13,958 research outputs found
Entanglement and statistics in Hong-Ou-Mandel interferometry
Hong-Ou-Mandel interferometry allows one to detect the presence of
entanglement in two-photon input states. The same result holds for
two-particles input states which obey to Fermionic statistics. In the latter
case however anti-bouncing introduces qualitative differences in the
interferometer response. This effect is analyzed in a Gedankenexperiment where
the particles entering the interferometer are assumed to belong to a
one-parameter family of quons which continuously interpolate between the
Bosonic and Fermionic statistics.Comment: 7 pages, 3 figures; minor editorial changes and new references adde
Search for exchange-antisymmetric two-photon states
Atomic two-photon J=0 J'=1 transitions are forbidden for
photons of the same energy. This selection rule is related to the fact that
photons obey Bose-Einstein statistics. We have searched for small violations of
this selection rule by studying transitions in atomic Ba. We set a limit on the
probability that photons are in exchange-antisymmetric states:
.Comment: 5 pages, 4 figures, ReVTeX and .eps. Submitted to Phys. Rev. Lett.
Revised version 9/25/9
Anyons as quon particles
The momentum operator representation of nonrelativistic anyons is developed
in the Chern - Simons formulation of fractional statistics. The connection
between anyons and the q-deformed bosonic algebra is established.Comment: 10 pages,Late
Tides and the Evolution of Planetary Habitability
Tides raised on a planet by its host star's gravity can reduce a planet's
orbital semi-major axis and eccentricity. This effect is only relevant for
planets orbiting very close to their host stars. The habitable zones of
low-mass stars are also close-in and tides can alter the orbits of planets in
these locations. We calculate the tidal evolution of hypothetical terrestrial
planets around low-mass stars and show that tides can evolve planets past the
inner edge of the habitable zone, sometimes in less than 1 billion years. This
migration requires large eccentricities (>0.5) and low-mass stars (<0.35
M_Sun). Such migration may have important implications for the evolution of the
atmosphere, internal heating and the Gaia hypothesis. Similarly, a planet
detected interior to the habitable zone could have been habitable in the past.
We consider the past habitability of the recently-discovered, ~5 M_Earth
planet, Gliese 581 c. We find that it could have been habitable for reasonable
choices of orbital and physical properties as recently as 2 Gyr ago. However,
when we include constraints derived from the additional companions, we see that
most parameter choices that predict past habitability require the two inner
planets of the system to have crossed their mutual 3:1 mean motion resonance.
As this crossing would likely have resulted in resonance capture, which is not
observed, we conclude that Gl 581 c was probably never habitable.Comment: 31 pages, 10 figures, accepted to Astrobiology. A version with full
resolution figures is available at
http://www.lpl.arizona.edu/~rory/publications/brjg07.pd
Synchronized flow and wide moving jams from balanced vehicular traffic
Recently we proposed an extension to the traffic model of Aw, Rascle and
Greenberg. The extended traffic model can be written as a hyperbolic system of
balance laws and numerically reproduces the reverse shape of the
fundamental diagram of traffic flow. In the current work we analyze the steady
state solutions of the new model and their stability properties. In addition to
the equilibrium flow curve the trivial steady state solutions form two
additional branches in the flow-density diagram. We show that the
characteristic structure excludes parts of these branches resulting in the
reverse shape of the flow-density relation. The upper branch is
metastable against the formation of synchronized flow for intermediate
densities and unstable for high densities, whereas the lower branch is unstable
for intermediate densities and metastable for high densities. Moreover, the
model can reproduce the typical speed of the downstream front of wide moving
jams. It further reproduces a constant outflow from wide moving jams, which is
far below the maximum free flow. Applying the model to simulate traffic flow at
a bottleneck we observe a general pattern with wide moving jams traveling
through the bottleneck.Comment: 10 pages, 12 figure
Measurement of arbitrary scan patterns for correction of imaging distortions in laser scanning microscopy
: Laser scanning microscopy requires beam steering through relay and focusing optics at sub-micron precision. In light-weight mobile systems, such as head mounted multiphoton microscopes, distortion and imaging plane curvature management is unpractical due to the complexity of required optic compensation. Thus, the resulting scan pattern limits anatomical fidelity and decreases analysis algorithm efficiency. Here, we present a technique that reconstructs the three-dimensional scan path only requiring translation of a simple fluorescent test probe. Our method is applicable to any type of scanning instrument with sectioning capabilities without prior assumptions regarding origin of imaging deviations. Further, we demonstrate that the obtained scan pattern allows analysis of these errors, and allows to restore anatomical accuracy relevant for complementary methods such as motion correction, further enhancing spatial registration and feature extraction. <br
Adaptive application deployment of priority services in virtual environments
This paper introduces an adaptive application deployment service for virtualized environments (named DECIDE). This service facilitates the definition of customized cluster/cloud environment and the adaptive integration of scheduling policies for testing and deploying containerized applications. The service-based design of DECIDE and the use of a virtualized environment makes it possible to easily change the cluster/cloud configuration and its scheduling policy. It provides a differentiated service for application deployment based on priorities, according to user requirements. A prototype of this service was implemented using Apache MESOS and Docker. As a proof of concept, a federated application for electronic identification (eIDAS) was deployed using the DECIDE approach, which allows users to evaluate different deployment scenarios and scheduling policies providing useful information for decision making. Experiments were carried out to validate service functionality and the feasibility for testing and deploying applications that require different scheduling policies.This work was partially funded by the Spanish Ministry of Economy, Industry and Competitiveness under the grant TIN2016-79637-P âTowards Unification of HPC and Big Data Paradigmsâ
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