photoeffect in 1931. In accordance with our
calculations, this predominance of the surface effect is a result of effective
cooling of hot carriers, during their propagation from volume of the
nanoparticle to its surface in the scenario of the volume mechanism. Taking
into account both mechanisms is essential in development of devices based on
the photoelectric effect and in usage of hot electrons from plasmonic
nanoantenna.Comment: 13 pages, 10 figures, 61 reference
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