4,511 research outputs found
Fully quantum mechanical dynamic analysis of single-photon transport in a single-mode waveguide coupled to a traveling-wave resonator
We analyze the dynamics of single photon transport in a single-mode waveguide
coupled to a micro-optical resonator using a fully quantum mechanical model. We
examine the propagation of a single-photon Gaussian packet through the system
under various coupling conditions. We review the theory of single photon
transport phenomena as applied to the system and we develop a discussion on the
numerical technique we used to solve for dynamical behavior of the quantized
field. To demonstrate our method and to establish robust single photon results,
we study the process of adiabatically lowering or raising the energy of a
single photon trapped in an optical resonator under active tuning of the
resonator. We show that our fully quantum mechanical approach reproduces the
semi-classical result in the appropriate limit and that the adiabatic invariant
has the same form in each case. Finally, we explore the trapping of a single
photon in a system of dynamically tuned, coupled optical cavities.Comment: 24 pages, 10 figure
Binary Induced Neutron-Star Compression, Heating, and Collapse
We analyze several aspects of the recently noted neutron star collapse
instability in close binary systems. We utilize (3+1) dimensional and spherical
numerical general relativistic hydrodynamics to study the origin, evolution,
and parametric sensitivity of this instability. We derive the modified
conditions of hydrostatic equilibrium for the stars in the curved space of
quasi-static orbits. We examine the sensitivity of the instability to the
neutron star mass and equation of state. We also estimate limits to the
possible interior heating and associated neutrino luminosity which could be
generated as the stars gradually compress prior to collapse. We show that the
radiative loss in neutrinos from this heating could exceed the power radiated
in gravity waves for several hours prior to collapse. The possibility that the
radiation neutrinos could produce gamma-ray (or other electromagnetic) burst
phenomena is also discussed.Comment: 17 pages, 7 figure
Revised Relativistic Hydrodynamical Model for Neutron-Star Binaries
We report on numerical results from a revised hydrodynamic simulation of
binary neutron-star orbits near merger. We find that the correction recently
identified by Flanagan significantly reduces but does not eliminate the
neutron-star compression effect. Although results of the revised simulations
show that the compression is reduced for a given total orbital angular
momentum, the inner most stable circular orbit moves to closer separation
distances. At these closer orbits significant compression and even collapse is
still possible prior to merger for a sufficiently soft EOS. The reduced
compression in the corrected simulation is consistent with other recent studies
of rigid irrotational binaries in quasiequilibrium in which the compression
effect is observed to be small. Another significant effect of this correction
is that the derived binary orbital frequencies are now in closer agreement with
post-Newtonian expectations.Comment: Submitted to Phys. Rev.
Global Properties of the 4-He + 28-Si Reaction at 117.4 and 198.5 MeV
This research was sponsored by the National Science Foundation Grant NSF PHY 87-1440
Optoelectronic Reservoir Computing
Reservoir computing is a recently introduced, highly efficient bio-inspired
approach for processing time dependent data. The basic scheme of reservoir
computing consists of a non linear recurrent dynamical system coupled to a
single input layer and a single output layer. Within these constraints many
implementations are possible. Here we report an opto-electronic implementation
of reservoir computing based on a recently proposed architecture consisting of
a single non linear node and a delay line. Our implementation is sufficiently
fast for real time information processing. We illustrate its performance on
tasks of practical importance such as nonlinear channel equalization and speech
recognition, and obtain results comparable to state of the art digital
implementations.Comment: Contains main paper and two Supplementary Material
A. Lincoln: Late President of the United States
The engraving features a black and white portrait image of Abraham Lincoln from the chest up. He is dressed in a suit and tie.https://scholarsjunction.msstate.edu/fvw-prints/1197/thumbnail.jp
Finite temperature effects on cosmological baryon diffusion and inhomogeneous Big-Bang nucleosynthesis
We have studied finite temperature corrections to the baryon transport cross
sections and diffusion coefficients. These corrections are based upon the
recently computed renormalized electron mass and the modified state density due
to the background thermal bath in the early universe. It is found that the
optimum nucleosynthesis yields computed using our diffusion coefficients shift
to longer distance scales by a factor of about 3. We also find that the minimum
value of abundance decreases by while and
increase. Effects of these results on constraints from primordial
nucleosynthesis are discussed. In particular, we find that a large baryonic
contribution to the closure density (\Omega_b h_{50}^{2} \lsim 0.4) may be
allowed in inhomogeneous models corrected for finite temperature.Comment: 7 pages, 6 figures, submitted to Phys. Rev.
- âŠ