427 research outputs found

    The one-way CNOT simulation

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    In this paper we present the complete simulation of the quantum logic CNOT gate in the one-way model, that consists entirely of one-qubit measurements on a particular class of entangled states.Comment: 7 pages, 2 figure

    Theory of high-order harmonic generation from molecules by intense laser pulses

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    We show that high-order harmonics generated from molecules by intense laser pulses can be expressed as the product of a returning electron wave packet and the photo-recombination cross section (PRCS) where the electron wave packet can be obtained from simple strong-field approximation (SFA) or from a companion atomic target. Using these wave packets but replacing the PRCS obtained from SFA or from the atomic target by the accurate PRCS from molecules, the resulting HHG spectra are shown to agree well with the benchmark results from direct numerical solution of the time-dependent Schr\"odinger equation, for the case of H2+_2^+ in laser fields. The result illustrates that these powerful theoretical tools can be used for obtaining high-order harmonic spectra from molecules. More importantly, the results imply that the PRCS extracted from laser-induced HHG spectra can be used for time-resolved dynamic chemical imaging of transient molecules with temporal resolutions down to a few femtoseconds.Comment: 10 pages, 5 figure

    A Taylor series solution of the reactor point kinetics equations

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    The method of Taylor series expansion is used to develop a numerical solution to the reactor point kinetics equations. It is shown that taking a first order expansion of the neutron density and precursor concentrations at each time step gives results that are comparable to those obtained using other popular and more complicated methods. The algorithm developed using a Taylor series expansion is simple, completely transparent, and highly accurate. The procedure is tested using a variety of initial conditions and input data, including step reactivity, ramp reactivity, sinusoidal, and zigzag reactivity. These results are compared to those obtained using other methods.Comment: 13 pages, added 3 new figures, and 3 new reactivity conditions. Corrected data in table for sin reactivity cas

    A determination of the average up-down, strange and charm quark masses from Nf=2+1+1N_f=2+1+1

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    We present a lattice QCD determination of the average up-down, strange and charm quark masses based on simulations performed by the European Twisted Mass Collaboration with Nf=2+1+1N_f = 2 + 1 + 1 dynamical fermions. We simulated at three different values of the lattice spacing, the smallest being approximately 0.06fm0.06fm, and with pion masses as small as 210MeV210 \text{MeV}. Our results are: mud(2GeV)=3.70(17)MeVm_{ud}(2\text{GeV})=3.70(17)\text{MeV}, ms(2GeV)=99.2(3.9)MeVm_s(2\text{GeV})=99.2(3.9)\text{MeV}, mc(mc)=1.350(49)GeVm_c(m_c)=1.350(49)\text{GeV}, ms/mud=26.64(30)m_s/m_{ud}=26.64(30) and mc/ms=11.65(12)m_c/m_s=11.65(12)

    Multi-technique characterization of pictorial organic binders on XV century polychrome sculptures by combining microand non-invasive sampling approaches

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    A stony sculptural composition of the Nativity Scene is preserved in Altamura’s Cathedral (Apulia, Italy). This commonly called Apulian “presepe”, attributed to an unknown stonemason, is composed of polychrome carbonate white stone sculptures. While earlier stratigraphic tests have unveiled a complex superimposition of painting layers—meaning that several editions of the sculptures succeeded from the 16th to 20th century—a chemical investigation intended to identify the organic binding media used in painting layers was undertaken. Drawing on current literature, two strategies were exploited: a non-invasive in situ digestion analysis and an approach based on microremoval of painting film followed by the Bligh and Dyer extraction protocol. Both peptide and lipid mixtures were analyzed by matrix-assisted laser desorption/ionization-mass spectrometry (MALDIMS) and reversed-phase liquid chromatography coupled to mass spectrometry by electrospray ionization (RPLC-ESI-MS). Attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) examinations were also performed on micro-samples of painting films before lipids and proteins extraction. While human keratins were found to be common contaminants of the artwork’s surfaces, traces of animal collagen, siccative oils, and egg white proteins were evidenced in different sampling zones of the sculptures, thus suggesting the use of non-homogeneous painting techniques in the colored layers
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