102,142 research outputs found
autogrill villoresi est: un modello per il terzo millennio
No full textDescrizione del progetto dell'Autogrill di Villoresi Est e delle sue qualità di sostenibilità ambientale ed inclusione : un benchmark per il settore della ristorazione autostradal
In-field comparison between G.652 and G.655 optical fibres for polarisation-based quantum key distribution
No full textIntegration of Quantum Key Distribution (QKD) in existing telecommunication infrastructure is crucial for the widespread adoption of this quantum technology that offers the distillation of unconditionally secure keys between users. The authors report a field trial between the Points of Presence placed in Treviso and in Venezia-Mestre, Italy, exploiting the QuKy commercial polarisation-based QKD platforms developed by ThinkQuantum S.r.l. and two different standards of single-mode optical fibres, that is, G.652 and G.655 as a quantum channel. In this field trial, several configurations were tested, including the co-existence of classical and quantum signals over the same fibre, providing a direct comparison between the performances of the G.652 and G.655 fibre standards for QKD applications.The authors compare the performance of a commercially available polarisation-based quantum key distribution (QKD) system in two parallel deployed fibres that employ two different standards, that is, G.652 and G.655, and in two different configurations, that is, dark-fibre and classical-quantum coexistence. This is a unique opportunity since the fibres are subject to the same environmental conditions, following the same route between the Points of Presence in Treviso and Venice-Mestre, Italy. imag
Effective non-vertical and apparent cutoff rigidities for a cosmic ray latitude survey from Antarctica to Italy in minimum of solar activity
No full textIn this paper we will report the results of the computation of cutoff rigidities of vertical and non-vertical incident cosmic ray particles.
Non-vertical effective cutoff rigidities have been computed by tracing particle trajectories through the ‘‘real’’ geomagnetic magnetic field
comprising the International Geomagnetic Reference Field model (IGRF95, IAGA Division 5 Working Group 8, 1996: Sabaka, T.J.,
Langel, R.A., Baldwin, R.T., Conrad, J.A. The geomagnetic field, 1900–1995, including the large scale fields from magnetospheric
sources and NASA candidate models for the 1995 IGRF revision. J. Geomag. Geoelect. 49, 157–206, 1997.) and the Tsyganenko [Tsyganenko,
N.A. A magnetospheric magnetic field model with a warped tail current sheet. Planet. Space Sci. 37, 5–20, 1989.] magnetosphere
model. The computation have been done for the backward route (from Antarctica to Italy) of the Italian Antarctic ship
survey 1996–1997, for geographic points corresponding to the daily average coordinates of the ship; for zenith angles 15°, 30°, 45°
and 60°, and azimuth angles from 0° to 360° in steps of 45°. By means of the obtained non-vertical cutoffs the apparent cutoff rigidities
have been calculated. The information on integral multiplicities of secondary neutrons detected by the neutron monitor in dependence of
the zenith angle of incoming primary cosmic ray particles have also been used. This information is based on the theoretical calculations
of meson-nuclear cascades of primary protons with different rigidities arriving to the Earth’s atmosphere at the zenith angles of 0°, 15°,
30°, 45°, 60° and 75°. The difference between the computed apparent and vertical cutoff rigidities reaches ~1 GV at rigidities >7–8 GV.
At rigidities of 10–16 GV, the difference between the apparent and vertical cutoff rigidities is larger than that obtained earlier by Clem
et al. [Clem, J.M., Bieber, J.W., Duldig, M., Evenson, P., Hall, D., Humble, J.E. Contribution of obliquely incident particles to neutron
monitor counting rate. J. Geophys. Res. 102, 26919–26926, 1997.] and Dorman et al. [Dorman, L.I., Villoresi, G., Iucci, N., Parisi, M.,
Tyasto, M.I., Danilova, O.A., Ptitsyna, N.G. Cosmic ray survey to Antarctica and coupling functions for neutron component near solar
minimum (1996–1997), 3. Geomagnetic effects and coupling functions. J. Geophys. Res. 105, 21047–21056, 2000.].
