Results for "Stefano Sanvito"

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Magnetic interaction of Co ions near the {10\bar{1}0} ZnO surfaceMar 12 2010Co-doped ZnO is the prototypical dilute magnetic oxide showing many of the characteristics of ferromagnetism. The microscopic origin of the long range order however remains elusive, since the conventional mechanisms for the magnetic interaction, such ... More
Magnetism of CoO polymorphsJan 07 2008Jul 01 2008A microscopic explanation for the room temperature ferromagnetism in diluted ZnO:Co is at present rather elusive. Although standard secondary phases can usually be ruled out, it is less clear whether regions with high Co concentration coexist with undoped ... More
A simple descriptor for energetics at fcc-bcc metal interfacesFeb 08 2018We develop a new and user-friendly method for calculating interface energies from first-principles. Our approach avoids problems that derive from the numerical differences between bulk and slab calculations, such as the number of k-points along the direction ... More
Wannier-function-based constrained DFT with nonorthogonality-correcting Pulay forces in application to the reorganization effects in graphene-adsorbed pentaceneFeb 05 2018Pulay terms arise in the Hellman-Feynman forces in electronic structure calculations when one employs a basis set made of localized orbitals that move with their host atoms. If the total energy of the system depends on a subspace population, defined in ... More
Multiprobe quantum spin Hall barsNov 28 2013Mar 11 2014We analyze electron transport in multiprobe quantum spin Hall (QSH) bars using the B\"{u}ttiker formalism and draw parallels with their quantum Hall (QH) counterparts. We find that in a QSH bar the measured resistance changes upon introducing side voltage ... More
Electron doping and magnetic moment formation in N- and C-doped MgOFeb 25 2009May 14 2009The formation of the magnetic moment in C- and N-doped MgO is the result of a delicate interplay between Hund's coupling, hybridization and Jahn-Teller distortion. The balance depends on a number of environmental variables including electron doping. We ... More
Accurate self-energy algorithm for quasi-1D systemsDec 09 2007We present a complete prescription for the numerical calculation of surface Green's functions and self-energies of semi-infinite quasi-onedimensional systems. Our work extends the results of Sanvito et al. [1] generating a robust algorithm to be used ... More
Dimensionality driven charge density wave instability in TiS$_2$Oct 07 2013Density functional theory and density functional perturbation theory are used to investigate the electronic and vibrational properties of TiS$_2$. Within the local density approximation the material is a semi-metal both in the bulk and in the monolayer ... More
Electric field control of valence tautomeric interconversion in Cobalt dioxoleneJan 25 2011We demonstrate that the critical temperature for valence tautomeric interconversion in Cobalt dioxolene complexes can be significantly changed when a static electric field is applied to the molecule. This is achieved by effectively manipulating the redox ... More
Dynamical Exchange Interaction From Time-Dependent Spin Density Functional TheoryJun 18 2013We report on {\it ab initio} time-dependent spin dynamics simulations for a two-center magnetic molecular complex based on time-dependent non-collinear spin density functional theory. In particular, we discuss how the dynamical behavior of the {\it ab ... More
Exploring the limits of the self consistent Born approximation for inelastic electronic transportApr 21 2008The non equilibrium Green function formalism is today the standard computational method for describing elastic transport in molecular devices. This can be extended to include inelastic scattering by the so called self-consistent Born approximation (SCBA), ... More
Spin-orbit Hamiltonian for organic crystals from first principles electronic structure and Wannier functionsNov 25 2016Spin-orbit coupling in organic crystals is responsible for many spin-relaxation phenomena, going from spin diffusion to intersystem crossing. With the goal of constructing effective spin-orbit Hamiltonians to be used in multiscale approaches to the thermodynamical ... More
Andreev reflection in two-dimensional topological insulators with either conserved or broken time-reversal symmetryFeb 22 2012Jul 19 2012We investigate Andreev reflection in two-dimensional heterojunctions formed by a superconductor in contact with a topological insulator ribbon either possessing or breaking time-reversal symmetry. Both classes of topological insulators exhibit perfect ... More
Spin-filtering efficiency of ferrimagnetic spinels CoFe2O4 and NiFe2O4Jan 11 2013We assess the potential of the ferrimagnetic spinel ferrites CoFe2O4 and NiFe2O4 to act as spin filtering barriers in magnetic tunnel junctions. Our study is based on the electronic structure calculated by means of first-principles density functional ... More
