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Search Results: 1 - 10 of 401183 matches for " M. Gramegna "
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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.
A slow control system for the Garfield apparatus
M. Giacchini,F. Gramegna,S. Bertocco
Physics , 2001,
Abstract: The major part of the GARFIELD apparatus electronics are monitored and set up through a slow control system, which has been developed at LNL. A software package based on Lab View has been dedicated to the setting and control of 16 channels integrated Amplifiers and Constant Fraction Discriminators. GPIB controllers and GPIB-ENET interfaces have been used for the communication between the Personal Computer and the front-end of the electronics.
A first test of Wigner function local realistic model
G. Brida,M. Genovese,M. Gramegna,C. Novero,E. Predazzi
Physics , 2002, DOI: 10.1016/S0375-9601(02)00658-8
Abstract: We perform a first experimental test of a local realistic model, recently proposed, based on the Wigner function as probability distribution for the hidden variable. Our results disfavour the model and confirm standard quantum mechanics predictions.
Experimental limit on Spontaneous Parametric Up Conversion
G. Brida,M. Genovese,M. Gramegna,C. Novero
Physics , 2003, DOI: 10.1080/09500340308235521
Abstract: We present a first experimental test of the existence of Spontaneus Parametric Up Conversion, predicted by a specific local realistic model based on Wigner function formalism. The measurement has been made using a ccd camera on the emission of a LiIO3 crystal pumped by a 351 nm and/or a 789 (1064) nm lasers. We obtain an upper limit of 160 times on the ratio between intensity of Spontaneus Parametric Up Conversion and Spontaneous Parametric Down conversion.
A conclusive experiment to throw more light on "light"
G. Brida,M. Genovese,M. Gramegna,E. Predazzi
Physics , 2004, DOI: 10.1016/j.physleta.2004.06.050
Abstract: We describe a new realization of Ghose, Home, Agarwal experiment on wave particle duality of light where some limitations of the former experiment, realized by Mizobuchi and Ohtake, are overcome. Our results clearly indicate that wave-particle complementarity must be understood between interference and "whelcher weg" knowledge and not in a more general sense.
Review of recent experimental progresses in Foundations of Quantum Mechanics and Quantum Information obtained in Parametric Down Conversion Experiments at IENGF
M. Genovese,G. Brida,E. Cagliero,M. Gramegna,E. Predazzi
Physics , 2004, DOI: 10.1134/1.2034600
Abstract: We review some recent experimental progresses concerning Foundations of Quantum Mechanics and Quantum Information obtained in Quantum Optics Laboratory "Carlo Novero" at IENGF. More in details, after a short presentation of our polarization entangled photons source (based on precise superposition of two Type I PDC emission) and of the results obtained with it, we describe an innovative double slit experiment where two degenerate photons produced by PDC are sent each to a specific slit. Beyond representing an interesting example of relation between visibility of interference and "welcher weg" knowledge, this configuration has been suggested for testing de Broglie-Bohm theory against Standard Quantum Mechanics. Our results perfectly fit SQM results, but disagree with dBB predictions. Then, we discuss a recent experiment addressed to clarify the issue of which wave-particle observables are really to be considered when discussing wave particle duality. This experiments realises the Agarwal et al. theoretical proposal, overcoming limitations of a former experiment. Finally, we hint to the realization of a high-intensity high-spectral-selected PDC source to be used for quantum information studies.
Experimental realization of a measurement conditional unitary operation at single photon level and application to detector characterization
M. Genovese,G. Brida,M. Chekhova,M. Gramegna,L. Krivitsky,S. Kulik,M. L. Rastello
Physics , 2004, DOI: 10.1117/12.561416
Abstract: Our last experimental results on the realization of a measurement-conditional unitary operation at single photon level are presented. This gate operates by rotating by $90^o$ the polarization of a photon produced by means of Type-II Parametric Down Conversion conditional to a polarization measurement on the correlated photon. We then propose a new scheme for measuring the quantum efficiency of a single photon detection apparatus by using this set-up. We present experimental results obtained with this scheme compared with {\it traditional} biphoton calibration. Our results show the interesting potentiality of the suggested scheme.
Characterization of Spectral Entanglement of Spontaneous Parametric-Down Conversion Biphotons
G. Brida,V. Caricato,M. Genovese,M. Gramegna,M. V. Fedorov,S. P. Kulik
Physics , 2009, DOI: 10.1209/0295-5075/87/64003
Abstract: We verified operational approach based on direct measurement of entanglement degree for bipartite systems. In particular spectral distributions of single counts and coincidence for pure biphoton states generated by train of short pump pulses have been measured and entanglement quantifier calculated. The approach gives upper bound of entanglement stored in total biphoton states, which can reach extremely high value up to $10^{4}-10^{5}$.
Testing Ultrafast Two-Photon Spectral Amplitudes via Optical Fibres
G. Brida,V. Caricato,M. V. Chekhova,M. Genovese,M. Gramegna,T. Sh. Iskhakov
Physics , 2010, DOI: 10.1364/OE.18.012915
Abstract: We test two-dimensional TPSA of biphoton light emitted via ultrafast spontaneous parametric down-conversion (SPDC) using the effect of group-velocity dispersion in optical fibres. Further, we apply this technique to demonstrate the engineering of biphoton spectral properties by acting on the pump pulse shape.
On the reconstruction of diagonal elements of density matrix of quantum optical states by on/off detectors
G. Brida,M. Genovese,M. Gramegna,M. G. A. Paris,E. Predazzi,E. Cagliero
Physics , 2006,
Abstract: We discuss a scheme for reconstructing experimentally the diagonal elements of the density matrix of quantum optical states. Applications to PDC heralded photons, multi-thermal and attenuated coherent states are illustrated and discussed in some details.
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