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D'Arrigo A.,Centro Siciliano Of Fisica Nucleare E Struttura Della Materia Csfnsm | D'Arrigo A.,University of Catania | D'Arrigo A.,CNR Institute for Microelectronics and Microsystems | Falci G.,University of Catania | And 5 more authors.
International Journal of Quantum Information | Year: 2014

Controlling the dynamics of entanglement and preventing its disappearance are central requisites for any implementation of quantum information processing. Solid state qubits are frequently affected by random telegraph noise due to bistable impurities of different nature coupled to the device. In this paper, we investigate the possibility to achieve an efficient universal two-qubit gate in the presence of random telegraph noise by periodic dynamical decoupling. We find an analytic form of the gate error as a function of the number of applied pulses valid when the gate time is much shorter then the telegraphic process correlation time. The analysis is further supplemented by exact numerical results demonstrating the feasibility of a highly-efficient universal two-qubit gate. © 2014 World Scientific Publishing Company. Source

Lamia L.,University of Catania | Spitaleri C.,University of Catania | Spitaleri C.,National Institute of Nuclear Physics, Italy | La Cognata M.,National Institute of Nuclear Physics, Italy | And 3 more authors.
Astronomy and Astrophysics | Year: 2012

Context. The charged-particle induced reactions on lithium have been studied by several works. In particular, several direct measurements of the 7Li(p, α) 4He reaction have been performed to extrapolate its low-energy astrophysical S(E)-factor and evaluate the electron screening potential, U e. Aims. In view of recent direct measurements, we discuss our estimate of the bare-nucleus S(E)-factor and an evaluation of the corresponding reaction rate. Moreover, we present the extracted electron screening potential. Methods. The Trojan Horse method (THM) allows us to measure the 7Li(p, α) 4He bare-nucleus S(E)-factor down to energies of ~10 keV, rendering unnecessary the extrapolation procedure typically used by the direct measurements. The 7Li(p, α) 4He S(E)-factor is deduced from the 2H( 7Li, α 4He)n reaction by selecting the quasi-free contribution to the reaction yield. The plane-wave impulse approximation has proved an effective approach as distortions appear negligible. Results. The THM enable us to measure the 7Li(p, α) 4He S(E)-factor over the energy region of interest for astrophysics, namely 0.01 < E cm < 0.4 MeV. The zero-energy S(E)-factor and the U e electron screening potential have been measured and compared with the available direct data. From the TH measure of the 7Li(p, α) 4He S(E)-factor, the reaction rate calculation has been performed in correspondence with the temperature window of 0.01 < T 9 < 2, which is typical of several astrophysical sites where Li burning could shed light on some open questions, such as mixing phenomena. A variation of ~13%, with respect the adopted NACRE one, has been found at temperatures of about T 9 = 10 -3, while a variation of ~5% has been found at higher temperatures. By considering in the calculation the upper and lower limits to the TH reaction rate, no significant variation in the Li abundances of low mass giant stars follows or, if any modification occurs, this is negligible in comparison to the uncertainties in the free parameters considered in the extra-mixing model of Palmerini and collaborators. © 2012 ESO. Source

Adriani O.,University of Florence | Adriani O.,National Institute of Nuclear Physics, Italy | Barbarino G.C.,University of Naples Federico II | Barbarino G.C.,National Institute of Nuclear Physics, Italy | And 75 more authors.
Astrophysical Journal | Year: 2014

The propagation of cosmic rays inside our galaxy plays a fundamental role in shaping their injection spectra into those observed at Earth. One of the best tools to investigate this issue is the ratio of fluxes for secondary and primary species. The boron-to-carbon (B/C) ratio, in particular, is a sensitive probe to investigate propagation mechanisms. This paper presents new measurements of the absolute fluxes of boron and carbon nuclei as well as the B/C ratio from the PAMELA space experiment. The results span the range 0.44-129 GeV/n in kinetic energy for data taken in the period 2006 July to 2008 March. © 2014. The American Astronomical Society. All rights reserved. Source

Adriani O.,University of Florence | Adriani O.,National Institute of Nuclear Physics, Italy | Barbarino G.C.,University of Naples Federico II | Barbarino G.C.,National Institute of Nuclear Physics, Italy | And 68 more authors.
Physical Review Letters | Year: 2015

In this work we present results of a direct search for strange quark matter (SQM) in cosmic rays with the PAMELA space spectrometer. If this state of matter exists it may be present in cosmic rays as particles, called strangelets, having a high density and an anomalously high mass-to-charge (A/Z) ratio. A direct search in space is complementary to those from ground-based spectrometers. Furthermore, it has the advantage of being potentially capable of directly identifying these particles, without any assumption on their interaction model with Earth's atmosphere and the long-term stability in terrestrial and lunar rocks. In the rigidity range from 1.0 to ∼1.0×103GV, no such particles were found in the data collected by PAMELA between 2006 and 2009. An upper limit on the strangelet flux in cosmic rays was therefore set for particles with charge 1≤Z≤8 and mass 4≤A≤1.2×105. This limit as a function of mass and as a function of magnetic rigidity allows us to constrain models of SQM production and propagation in the Galaxy. © 2015 American Physical Society. Source

Malakhov V.V.,National Research Nuclear University MEPhI | Koldashov S.V.,National Research Nuclear University MEPhI | Mayorov A.G.,National Research Nuclear University MEPhI | Mayorova M.A.,National Research Nuclear University MEPhI | And 70 more authors.
Journal of Physics: Conference Series | Year: 2015

The PAMELA and the ARINA experiments are carried out on the board of satellite RESURS-DK1 since 2006 up to now. Main goal of the PAMELA instrument is measurements of high energy antiparticles in cosmic rays while the ARINA instrument is intended studying high energy charged particle bursts in the magnetosphere. Both of these experiments have a possibility to study trapped particles in the inner radiation belt. Complex of these two instruments covers proton energy range from 30 MeV up to trapping limit (E= ∼2 GeV). Continuous measurements with the PAMELA and the ARINA spectrometers include falling and rising phases of 23/24 solar cycles and maximum of 24th one. In this report we present temporal profiles of proton flux in the inner zone of the radiation belt (1.11 < L < 1.18, 0.18 < B < 0.22G). Dependence of proton fluxes on a magnitude of the solar activity was studied for various phases of 23/24 solar cycles. At that it was shown that proton fluxes at the solar minimum are several times greater than at the solar maximum. © Published under licence by IOP Publishing Ltd. Source

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