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Magni M.,DellUniversity Milan | Colombo A.,DellUniversity Milan | Dragonetti C.,DellUniversity Milan | Dragonetti C.,CNR Institute of Molecular Science and Technologies | Mussini P.,DellUniversity Milan
Electrochimica Acta | Year: 2014

The present exhaustive electrochemical study proposes a rationalization of the redox properties of 1,10-phenanthroline-based copper complexes as a function of i) ligand molecular structure, evidencing the competition between electronic and steric effects of alkyl/aryl substituents, and ii) nature of working medium in terms of both solvent and supporting electrolyte anion. Occupancy of the 2 and 9 positions of the phenanthroline is a powerful tool to modulate the oxidation potentials of this family of complexes in a wide potential range. Solvent molecules play a key role in the metal-centred oxidative electron transfer process (unlike the optical electron transition), acting as ancillary ligands that allow the transition between tetrahedral four-coordinated Cu(I) state to tetragonal five-coordinated Cu(II). Actually clear evidences of the entry of one solvent molecule in the inner coordination sphere of the complexes are proved by the Kolthoff and Lingane method. Proof of ionic couple formation is also found. © 2014 Elsevier Ltd.

Dibitetto G.,University of Groningen | Klemm D.,DellUniversity Milan | Klemm D.,National Institute of Nuclear Physics, Italy
Journal of High Energy Physics | Year: 2010

We discuss the issue of how to include magnetic charges in the AdS 4 superalgebra osp(4|2). It is shown that the usual way of introducing a pseudoscalar central charge on the right hand side of the basic anticommutator does not work, because this breaks SO(2, 3) covariance. We propose a way out by promoting the magnetic charge to a vector charge, which amounts to enlarge osp(4|2) to the superconformal algebra su(2, 2|1). The conditions for 1/4, 1/2 and 3/4 BPS states are then analyzed. These states form the boundary of the convex cone associated with the Jordan algebra of 4×4 complex hermitian matrices. An Inönü-Wigner contraction of the constructed superalgebra yields a known extension of the Poincaré superalgebra containing electric and magnetic 0-brane charges as well as string- and space-filling 3-brane charges. As an example, we show how some supersymmetric AdS4 black holes fit into the classification scheme of BPS states.

Dragonetti C.,DellUniversity Milan | Dragonetti C.,CNR Institute of Molecular Science and Technologies | Colombo A.,DellUniversity Milan | Magni M.,DellUniversity Milan | And 10 more authors.
Inorganic Chemistry | Year: 2013

The synthesis of the new complex [Ru(Tetrazpy)(dcbpy)2]Cl is reported, along with its spectroscopical, electrochemical, and theoretical characterization. The first dye-sensitized solar cell device with this complex has been prepared, leading to a 3% of conversion efficiency, promising data considering the simplicity of the Tetrazpy ligand. © 2013 American Chemical Society.

Paavola J.,University of Turku | Hall M.J.W.,Australian National University | Paris M.G.A.,DellUniversity Milan | Maniscalco S.,University of Turku | Maniscalco S.,Heriot - Watt University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

The transition from quantum to classical, in the case of a quantum harmonic oscillator, is typically identified with the transition from a quantum superposition of macroscopically distinguishable states, such as the Schrödinger-cat state, into the corresponding statistical mixture. This transition is commonly characterized by the asymptotic loss of the interference term in the Wigner representation of the cat state. In this paper we show that the quantum-to-classical transition has different dynamical features depending on the measure for nonclassicality used. Measures based on an operatorial definition have well-defined physical meaning and allow a deeper understanding of the quantum-to-classical transition. Our analysis shows that, for most nonclassicality measures, the Schrödinger-cat state becomes classical after a finite time. Moreover, our results challenge the prevailing idea that more macroscopic states are more susceptible to decoherence in the sense that the transition from quantum to classical occurs faster. Since nonclassicality is a prerequisite for entanglement generation our results also bridge the gap between decoherence, which is lost only asymptotically, and entanglement, which may show a "sudden death." In fact, whereas the loss of coherences still remains asymptotic, we emphasize that the transition from quantum to classical can indeed occur at a finite time. © 2011 American Physical Society.