Ab initio study on the magneto-structural properties of MnAsJan 25 2006The magnetic and structural properties of MnAs are studied with ab initio methods, and by mapping total energies onto a Heisenberg model. The stability of the different phases is found to depend mainly on the volume and on the amount of magnetic order, ... More
Electron transport across electrically switchable magnetic moleculesMay 11 2009We investigate the electron transport properties of a model magnetic molecule formed by two magnetic centers whose exchange coupling can be altered with a longitudinal electric field. In general we find a negative differential conductance at low temperatures ... More
Resonant magnetoresistance in organic spin-valvesOct 31 2006We investigate theoretically the effects of surface states over the magnetoresistance of Ni-based organic spin-valves. In particular we perform {\it ab initio} electronic transport calculations for a benzene-thiolate molecule chemically attached to a ... More
Can half metallic zincblende MnAs be grown?Apr 11 2000In this paper we investigate theoretically the ground state NiAs-type structure of MnAs and we compare the magnetic and structural properties with an hypothetical zincblende structure. A zincblende structure can be obtained, in principle, from the diluted ... More
Contact-induced spin polarization in carbon nanotubesNov 28 2003Motivated by the possibility of combining spintronics with molecular structures, we investigate the conditions for the appearance of spin-polarization in low-dimensional tubular systems by contacting them to a magnetic substrate. We derive a set of general ... More
Ab-initio transport theory for digital ferromagnetic heterostructuresAug 25 2001MnAs/GaAs superlattices, made by $\delta$-doping GaAs with Mn, are known as digital ferromagnetic heterostructures. Here we present a theoretical density functional study of the electronic, magnetic and transport properties of such heterostructures. In ... More
Do As antisites destroy the ferromagnetism of (Ga,Mn)As?Nov 22 2000The effect of the inclusion of As antisites in the diluted magnetic semiconductor (Ga,Mn)As is studied within density functional theory in the local spin density approximation. In the case of homogeneous distribution of Mn ions we find that the ferromagnetism ... More
Molecular-Spintronics: the art of driving spin through moleculesMay 09 2006Spintronics is the ability of injecting, manipulating and detecting electron spins into solid state systems. Molecular-electronics investigates the possibility of making electronic devices using organic molecules. Traditionally these two burgeoning areas ... More
Detection of the electrostatic spin crossover effect in magnetic moleculesApr 17 2013Scanning tunneling microscopy (STM) can be used to detect inelastic spin transitions in magnetic nano-structures comprising only a handful of atoms. Here we demonstrate that STM can uniquely identify the electrostatic spin crossover effect, whereby the ... More
Spin-pumping and inelastic electron tunneling spectroscopy in topological insulatorsSep 07 2012Jun 07 2013We demonstrate that a quantum spin Hall current, spontaneously generated at the edge of a two-dimensional topological insulator, acts as a source of spin-pumping for a magnetic impurity with uniaxial anisotropy. One can then manipulate the impurity spin ... More
Topological surface states scattering in AntimonyJul 19 2012Nov 05 2012In this work we study the topologically protected states of the Sb(111) surface by using ab-initio transport theory. In the presence of a strong surface perturbation we obtain standing-wave states resulting from the superposition of spin-polarized surface ... More
The ground state of a spin-crossover molecule calculated by diffusion Monte CarloApr 24 2012Spin crossover molecules have recently emerged as a family of compounds potentially useful for implementing molecular spintronics devices. The calculations of the electronic properties of such molecules is a formidable theoretical challenge as one has ... More
Magnetism and Antiferroelectricity in MgB$_6$Mar 08 2012We report on a density functional theory study demonstrating the coexistence of weak ferromagnetism and antiferroelectricity in boron-deficient MgB6. A boron vacancy produces an almost one dimensional extended molecular orbital, which is responsible for ... More
Different origin of the ferromagnetic order in (Ga,Mn)As and (Ga,Mn)NJun 21 2004The mechanism for the ferromagnetic order of (Ga,Mn)As and (Ga,Mn)N is extensively studied over a vast range of Mn concentrations. We calculate the electronic structures of these materials using density functional theory in both the local spin density ... More
