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961.
Sansoni L Sciarrino F Vallone G Mataloni P Crespi A Ramponi R Osellame R 《Physical review letters》2012,108(1):010502
Quantum walk represents one of the most promising resources for the simulation of physical quantum systems, and has also emerged as an alternative to the standard circuit model for quantum computing. Here we investigate how the particle statistics, either bosonic or fermionic, influences a two-particle discrete quantum walk. Such an experiment has been realized by exploiting polarization entanglement to simulate the bunching-antibunching feature of noninteracting bosons and fermions. To this scope a novel three-dimensional geometry for the waveguide circuit is introduced, which allows accurate polarization independent behavior, maintaining remarkable control on both phase and balancement. 相似文献
962.
Franciscus Jozef Vanhecke Antonio Roberto da Silva Cassio Sigaud 《Brazilian Journal of Physics》2012,42(5-6):471-474
In this short communication, we examine the relevance of the signature of the space-time metric in the construction of the product of a pseudo-Riemannian spectral triple with a finite triple describing the internal geometry. We obtain arguments favoring the appearance of SU(2) and U(1) as gage groups in the standard model. 相似文献
963.
P Zhang Y Hu D Cannan A Salandrino T Li R Morandotti X Zhang Z Chen 《Optics letters》2012,37(14):2820-2822
We study linear and nonlinear self-accelerating beams propagating along circular trajectories beyond the paraxial approximation. Such nonparaxial accelerating beams are exact solutions of the Helmholtz equation, preserving their shapes during propagation even under nonlinearity. We generate experimentally and observe directly these large-angle bending beams in colloidal suspensions of polystyrene nanoparticles. 相似文献
964.
Y Hu Z Sun D Bongiovanni D Song C Lou J Xu Z Chen R Morandotti 《Optics letters》2012,37(15):3201-3203
We demonstrate theoretically and experimentally that a finite Airy beam changes its trajectory while maintaining its acceleration in nonlinear photorefractive media. During this process, the spatial spectrum reshapes dramatically, leading to negative (or positive) spectral defects on the initial spectral distribution under a self-focusing (or defocusing) nonlinearity. 相似文献
965.
Vincenzo Piccialli Sabrina Zaccaria Roberto Centore Angela Tuzi Nicola Borbone Giorgia Oliviero Stefano D’Errico Valentina D’Atri 《Journal of chemical crystallography》2012,42(4):360-365
Abstract
The conformational arrangement of an all-threo bis-THF diol compound, synthesized through the RuO4-catalysed oxidative bis-cyclization of farnesyl acetate, was determined via crystallographic analysis and detailed 2D-NMR solution studies. The bis-THF compound crystallizes in the orthorhombic Pbca space group, with unit cell parameters a = 10.496(1), b = 17.974(1), c = 19.777(2) ?, Z = 8. The final refinement converged to R 1 = 0.0484 for 4714 independent observed reflections having I > 2σ(I). There is a good agreement between the solution molecular conformation determined by 2D-NMR and the X-ray molecular conformation. The molecule adopts a folded, horse shoe-type conformation both in solution and in the crystal, that suggests aptitude to coordinate cations. Additionally, in the crystals, the molecular conformation is stabilized by intramolecular and intermolecular H-bonding. 相似文献966.
Castriciano MA Romeo A Zagami R Micali N Scolaro LM 《Chemical communications (Cambridge, England)》2012,48(40):4872-4874
The kinetics of growth for chiral J-aggregates of H(4)TPPS(4) porphyrin have been investigated under different experimental conditions in the presence of tartaric acid. The observed rate constants and the anisotropy factor g show a defined dependence on the enantiomer used as a chiral templating agent. 相似文献
967.
Mashinsky VM Karatun NM Bogatyrev VA Sigaev VN Golubev NV Ignat'eva ES Lorenzi R Mozzati MC Paleari A Dianov EM 《Microscopy and microanalysis》2012,18(2):259-265
A spectroscopic protocol is proposed to implement confocal microfluorescence imaging to the analysis of microinhomogeneity in the nanocrystallization of the core of fibers belonging to a new kind of broadband fiber amplifier based on glass with embedded nanocrystals. Nanocrystallization, crucial for achieving an adequate light emission efficiency of transition metal ions in these materials, has to be as homogeneous as possible in the fiber to assure optical amplification. This requirement calls for a sensitive method for monitoring nanostructuring in oxide glasses. Here we show that mapping microfluorescence excited at 633 nm by a He-Ne laser may give a useful tool in this regard, thanks to quasi-resonant excitation of coordination defects typical of germanosilicate materials, such as nonbridging oxygens and charged Ge-O-Ge sites, whose fluorescence are shown to undergo spectral modifications when nanocrystals form into the glass. The method has been positively checked on prototypes of optical fibers--preventively characterized by means of scanning electron microscopy and energy dispersive spectroscopy--fabricated from preforms of Ni-doped Li?O-Na?O-Sb?O?-Ga?O?-GeO?-SiO? glass in silica cladding and subjected to heat treatment to activate gallium oxide nanocrystal growth. The method indeed enables not only the mapping of the crystallization degree but also the identification of drawing-induced defects in the fiber cladding. 相似文献
968.
Venturoni F Gioiello A Sardella R Natalini B Pellicciari R 《Organic & biomolecular chemistry》2012,10(20):4109-4115
A multi-gram scale protocol for the N-acyl amidation of bile acids with glycine and taurine has been successfully developed under continuous flow processing conditions. Selecting ursodeoxycholic acid (UDCA) as the model compound and N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) as the condensing agent, a modular mesoreactor assisted flow set-up was employed to significantly speed up the optimization of the reaction conditions and the flow scale-up synthesis. The results in terms of yield, in line purification, analysis, and implemented flow set-up for the reaction optimization and large scale production are reported and discussed. 相似文献
969.
Roberto A. Prado César R. de Oliveira 《Journal of Mathematical Analysis and Applications》2012,385(2):947-960
Some dynamical lower bounds for one-dimensional discrete Dirac operators with different classes of sparse potentials are presented, and the particular role of the particle mass is emphasized. 相似文献
970.
Let be an arbitrary integral domain, let be a multiset of elements of , let be a permutation of let be positive integers such that , and for let . We are interested in the problem of finding a block matrix with spectrum and such that for . Cravo and Silva completely characterized the existence of such a matrix when is a field. In this work we construct a solution matrix that solves the problem when is an integral domain with two exceptions: (i) ; (ii) , and for some .What makes this work quite unique in this area is that we consider the problem over the more general algebraic structure of integral domains, which includes the important case of integers. Furthermore, we provide an explicit and easy to implement finite step algorithm that constructs an specific solution matrix (we point out that Cravo and Silva’s proof is not constructive). 相似文献