2,226 research outputs found
Quantum Optics in Maxwell's Fish Eye Lens with Single Atoms and Photons
We investigate the quantum optical properties of Maxwell's two-dimensional
fish eye lens at the single-photon and single-atom level. We show that such a
system mediates effectively infinite-range dipole-dipole interactions between
atomic qubits, which can be used to entangle multiple pairs of distant qubits.
We find that the rate of the photon exchange between two atoms, which are
detuned from the cavity resonances, is well described by a model, where the
photon is focused to a diffraction-limited area during absorption. We consider
the effect of losses on the system and study the fidelity of the entangling
operation via dipole-dipole interaction. We derive our results analytically
using perturbation theory and the Born-Markov approximation and then confirm
their validity by numerical simulations. We also discuss how the
two-dimensional Maxwell's fish eye lens could be realized experimentally using
transformational plasmon optics.Comment: 20 pages, 7 figure
Quantum walks based on an interferometric analogy
There are presently two models for quantum walks on graphs. The "coined" walk
uses discrete time steps, and contains, besides the particle making the walk, a
second quantum system, the coin, that determines the direction in which the
particle will move. The continuous walk operates with continuous time. Here a
third model for a quantum walk is proposed, which is based on an analogy to
optical interferometers. It is a discrete-time model, and the unitary operator
that advances the walk one step depends only on the local structure of the
graph on which the walk is taking place. No quantum coin is introduced. This
type of walk allows us to introduce elements, such as phase shifters, that have
no counterpart in classical random walks. Walks on the line and cycle are
discussed in some detail, and a probability current for these walks is
introduced. The relation to the coined quantum walk is also discussed. The
paper concludes by showing how to define these walks for a general graph.Comment: Latex,18 pages, 5 figure
X-ray, UV and optical analysis of supergiants: Ori
We present a multi-wavelength (X-ray to optical) analysis, based on non-local
thermodynamic equilibrium photospheric+wind models, of the B0 Ia-supergiant:
~Ori. The aim is to test the consistency of physical parameters, such
as the mass-loss rate and CNO abundances, derived from different spectral
bands. The derived mass-loss rate is
1.610 M yr where
is the volume filling factor. However, the S IV
1062,1073 profiles are too strong in the models; to fit the
observed profiles it is necessary to use 0.01. This value is a
factor of 5 to 10 lower than inferred from other diagnostics, and implies
M yr. The discrepancy could
be related to porosity-vorosity effects or a problem with the ionization of
sulfur in the wind. To fit the UV profiles of N V and O VI it was necessary to
include emission from an interclump medium with a density contrast
() of 100. X-ray emission in H-He like and Fe L
lines was modeled using four plasma components located within the wind. We
derive plasma temperatures from to K, with
lower temperatures starting in the outer regions (R3-6 R), and a
hot component starting closer to the star (R2.9 R). From X-ray
line profiles we infer M yr. The
X-ray spectrum (0.1 kev) yields an X-ray luminosity , consistent with the superion line profiles.
X-ray abundances are in agreement with those derived from the UV and optical
analysis: Ori is slightly enhanced in nitrogen and depleted in
carbon and oxygen, evidence for CNO processed material.Comment: 33 pages, 25 figures. Accepted for publication in MNRA
MathOptimizer: a nonlinear optimization package for mathematica users
Özyeğin University Technical ReportMathematica is an advanced software system that enables symbolic computing, numerics, program code development, model visualization and professional documentation in a unified framework. Our MathOptimizer software package serves to solve global and local optimization models developed using Mathematica. We introduce MathOptimizer’s key features and discuss its usage options that support a range of operational modes. The numerical capabilities of the package are illustrated by simple and more advanced examples, pointing towards a broad range of potential applications
Vesicular-arbuscular mycorrhizae in two tropical monodominant trees
Journal ArticleMycorrhizae, symbioses between plant roots and fungi, are in virtually all terrestrial plant ecosystems. Substantial evidence indicates that mycorrhizal associations are beneficial to both partners. In most systems, the fungus benefits the host plant by effectively scavenging nutrients and in return, utilizes carbohydrates produced by the plant (Allen 1991, Harley & Smith 1983)
Topological Quantum Optics in Two-Dimensional Atomic Arrays
We demonstrate that two-dimensional atomic emitter arrays with subwavelength
spacing constitute topologically protected quantum optical systems where the
photon propagation is robust against large imperfections while losses
associated with free space emission are strongly suppressed. Breaking
time-reversal symmetry with a magnetic field results in gapped photonic bands
with non-trivial Chern numbers and topologically protected, long-lived edge
states. Due to the inherent nonlinearity of constituent emitters, such systems
provide a platform for exploring quantum optical analogues of interacting
topological systems.Comment: 11 pages and 9 figures; paper updated to match published versio
The interplay between the level of voluntary participation and supervisor support on trainee motivation and transfer
International audienceAbstract There have been conflicting findings about whether mandatory versus voluntary training leads to more positive training outcomes. We propose moving away from a dichotomous distinction to a more dynamic participation approach to better elucidate theoretical differences relating to self‐determination theory. A sample of 311 trainees from eight companies participated in a variety of open skill (e.g., leadership) training programs. Results indicated that higher levels of voluntary participation were positively related to trainees' transfer motivation and training transfer. We also found that the level of voluntary participation moderates the relationship between supervisor support and both motivation to transfer and training transfer. Supervisor support facilitates trainee motivation and transfer to a larger extent when participation is less voluntary. Future training should be framed and promoted to increase employee motivation to voluntarily participate, especially for employees with less supervisor support
A method to suppress dielectric breakdowns in liquid argon ionization detectors for cathode to ground distances of several millimeters
We present a method to reach electric field intensity as high as 400 kV/cm in
liquid argon for cathode-ground distances of several millimeters. This can be
achieved by suppressing field emission from the cathode, overcoming limitations
that we reported earlier
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