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Search Results: 1 - 10 of 189885 matches for " G. Brida "
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Crecimiento económico y trampas de pobreza: cuál es el papel del capital humano?
Elvio Accinelli,Juan G. Brida,Silvia London
Investigación económica , 2007,
Experimental realization of sub-shot-noise quantum imaging
G. Brida,M. Genovese,I. Ruo Berchera
Physics , 2010, DOI: 10.1038/NPHOTON.2010.29
Abstract: Properties of quantum states have disclosed new technologies, ranging from quantum information to quantum metrology. Among them a recent research field is quantum imaging, addressed to overcome limits of classical imaging by exploiting spatial properties of quantum states of light . In particular quantum correlations between twin beams represent a fundamental resource for these studies. One of the most interesting proposed scheme exploits spatial quantum correlations between parametric down conversion light beams for realizing sub-shot-noise imaging of the weak absorbing objects, leading ideally to a noise-free imaging. Here we present the first experimental realisation of this scheme, showing its capability to reach a larger signal to noise ratio (SNR) with respect to classical imaging methods. This work represents the starting point of this quantum technology that can have relevant applications, especially whenever there is a need of a low photon flux illumination (e.g. as with certain biological samples).
Experimental local realism tests without fair sampling assumption
G. Brida,M. Genovese,F. Piacentini
Physics , 2007, DOI: 10.1140/epjd/e2007-00194-5
Abstract: Following the theoretical suggestion of Ref. [1,2], we present experimental results addressed to test restricted families of local realistic models, but without relying on the fair sampling assumption.
Twin-photon techniques for photo-detector calibration
G. Brida,M. Genovese,M. Gramegna
Physics , 2005, DOI: 10.1002/lapl.200510077
Abstract: The aim of this review paper is to enlighten some recent progresses in quantum optical metrology in the part of quantum efficiency measurements of photo-detectors performed with bi-photon states. The intrinsic correlated nature of entangled photons from Spontaneous Parametric Down Conversion phenomenon has opened wide horizons to a new approach for the absolute measurement of photo-detector quantum efficiency, outgoing the requirement for conventional standards of optical radiation; in particular the simultaneous feature of the creation of conjugated photons led to a well known technique of coincidence measurement, deeply understood and implemented for standard uses. On the other hand, based on manipulation of entanglement developed for Quantum Information protocols implementations, a new method has been proposed for quantum efficiency measurement, exploiting polarisation entanglement in addition to energy-momentum and time ones, that is based on conditioned polarisation state manipulation. In this review, after a general discussion on absolute photo-detector calibration, we compare these different methods, in order to give an accurate operational sketch of the absolute quantum efficiency measurement state of the art.
On The Measurement of Photon Flux in Parametric Down Conversion
G. Brida,M. Genovese,C. Novero
Physics , 1999, DOI: 10.1007/s100530050036
Abstract: We report the measurement of the photons flux produced in parametric down-conversion, performed in photon counting regime with actively quenched silicon avalanche photodiodes as single photon detectors. Measurements are done with the detector in a well defined geometrical and spectral situation. By comparison of the experimental data with the theory, a value for the second order susceptibilities of the non linear crystal can be inferred.
An application of two photon entangled states to quantum metrology
G. Brida,M. Genovese,C. Novero
Physics , 1999, DOI: 10.1080/09500340008235132
Abstract: Besides many interesting application to the study of foundations of quantum mechanics, entangled state are now assuming a large relevance for some practical application. In particular, we discuss most recent results obtained in our laboratory on the use of two photons entangled states produced in parametric down conversion for absolute quantum efficiency calibration of photodetectors, in photon counting regime.
Systematic Numerical Study of the Propagation of Monochromatic Radiation through a Stationary Atmosphere in a Model of Plane Plane-Parallel Layers
N. Antonietti,M. Mondin,G. Catastini,G. Brida,M. Genovese
Physics , 2007, DOI: 10.1134/S1054660X07120092
Abstract: In this paper, the authors compare the security bounds for different quantum communication protocols with the numerically evaluated losses in the transmission channel, due to the interaction between the atmosphere and the photon, which is the information carrier. The analysis is carried out using a free-source library, which can solve the radiative transfer equation for a parallel-plane atmosphere.
Joint multipartite photon statistics by on/off detection
G. Brida,M. Genovese,M. G. A. Paris,F. Piacentini
Physics , 2006, DOI: 10.1364/OL.31.003508
Abstract: We demonstrate a method to reconstruct the joint photon statistics of two or more modes of radiation using on/off photodetection performed at different quantum efficiencies. The two-mode case is discussed in details and experimental results are presented for the bipartite states obtained after a beam-splitter fed by a single photon state or a thermal state.
Ultrafast Non-Thermal Electron Dynamics in Single Layer Graphene
Brida D.,Manzoni C.,Cerullo G.,Tomadin A.
EPJ Web of Conferences , 2013, DOI: 10.1051/epjconf/20134104025
Abstract: We study the ultrafast dynamics of non-thermal electron relaxation in graphene upon impulsive excitation. The 10-fs resolution two color pump-probe allows us to unveil the non-equilibrium electron gas decay at early times.
Fully coherent spectral broadening of femtosecond pulses from an Er:fiber system
Kumkar S.,Krauss G.,Brida D.,Leitenstorfer A.
EPJ Web of Conferences , 2013, DOI: 10.1051/epjconf/20134110015
Abstract: Coherence properties of the ultrabroadband output from a highly nonlinear germanosilicate fiber pumped by a femtosecond Er:fiber source are investigated. Conditions necessary to achieve full spectral coherence are demonstrated experimentally and analyzed theoretically.
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