189 research outputs found
Bell inequality violation by entangled single photon states generated from a laser, a LED or a Halogen lamp
In single-particle or intraparticle entanglement, two degrees of freedom of a
single particle, e.g., momentum and polarization of a single photon, are
entangled. Single-particle entanglement (SPE) provides a source of non
classical correlations which can be exploited both in quantum communication
protocols and in experimental tests of noncontextuality based on the
Kochen-Specker theorem. Furthermore, SPE is robust under decoherence phenomena.
Here, we show that single-particle entangled states of single photons can be
produced from attenuated sources of light, even classical ones. To
experimentally certify the entanglement, we perform a Bell test, observing a
violation of the Clauser, Horne, Shimony and Holt (CHSH) inequality. On the one
hand, we show that this entanglement can be achieved even in a classical light
beam, provided that first-order coherence is maintained between the degrees of
freedom involved in the entanglement. On the other hand, we prove that filtered
and attenuated light sources provide a flux of independent SPE photons that,
from a statistical point of view, are indistinguishable from those generated by
a single photon source. This has important consequences, since it demonstrates
that cheap, compact, and low power entangled photon sources can be used for a
range of quantum technology applications
Scalable Layer-2/Layer-3 Multistage Switching Architectures for Software Routers
Software routers are becoming an important alternative to proprietary and expensive network devices, because they exploit the economy of scale of the PC market and open-source software. When considering maximum performance in terms of throughput, PC-based routers suffer from limitations stemming from the single PC architecture, e.g., limited bus bandwidth, and high memory access latency. To overcome these limitations, in this paper we present a multistage architecture that combines a layer-2 load-balancer front-end and a layer-3 routing back-end, interconnected by standard Ethernet switches. Both the front-end and the back-end are implemented using standard PCs and open- source software. After describing the architecture, evaluation is performed on a lab test-bed, to show its scalability. While the proposed solution allows to increase performance of PC- based routers, it also allows to distribute packet manipulation functionalities, and to automatically recover from component failures
On the Observables Describing a Quantum Reference Frame
A reference frame F is described by the element g of the Poincare' group P
which connects F with a given fixed frame F_0. If F is a quantum frame, defined
by a physical object following the laws of quantum physics, the parameters of g
have to be considered as quantum observables. However, these observables are
not compatible and some of them, namely the coordinates of the origin of F,
cannot be represented by self-adjoint operators. Both these difficulties can be
overcome by considering a positive-operator-valued measure (POVM) on P,
covariant with respect to the left translations of the group, namely a
covariance system. We develop a construction procedure for this kind of
mathematical structure. The formalism is also used to discuss the quantum
observables measured with respect to a quantum reference frame.Comment: 23 pages, no figure
Energy Use Analysis for the Federal Energy Management Program
Recent congressional legislation allows federal agencies new authorities to
contract for energy savings by sharing the
acquired savings with an energy service
company. As part of its charter to make
the federal government more energy-efficient, the Federal Energy Management Program
(FEMP) endeavors to improve the technical basis for such performance-based
contracting. Specific tasks include the
development of improved energy use baselining methods, refinement of a simplified
energy analysis method and support to
users, preparation of guidelines and procedures
for energy savings initiatives,
and publication of a manual to guide identification and analysis of energy conservation measures. This paper describes the
current status and planned progress in
each of these areas, and how these relate
to several planned shared savings projects
A Rigorous Approach to the Feynman-Vernon Influence Functional and its Applications. I
A rigorous representation of the Feynman-Vernon influence functional used to describe open quantum systems is given, based on the theory of infinite dimensional oscillatory integrals. An application to the case of the density matrices describing the Caldeira-Leggett model of two quantum systems with a quadratic interaction is treated
Use of Metering for Facility and Whole Building Energy Analysis by the U.S. Depratment of Energy Federal Energy Management Program
This paper details how the U.S. Department of
Energy, Federal Energy Management Program (FEMP) is
applying metering technology to conduct empirically
based analyses o f energy use by federal agencies.
Continuing developments in sensors, data acquisition systems, microcomputers and monitoring protocols
are reducing the costs of metering to the point
that it is becoming "too cheap not to meter" energy
and the determinants of energy use at federal
facilities . This has widespread consequence for
FEMP if one accepts the axiom that "one can't manage
what one doesn't measure."
Several recently completed and ongoing
activities being managed by Pacific Northwest
laboratory for FEMP are highlighted in this
paper. This includes the metering of energy end uses
for a research laboratory building to support
a shared energy savings contract, analysis of
utility billing records, climate, and characteristics data for entire military bases to prioritize
energy use testing requirements, and enhancements
to simplified energy analysis tools to help federal
energy decision-makers identify and evaluate cost-effective energy savings opportunities
Approximation of Feynman path integrals with non-smooth potentials
We study the convergence in of the time slicing approximation of
Feynman path integrals under low regularity assumptions on the potential.
Inspired by the custom in Physics and Chemistry, the approximate propagators
considered here arise from a series expansion of the action. The results are
ultimately based on function spaces, tools and strategies which are typical of
Harmonic and Time-frequency analysis.Comment: 18 page
MUNICÍPIO RESILIENTE EM AFOGAMENTO
De acordo com a Organização Mundial da Saúde, afogamento é uma grave ameaça negligenciada à saúde pública, sendo que morrem em média 372.000 pessoas por ano em todo o mundo; 40 pessoas a cada hora do dia. No Brasil quase 1 milhão de pessoas se afogam e 5.700 morrem por afogamento a cada ano, sendo mais de 75% em rios, lagos e represas onde não existe nenhuma supervisão de guarda-vidas. Tendo em vista esta trágica realidade, é fundamental criar mecanismos de resiliência para estes locais, tendo como atores centrais os municípios, de forma a melhor efetivarem a gestão de riscos de afogamento em suas áreas geográficas
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