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Search Results: 1 - 10 of 200616 matches for " P. Villoresi "
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Multiparameter entangled state engineering using adaptive optics
C. Bonato,D. Simon,P. Villoresi,A. V. Sergienko
Physics , 2008, DOI: 10.1103/PhysRevA.79.062304
Abstract: We investigate how quantum coincidence interferometry is affected by a controllable manipulation of transverse wave-vectors in type-II parametric down conversion using adaptive optics techniques. In particular, we discuss the possibility of spatial walk-off compensation in quantum interferometry and a new effect of even-order spatial aberration cancellation.
Aberration cancellation in quantum interferometry
C. Bonato,A. V. Sergienko,B. E. A. Saleh,S. Bonora,P. Villoresi
Physics , 2008, DOI: 10.1103/PhysRevLett.101.233603
Abstract: We report the first experimental demonstration of even-order aberration cancellation in quantum interferometry. The effect is a spatial counterpart of the spectral group velocity dispersion cancellation, which is associated with spectral entanglement. It is manifested in temporal interferometry by virtue of the multi-parameter spatial-spectral entanglement. Spatially-entangled photons, generated by spontaneous parametric down conversion, were subjected to spatial aberrations introduced by a deformable mirror that modulates the wavefront. We show that only odd-order spatial aberrations affect the quality of quantum interference.
Bi-photon propagation control with optimized wavefront by means of Adaptive Optics
M. Minozzi,S. Bonora,A. V. Sergienko,G. Vallone,P. Villoresi
Physics , 2012, DOI: 10.1364/OL.38.000489
Abstract: We present an efficient method to control the spatial modes of entangled photons produced through SPDC process. Bi-photon beam propagation is controlled by a deformable mirror, that shapes a 404nm CW diode laser pump interacting with a nonlinear BBO type-I crystal. Thanks to adaptive optical system, the propagation of 808nm SPDC light produced is optimized over a distance of 2m. The whole system optimization is carried out by a feedback between deformable mirror action and entangled photon coincidence counts. We also demonstrated the improvement of the two-photon coupling into single mode fibers.
Space-to-ground quantum-communication using an optical ground station: a feasibility study
P. Villoresi,F. Tamburini,M. Aspelmeyer,T. Jennewein,R. Ursin,C. Pernechele,G. Bianco,A. Zeilinger,C. Barbieri
Physics , 2004, DOI: 10.1117/12.564296
Abstract: We have tested the experimental prerequisites for a Space-to-Ground quantum communication link between satellites and an optical ground station. The feasibility of our ideas is being assessed using the facilities of the ASI Matera Laser Ranging Observatory (MLRO). Specific emphasis is put on the necessary technological modifications of the existing infrastructure to achieve single photon reception from an orbiting satellite.
Phase control of a longitudinal momentum entangled photon state by a deformable membrane mirror
Cristian Bonato,Stefano Bonora,Andrea Chiuri,Paolo Mataloni,Giorgio Milani,Giuseppe Vallone,Paolo Villoresi
Physics , 2009, DOI: 10.1364/JOSAB.27.00A175
Abstract: We propose a paradigmatic demonstration of the potentialities of a deformable mirror for closed-loop control of a two-photon momentum-entangled state, subject to phase fluctuations. A custom-made membrane mirror is used to set a relative phase shift between the arms of an interferometric apparatus. The control algorithm estimates the phase of the quantum state, by measurements of the coincidence events at the output ports of the interferometer, and uses the measurements results to provide a feedback signal to the deformable mirror. Stabilization of the coincidence rate to within 1.5 standard deviation of the Poissonian noise is demonstrated over 2000 seconds.
Feasibility of satellite quantum key distribution
Cristian Bonato,Andrea Tomaello,Vania Da Deppo,Giampiero Naletto,Paolo Villoresi
Physics , 2009, DOI: 10.1088/1367-2630/11/4/045017
Abstract: In this paper we present a novel analysis of the feasibility of quantum key distribution between a LEO satellite and a ground station. First of all, we study signal propagation through a turbulent atmosphere for uplinks and downlinks, discussing the contribution of beam spreading and beam wandering. Then we introduce a model for the background noise of the channel during night-time and day-time, calculating the signal-to-noise ratio for different configurations. We also discuss the expected error-rate due to imperfect polarization-compensation in the channel. Finally, we calculate the expected key generation rate of a secure key for different configurations (uplink, downlink) and for different protocols (BB84 with and without decoy states, entanglement-based Ekert91 protocol).
