862 research outputs found
Algebraic and algorithmic frameworks for optimized quantum measurements
Von Neumann projections are the main operations by which information can be
extracted from the quantum to the classical realm. They are however static
processes that do not adapt to the states they measure. Advances in the field
of adaptive measurement have shown that this limitation can be overcome by
"wrapping" the von Neumann projectors in a higher-dimensional circuit which
exploits the interplay between measurement outcomes and measurement settings.
Unfortunately, the design of adaptive measurement has often been ad hoc and
setup-specific. We shall here develop a unified framework for designing
optimized measurements. Our approach is two-fold: The first is algebraic and
formulates the problem of measurement as a simple matrix diagonalization
problem. The second is algorithmic and models the optimal interaction between
measurement outcomes and measurement settings as a cascaded network of
conditional probabilities. Finally, we demonstrate that several figures of
merit, such as Bell factors, can be improved by optimized measurements. This
leads us to the promising observation that measurement detectors which---taken
individually---have a low quantum efficiency can be be arranged into circuits
where, collectively, the limitations of inefficiency are compensated for
A Radiative Model for the Weak Scale and Neutrino Mass via Dark Matter
We present a three-loop model of neutrino mass in which both the weak scale
and neutrino mass arise as radiative effects. In this approach, the scales for
electroweak symmetry breaking, dark matter, and the exotics responsible for
neutrino mass, are related due to an underlying scale-invariance. This
motivates the otherwise-independent O(TeV) exotic masses usually found in
three-loop models of neutrino mass. We demonstrate the existence of viable
parameter space and show that the model can be probed at colliders, precision
experiments, and dark matter direct-detection experiments.Comment: 24 pages, 7 figures; v2 Published versio
The Scale-Invariant Scotogenic Model
We investigate a minimal scale-invariant implementation of the scotogenic
model and show that viable electroweak symmetry breaking can occur while
simultaneously generating one-loop neutrino masses and the dark matter relic
abundance. The model predicts the existence of a singlet scalar (dilaton) that
plays the dual roles of triggering electroweak symmetry breaking and sourcing
lepton number violation. Important constraints are studied, including those
from lepton flavor violating effects and dark matter direct-detection
experiments. The latter turn out to be somewhat severe, already excluding large
regions of parameter space. None the less, viable regions of parameter space
are found, corresponding to dark matter masses below (roughly) 10 GeV and above
200 GeV.Comment: 21 pages, 8 figures; v2 JHEP versio
Assessments of macroscopicity for quantum optical states
With the slow but constant progress in the coherent control of quantum
systems, it is now possible to create large quantum superpositions. There has
therefore been an increased interest in quantifying any claims of
macroscopicity. We attempt here to motivate three criteria which we believe
should enter in the assessment of macroscopic quantumness: The number of
quantum fluctuation photons, the purity of the states, and the ease with which
the branches making up the state can be distinguished
A Model of Neutrino Mass and Dark Matter with an Accidental Symmetry
We present a model of radiative neutrino mass that automatically contains an
accidental symmetry and thus provides a stable dark matter candidate.
This allows a common framework for the origin of neutrino mass and dark matter
without invoking any symmetries beyond those of the Standard Model. The model
can be probed by direct-detection experiments and
searches, and predicts a charged scalar that can appear at the TeV scale,
within reach of collider experiments.Comment: 9 pages, 3 figures; v2 minor correction to PLB version (results
unchanged
Dependency-aware unequal erasure protection codes
Classical unequal erasure protection schemes split data to be protected into classes which are encoded independently. The unequal protection scheme presented in this paper is based on an erasure code which encodes all the data together according to the existing dependencies. A simple algorithm generates dynamically the generator matrix of the erasure code according to the packets streams structure, i.e., the dependencies between the packets, and the rate of the code. This proposed erasure code was applied to a packetized MPEG4 stream transmitted over a packet erasure channel and compared with other classical protection schemes in terms of PSNR and MOS. It is shown that the proposed code allows keeping a high video quality-level in a larger packet loss rate range than the other protection schemes
Generation of picosecond pulsed coherent state superpositions
We present the generation of approximated coherent state superpositions -
referred to as Schr\"odinger cat states - by the process of subtracting single
photons from picosecond pulsed squeezed states of light at 830 nm. The squeezed
vacuum states are produced by spontaneous parametric down-conversion (SPDC) in
a periodically poled KTiOPO4 crystal while the single photons are
probabilistically subtracted using a beamsplitter and a single photon detector.
The resulting states are fully characterized with time-resolved homodyne
quantum state tomography. Varying the pump power of the SPDC, we generated
different states which exhibit non-Gaussian behavior.Comment: 17 pages, 8 figures, 3 table
Bank Loan Agreement and CEO Compensation
Contrary to other forms of outside financing, the announcement of a bank loan agreement prompts a positive and significant market return. Throughout the literature, bank loans are deemed special and unique due to multiple benefits accruing to bank borrowers. The short-term positive market reaction is however inconsistent with the long-term underperformance of borrowing firms (Billet et al., 2006). We find that unlike shareholders, CEOs gain from the bank loan relation over the long-term. Specifically, we find that bank loan agreement elicits a significant increase in total compensation through an increase in non-performance based compensation components such as salary, bonus and other compensation. We also report a smaller proportion of performance based compensation following the bank agreement. Generally, the results suggest that subsequent to a major bank loan, CEOs seem to gain enough influence to shield their compensation from the firm \u27s underperformance. In particular this evidence supports the uniqueness of bank loan relations
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