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Search Results: 1 - 10 of 2514 matches for " Giorgio Brida "
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Tailoring polarization entanglement in anisotropy-compensated SPDC
Giorgio Brida,Marco Genovese,Maria V. Chekhova,Leonid A. Krivitsky
Physics , 2007, DOI: 10.1103/PhysRevA.77.015805
Abstract: We show that the angular spectrum of type-II SPDC contains a continuum of maximally entangled states. For the realization of a bright source of entangled two-photon states, a standard technique is to compensate for the transverse walk-off in the production crystal. We demonstrate that polarization entangled states can be effectively engineered by generalizing this approach. Our method allows to considerably enrich the set of generated entangled states with a controlled tailoring them.
Experimental Quantum Imaging exploiting multi-mode spatial correlation of twin beams
Giorgio Brida,Marco Genovese,Alice Meda,Ivano Ruo Berchera
Physics , 2010, DOI: 10.1103/PhysRevA.83.033811
Abstract: Properties of quantum states have disclosed new and revolutionary technologies, ranging from quantum information to quantum imaging. This last field is addressed to overcome limits of classical imaging by exploiting specific properties of quantum states of light. One of the most interesting proposed scheme exploits spatial quantum correlations between twin beams for realizing sub-shot-noise imaging of the weak absorbing objects, leading ideally to a noise-free imaging. Here we discuss in detail the experimental realization of this scheme, showing its capability to reach a larger signal to noise ratio with respect to classical imaging methods and, therefore, its interest for future practical applications.
Analysis of the possibility of analog detectors calibration by exploiting Stimulated Parametric Down Conversion
Giorgio Brida,Maria Chekhova,Marco Genovese,Ivano Ruo-Berchera
Physics , 2008, DOI: 10.1364/OE.16.012550
Abstract: Spontaneous parametric down conversion (SPDC) has been largely exploited as a tool for absolute calibration of photon-counting detectors, i.e detectors registering very small photon fluxes. In [J. Opt. Soc. Am. B 23, 2185 (2006)] we derived a method for absolute calibration of analog detectors using SPDC emission at higher photon fluxes, where the beam is seen as a continuum by the detector. Nevertheless intrinsic limitations appear when high-gain regime of SPDC is required to reach even larger photon fluxes. Here we show that stimulated parametric down conversion allow one to avoid this limitation, since stimulated photon fluxes are increased by the presence of the seed beam.
Quantum bit error rate in modeled atmospheres
Nicolo' Antonietti,Marina Mondin,Fred Daneshgaran,Giorgio Giovanelli,Ivan Kostadinov,Bruno Lunelli,Giorgio Brida,Marco Genovese,Marco Gramegna
Physics , 2008,
Abstract: The quantum bit error rate is a key quantity in quantum communications. If the quantum channel is the atmosphere, the information is usually encoded in the polarization of a photon. A link budget is required, which takes into account the depolarization of the photon after its interaction with the atmosphere as well as absorption, scattering and atmospheric emissions. An experimental setup for the reproduction of a simple model of the atmosphere is used to evaluate the quantum bit error rate in a BB84 protocol and the results are presented. This result represents a first step toward the realization of an optical bench experiment where atmospheric effects are simulated and controlled for reproducing the effects on a quantum channel in different meteorological situations.
Absolute Calibration of Analog Detectors by using Parametric Down Conversion
Giorgio Brida,Maria Chekhova,Marco Genovese,Alexander Penin,Maria Luisa Rastello,Ivano Ruo-Berchera
Physics , 2007,
Abstract: In this paper we report our systematic study of a promising absolute calibration technique of analog photo-detectors, based on the properties of parametric down conversion. Our formal results and a preliminary uncertainty analysis show that the proposed method can be effectively developed with interesting applications to metrology.
Detection of multimode spatial correlation in PDC and application to the absolute calibration of a CCD camera
Giorgio Brida,Ivo Pietro Degiovanni,Marco Genovese,Maria Luisa Rastello,Ivano Ruo-Berchera
Physics , 2010, DOI: 10.1364/OE.18.020572
Abstract: We propose and demonstrate experimentally a new method based on the spatial entanglement for the absolute calibration of analog detector. The idea consists on measuring the sub-shot-noise intensity correlation between two branches of parametric down conversion, containing many pairwise correlated spatial modes. We calibrate a scientific CCD camera and a preliminary evaluation of the statistical uncertainty indicates the metrological interest of the method.
Experimental tests of hidden variable theories from dBB to Stochastic Electrodynamics
Giorgio Brida,Marco Genovese,Marco Gramegna,Fabrizio Piacentini,Enrico Predazzi,Ivano Ruo-Berchera
Physics , 2006, DOI: 10.1088/1742-6596/67/1/012047
Abstract: In this paper we present some of our experimental results on testing hidden variable theories, which range from Bell inequalities measurements to a conclusive test of stochastic electrodynamics.
Measurement of sub-shot-noise spatial correlations without subtraction of background
Giorgio Brida,Lucia Caspani,Alessandra Gatti,Marco Genovese,Alice Meda,Ivano Ruo Berchera
Physics , 2008, DOI: 10.1103/PhysRevLett.102.213602
Abstract: In this paper we present the first measurement of sub-shot-noise spatial correlations without any subtraction of background, a result opening the way to realize sub-shot-noise imaging of weak objects
Absolute Quantum Efficiency Measurements by Means of Conditioned Polarization Rotation
Giorgio Brida,Maria Chekhova,Marco Genovese,Marco Gramegna,Leonid Krivitsky,Maria Luisa Rastello
Physics , 2005,
Abstract: We propose a new scheme for measuring the quantum efficiency of photon counting detectors by using correlated pho-tons. The measurement technique is based on a 90 rotation of the polarization of one photon member of a correlated pair produced by parametric down-conversion, conditioned on the detection of the other correlated photon after polarization selection. We present experimental results obtained with this scheme.
Experimental quantum cryptography scheme based on orthogonal states
Alessio Avella,Giorgio Brida,Ivo Pietro Degiovanni,Marco Genovese,Marco Gramegna,Paolo Traina
Physics , 2010, DOI: 10.1103/PhysRevA.82.062309
Abstract: Since, in general, non-orthogonal states cannot be cloned, any eavesdropping attempt in a Quantum Communication scheme using non-orthogonal states as carriers of information introduces some errors in the transmission, leading to the possibility of detecting the spy. Usually, orthogonal states are not used in Quantum Cryptography schemes since they can be faithfully cloned without altering the transmitted data. Nevertheless, L. Goldberg and L. Vaidman [\prl 75 (1995) 1239] proposed a protocol in which, even if the data exchange is realized using two orthogonal states, any attempt to eavesdrop is detectable by the legal users. In this scheme the orthogonal states are superpositions of two localized wave packets travelling along separate channels. Here we present an experiment realizing this scheme.
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