Frost risks in the Mantaro river basin
L. I. Dorman, N. G. Ptitsyna, G. Villoresi, V. V. Kasinsky, N. N. Lyakhov,M. I. Tyasto
Advances in Geosciences (ADGEO) , 2008,
Abstract: Eruptive activity of the Sun produces a chain of extreme geophysical events: high-speed solar wind, magnetic field disturbances in the interplanetary space and in the geomagnetic field and also intense fluxes of energetic particles. Space storms can potentially destroy spacecrafts, adversely affect astronauts and airline crew and human health on the Earth, lead to pipeline breaking, melt electricity transformers, and discontinue transmission. In this paper we deal with two consequences of space storms: (i) rise in failures in the operation of railway devices and (ii) rise in myocardial infarction and stroke incidences.
Space-QUEST: Experiments with quantum entanglement in space
Rupert Ursin,Thomas Jennewein,Johannes Kofler,Josep M. Perdigues,Luigi Cacciapuoti,Clovis J. de Matos,Markus Aspelmeyer,Alejandra Valencia,Thomas Scheidl,Alessandro Fedrizzi,Antonio Acin,Cesare Barbieri,Giuseppe Bianco,Caslav Brukner,Jose Capmany,Sergio Cova,Dirk Giggenbach,Walter Leeb,Robert H. Hadfield,Raymond Laflamme,Norbert Lutkenhaus,Gerard Milburn,Momtchil Peev,Timothy Ralph,John Rarity,Renato Renner,Etienne Samain,Nikolaos Solomos,Wolfgang Tittel,Juan P. Torres,Morio Toyoshima,Arturo Ortigosa-Blanch,Valerio Pruneri,Paolo Villoresi,Ian Walmsley,Gregor Weihs,Harald Weinfurter,Marek Zukowski,Anton Zeilinger
Physics , 2008, DOI: 10.1051/epn/2009503
Abstract: The European Space Agency (ESA) has supported a range of studies in the field of quantum physics and quantum information science in space for several years, and consequently we have submitted the mission proposal Space-QUEST (Quantum Entanglement for Space Experiments) to the European Life and Physical Sciences in Space Program. We propose to perform space-to-ground quantum communication tests from the International Space Station (ISS). We present the proposed experiments in space as well as the design of a space based quantum communication payload.
Experimental verification of the feasibility of a quantum channel between Space and Earth
Paolo Villoresi,Thomas Jennewein,Fabrizio Tamburini,Markus Aspelmeyer,Cristian Bonato,Rupert Ursin,Claudio Pernechele,Vincenza Luceri,Giuseppe Bianco,Anton Zeilinger,Cesare Barbieri
Physics , 2008, DOI: 10.1088/1367-2630/10/3/033038
Abstract: Extending quantum communication to Space environments would enable to perform fundamental experiments on quantum physics as well as applications of quantum information at planetary and interplanetary scales. Here, we report the first experimental implementation of a scheme for single-photon exchange between a satellite and an Earth-based station. We built an experiment that mimics a single photon source on a satellite, exploiting the telescope at the Matera Laser Ranging Observatory of the Italian Space Agency to detect the transmitted photons. Weak laser pulses, emitted by the ground-based station, are directed towards a satellite equipped with cube-corner retroreflectors. These reflect a small portion of the pulse, with an average of less-than-one photon per pulse directed to our receiver, as required for the faint-pulse quantum communication. We were able to detect returns from satellite Ajisai, a low-earth orbit geodetic satellite, whose orbit has a perigee height of 1485 km.
Prediction of galactic cosmic ray intensity variation for a few (up to 10-12) years ahead on the basis of convection-diffusion and drift model
L. I. Dorman, N. Iucci, A. V. Belov, A. E. Levitin, E. A. Eroshenko, N. G. Ptitsyna, G. Villoresi, G. V. Chizhenkov, L. I. Gromova, M. Parisi, M. I. Tyasto,V. G. Yanke
Annales Geophysicae (ANGEO) , 2005,
Abstract: A large database of anomalies, registered by 220 satellites in different orbits over the period 1971-1994 has been compiled. For the first time, data from 49 Russian Kosmos satellites have been included in a statistical analysis. The database also contains a large set of daily and hourly space weather parameters. A series of statistical analyses made it possible to quantify, for different satellite orbits, space weather conditions on the days characterized by anomaly occurrences. In particular, very intense fluxes (>1000 pfu at energy >10 MeV) of solar protons are linked to anomalies registered by satellites in high-altitude (>15000 km), near-polar (inclination >55°) orbits typical for navigation satellites, such as those used in the GPS network, NAVSTAR, etc. (the rate of anomalies increases by a factor ~20), and to a much smaller extent to anomalies in geostationary orbits, (they increase by a factor ~4). Direct and indirect connections between anomaly occurrence and geomagnetic perturbations are also discussed.
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