8,152 research outputs found
General model of photon-pair detection with an image sensor
We develop an analytic model that relates intensity correlation measurements
performed by an image sensor to the properties of photon pairs illuminating it.
Experiments using both an effective single-photon counting (SPC) camera and a
linear electron-multiplying charge-coupled device (EMCCD) camera confirm the
model
Spin and spatial dynamics in electron-impact scattering off S-wave He using R-matrix with Time-Dependence theory
R-matrix with time-dependence theory is applied to electron-impact ionisation
processes for He in the S-wave model. Cross sections for electron-impact
excitation, ionisation and ionisation with excitation for impact energies
between 25 and 225 eV are in excellent agreement with benchmark cross sections.
Ultra-fast dynamics induced by a scattering event is observed through
time-dependent signatures associated with autoionisation from doubly excited
states. Further insight into dynamics can be obtained through examination of
the spin components of the time-dependent wavefunction.Comment: 6 pages, 5 figure
Adaptive Quantum Optics with Spatially Entangled Photon Pairs
Light shaping facilitates the preparation and detection of optical states and
underlies many applications in communications, computing, and imaging. In this
Letter, we generalize light shaping to the quantum domain. We show that
patterns of phase modulation for classical laser light can also shape higher
orders of spatial coherence, allowing deterministic tailoring of
high-dimensional quantum entanglement. By modulating spatially entangled photon
pairs, we create periodic, topological, and random patterns of quantum
illumination, without effect on intensity. We then structure the quantum
illumination to simultaneously compensate for entanglement that has been
randomized by a scattering medium and to characterize the medium's properties
via a quantum measurement of the optical memory effect. The results demonstrate
fundamental aspects of spatial coherence and open the field of adaptive quantum
optics
Light Propagation in inhomogeneous Universes
Using a multi-plane lensing method that we have developed, we follow the
evolution of light beams as they propagate through inhomogeneous universes. We
use a P3M code to simulate the formation and evolution of large-scale
structure. The resolution of the simulations is increased to sub-Megaparsec
scales by using a Monte Carlo method to locate galaxies inside the
computational volume according to the underlying particle distribution. The
galaxies are approximated by isothermal spheres, with each morphological type
having its own distribution of masses and core radii. The morphological types
are chosen in order to reproduce the observed morphology-density relation. This
algorithm has an effective resolution of 9 orders of magnitudes in length, from
the size of superclusters down to the core radii of the smallest galaxies.
We consider cold dark matter models normalized to COBE, and perform a large
parameter survey by varying the cosmological parameters Omega_0, lambda_0, H_0,
and n (the tilt of the primordial power spectrum). The values of n are chosen
by imposing particular values or sigma_8, the rms mass fluctuation at a scale
of 8/h Mpc. We use the power spectrum given by Bunn & White. This is the
largest parameter survey ever done is this field.Comment: 3 pages, gzip'ed tar file, including TeX source (not Latex). To be
published in a periodical of the Yukawa Institute for Theoretical Physics
(1998
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