© 2007 COSPAR. Published by Elsevier Ltd. All rights reserved
Security bounds for decoy-state quantum key distribution with arbitrary photon-number statistics
No full textThe decoy-state method is a standard enhancement to quantum key distribution (QKD) protocols that has enabled countless QKD experiments with inexpensive light sources. However, new technological advancements might require further theoretical study of this technique. In particular, the decoy-state method is typically described under the assumption of a Poisson statistical distribution for the number of photons in each QKD pulse. This is a practical choice, because prepare-and-measure QKD is often implemented with attenuated lasers, which produce exactly this distribution. However, sources that do not meet this assumption are not guaranteed to be compatible with decoy states. In this work, we provide security bounds for decoy-state QKD using a source with an arbitrary photon emission statistic. We consider both the asymptotic limit of infinite key and the finite-size scenario, and evaluate two common decoy-state schemes: the vacuum+weak and one-decoy protocols. We numerically evaluate the performance of the bounds, comparing three realistic statistical distributions (Poisson, thermal, and binomial), showing that they are all viable options for QKD
Seedless ultrafast source-device independent quantum random number generator
No full textWe present a new source-device-independent protocol for quantum random number generation valid for arbitrary POVM. We experimentally implemented it using heterodyne detection reaching more than 17 Gbps of secure generation rate
Semi-Device-Independent Heterodyne-Based Quantum Random-Number Generator
No full textRandomness is a fundamental feature of quantum mechanics, which is an invaluable resource for both classical and quantum technologies. Practical quantum random-number generators (QRNGs) usually need to trust their devices, but their security can be jeopardized in the case of imperfections or malicious external actions. In this work, we present a robust implementation of a semi-device-independent QRNG that guarantees both security and fast generation rates. The system works in a prepare-and-measure scenario, where measurement and source are uncharacterized, but a bound on the energy of the prepared states is assumed. Our implementation exploits heterodyne detection, which offers increased generation rate and improved long-term stability compared to alternative measurement strategies. In particular, due to the tomographic properties of heterodyne measurement, we can compensate for fast phase fluctuations via postprocessing, avoiding complex active phase-stabilization systems. As a result, our scheme combines high security and speed with a simple setup featuring only commercial-off-the-shelf components, making it an attractive solution in many practical scenarios
Ultrabroadband pulse shaping with a push-pull deformable mirror
No full textWe report the programmable pulse shaping of ultrabroadband pulses by the use of a novel design of electrostatic deformable mirror based on push pull technology. We shape few-optical pulses from near-IR and visible optical parametric amplifiers, and demonstrate strong-field control of excited state population transfer in a dye molecule
CR-SA hysteresis phenomenon on the basis of alpha-particle satellite data
No full textWe analyzed satellite 5-min data on alpha-particle fluxes in energy intervals 60-160 MeV, 160-260 MeV and 330-500 MeV during January 1986 – May 2000. In the first we excluded periods with great CR increases caused by particle acceleration in solar flare events. Then we determined monthly averaged fluxes as well as 5 months and 11 months smooth averaged data. We corrected these data on drift effects according to the procedure described in Dorman (2004) in dependence of alpha-particle energies. Corrected on drifts alpha-particles fluxes we compare with expected according to convection-diffusion modulation for different values of supposed dimension of the modulation region (measured by time of solar wind propagation from the Sun to the boundary of this region Xo from 1 to 60 av. months; described in Dorman, 2004). By this way we can determine Xomax, at what the correlation coefficient reaches the maximum value. Then it can be determined the dimension of modulation region (with taking into account the influence of nonlinear processes on the solar wind speed in the outer Heliosphere according to Le Roux and Fichtner, 1997), the radial diffusion coefficient and transport path as well as expected alpha-particle intensity out of the modulation region and absolute alpha-particle modulation (relative to the alpha-particle intensity level in the interstellar space)
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