MacChi R.,DellUniversity Milan | Cariati E.,DellUniversity Milan | Marinotto D.,DellUniversity Milan | Roberto D.,DellUniversity Milan | And 6 more authors.
Journal of Materials Chemistry | Year: 2010

Poly(methyl methacrylate) (PMMA) films with 4 wt% of the ionic second order NLO chromophore [(E)-N,N-dimethylamino-N′-methylstilbazolium][p- toluenesulfonate] (DAST), obtained by spin-coating of CHCl3-CH 3OH (2/1) solutions, show in situ growth of homogeneously dispersed oriented nanocrystals with sizes of less than 100 nm, as supported by TEM and GIXRD evidence. This is achieved by a two step process: corona poling at 8 kV and 90 °C followed, in the absence of electric field, by controlled thermal annealing up to 140 °C. The final film shows a significant and enduring second harmonic generation (SHG) at room temperature. © 2010 The Royal Society of Chemistry.

Sparaciari C.,University College London | Sparaciari C.,DellUniversity Milan | Olivares S.,DellUniversity Milan | Olivares S.,National Institute of Nuclear Physics, Italy | And 2 more authors.
Journal of the Optical Society of America B: Optical Physics | Year: 2015

We address high-precision measurements by active and passive interferometric schemes based on Gaussian states and operations. In particular, we look for the best states to be injected into their ports according to the quantum Cramér-Rao bound, i.e., maximizing the quantum Fisher information over all the involved parameters, given a constraint on the overall mean number of photons entering into the interferometer. We found that for passive interferometers involving only beam splitters, the optimal input leading to Heisenberg scaling is a pair of identical squeezed-coherent states with at most one-third of the total energy employed in squeezing. For active interferometers involving optical amplifiers, input coherent signals are enough to achieve Heisenberg scaling, given an optimal value of the amplification gain. For passive schemes our results clarify the role of squeezing in improving both the reference phase and the signal phase of an interferometer. © 2015 Optical Society of America.

Brivio D.,DellUniversity Milan | Brivio D.,National Institute of Nuclear Physics, Italy | Cialdi S.,DellUniversity Milan | Cialdi S.,National Institute of Nuclear Physics, Italy | And 7 more authors.
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2010

We address estimation of one-parameter qubit gates in the presence of phase diffusion. We evaluate the ultimate quantum limits to precision, seek optimal probes and measurements, and demonstrate an optimal estimation scheme for polarization encoded optical qubits. An adaptive method to achieve optimal estimation in any working regime is also analyzed in detail and experimentally implemented. © 2010 The American Physical Society.

We perform calculations for the binding energies and low-lying levels of 10,11,12,13,14,15,16,17,18,19,20,21,22C nuclei starting from the chiral N3LO nucleon-nucleon potential within the framework of the Hybrid Multideterminant scheme. The effective interaction is obtained using the Lee-Suzuki renormalization scheme applied to 4 and in some cases to 5, major harmonic oscillator shells. The results are compared with the experimental data.

A simple and general prescription for evaluating unambiguously the sign of the grand canonical trace of quasi-particle statistical density operators (the so-called sign ambiguity in taking the square root of determinants) is given. Sign ambiguities of this kind appear in the evaluation of the grand canonical partition function projected to good quantum numbers (angular momentum, parity and particle number) in the Hartree-Fock-Bogoliubov approximation at finite temperature, since traces are usually expressed as the square root of determinants. A comparison is made with the numerical continuity method.

Puddu G.,Delluniversity Milan
European Physical Journal A | Year: 2015

Using the Argonne V18 interaction, renormalized with the Lee-Suzuki method, we study nuclei around the N = 20 island of inversion. We include 5 major oscillator shells, in a no-core approach, using the hybrid multi-determinant method reaching up to few hundreds Slater determinants. Although qualitatively in agreement with the experimental levels, the calculated BE2 do not show the same amount of collectivity seen experimentally. © 2015, SIF, Springer-Verlag Berlin Heidelberg.

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