7,468 research outputs found
Measurements of entanglement over a kilometric distance to test superluminal models of Quantum Mechanics: preliminary results
As shown in the \emph{EPR} paper (Einstein, Podolsky e Rosen, 1935), Quantum
Mechanics is a non-local Theory. The Bell theorem and the successive
experiments ruled out the possibility of explaining quantum correlations using
only local hidden variables models. Some authors suggested that quantum
correlations could be due to superluminal communications that propagate
isotropically with velocity \emph{} in a preferred reference frame.
For finite values of \emph{} and in some special cases, Quantum
Mechanics and superluminal models lead to different predictions. So far, no
deviations from the predictions of Quantum Mechanics have been detected and
only lower bounds for the superluminal velocities \emph{} have been
established. Here we describe a new experiment that increases the maximum
detectable superluminal velocities and we give some preliminary results.Comment: 16 pages, 10 figures, Eighth International Workshop DICE2016,
Castiglioncello (IT), September 12-16, 201
Spaceborne CO2 laser communications systems
Projections of the growth of earth-sensing systems for the latter half of the 1980's show a data transmission requirement of 300 Mbps and above. Mission constraints and objectives lead to the conclusion that the most efficient technique to return the data from the sensing satellite to a ground station is through a geosynchronous data relay satellite. Of the two links that are involved (sensing satellite to relay satellite and relay satellite to ground), a laser system is most attractive for the space-to-space link. The development of CO2 laser systems for space-to-space applications is discussed with the completion of a 300 Mpbs data relay receiver and its modification into a transceiver. The technology and state-of-the-art of such systems are described in detail
Experimental quantum teleportation over a high-loss free-space channel
We present a high-fidelity quantum teleportation experiment over a high-loss
free-space channel between two laboratories. We teleported six states of three
mutually unbiased bases and obtained an average state fidelity of 0.82(1), well
beyond the classical limit of 2/3. With the obtained data, we tomographically
reconstructed the process matrices of quantum teleportation. The free-space
channel attenuation of 31 dB corresponds to the estimated attenuation regime
for a down-link from a low-earth-orbit satellite to a ground station. We also
discussed various important technical issues for future experiments, including
the dark counts of single-photon detectors, coincidence-window width etc. Our
experiment tested the limit of performing quantum teleportation with
state-of-the-art resources. It is an important step towards future
satellite-based quantum teleportation and paves the way for establishing a
worldwide quantum communication network
Determination of optical technology experiments for a satellite
Optical technology experiments for satellite - communications, acquisition, tracking, lasers, photometry, and atmospheric
Long-Distance Quantum Communication with Entangled Photons using Satellites
The use of satellites to distribute entangled photon pairs (and single
photons) provides a unique solution for long-distance quantum communication
networks. This overcomes the principle limitations of Earth-bound technology,
i.e. the narrow range of some 100 km provided by optical fiber and terrestrial
free-space links.Comment: 12 pages, 7 figures; submitted to IEEE Journal of Selected Topics in
Quantum Electronics, special issue on "Quantum Internet Technologies
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