Self-interaction effects in (Ga,Mn)As and (Ga,Mn)NFeb 10 2003Jul 02 2004The electronic structures of Mn-doped zincblende GaAs and wurtzite GaN are calculated using both standard local-density functional theory (LSDA), and a novel pseudopotential self-interaction-corrected approach (pseudo-SIC), able to account for the effects ... More
Effects of edge chemistry doping on graphene nanoribbon mobilityJul 24 2011Doping of semiconductor is necessary for various device applications. Exploiting chemistry at its reactive edges was shown to be an effective way to dope an atomically thin graphene nanoribbon (GNR) for realizing new devices in recent experiments. The ... More
Phenomenology of Andreev reflection from first-principles transport theoryOct 27 2014We study Andreev reflection in normal metal-superconductor junctions by using an extended Blonder-Tinkham-Klapwijk model combined with transport calculations based on density functional theory. Starting from a parameter-free description of the underlying ... More
First principles study of the origin and nature of ferromagnetism in (Ga,Mn)AsNov 02 2000The properties of diluted Ga$_{1-x}$Mn$_x$As are calculated for a wide range of Mn concentrations within the local spin density approximation of density functional theory. M\"ulliken population analyses and orbital-resolved densities of states show that ... More
Non-equilibrium magnetic fields in ab initio spin dynamicsApr 21 2016Starting from the continuity equation for the magnetization in time-dependent spin-density functional theory, we derive an expression for the effective time-dependent magnetic fields driving the out-of-equilibrium spin dynamics in magnetic systems. We ... More
Charge carrier mobility in hybrid halide perovskitesNov 28 2014May 19 2015The charge transport properties of hybrid halide perovskites are investigated with a combination of density functional theory including van der Waals interaction and the Boltzmann theory for diffusive transport in the relaxation time approximation. We ... More
A pertubative approach to the Kondo effect in magnetic atoms on nonmagnetic substratesApr 14 2011Recent experimental advances in scanning tunneling microscopy make the measurement of the conductance spectra of isolated and magnetically coupled atoms on nonmagnetic substrates possible. Notably these spectra are characterized by a competition between ... More
The magnetism of wurtzite CoO nanoclustersAug 25 2009The possibility that the apparent room temperature ferromagnetism, often measured in Co-doped ZnO, is due to uncompensated spins at the surface of wurtzite CoO nanoclusters is investigated by means of a combination of density functional theory and Monte ... More
Gate controlled spin pumping at a quantum spin Hall edgeNov 28 2013We propose a four-terminal device designed to manipulate by all electrical means the spin of a magnetic adatom positioned at the edge of a quantum spin Hall insulator. We show that an electrical gate, able to tune the interface resistance between a quantum ... More
Resonant electronic states and I-V curves of Fe/MgO/Fe(100) tunnel junctionsAug 06 2008The bias dependence of the tunnel magnetoresistance (TMR) of Fe/MgO/Fe tunnel junctions is investigated theoretically with a fully self-consistent scheme that combines the non-equilibrium Green's functions method with density functional theory. At voltages ... More
The role of spin-orbit interaction in the ultrafast demagnetization of small iron clustersNov 03 2015The ultra-fast demagnetization of small iron clusters initiated by an intense optical excitation is studied with time-dependent spin density functional theory (TDSDFT). In particular we investigate the effect of the spin-orbit interaction on the onset ... More
Charge transfer energies of benzene physisorbed on a graphene sheet from constrained density functional theoryOct 27 2015Constrained density functional theory (CDFT) is used to evaluate the energy level alignment of a benzene molecule as it approaches a graphene sheet. Within CDFT the problem is conveniently mapped onto evaluating total energy differences between different ... More
Origin of the n-type and p-type conductivity of MoS2 monolayers on a SiO2 substrateJan 11 2013Ab-initio density functional theory calculations are performed to study the electronic properties of a MoS2 monolayer deposited over a SiO2 substrate in the presence of interface impurities and defects. When MoS2 is placed on a defect-free substrate the ... More
Spin-flip inelastic electron tunneling spectroscopy in atomic chainsMar 14 2011We present a theoretical study of the spin transport properties of mono-atomic magnetic chains with a focus on the spectroscopical features of the I-V curve associated to spin-flip processes. Our calculations are based on the s-d model for magnetism with ... More
Single atom anisotropic magnetoresistance on a topological insulator surfaceMay 12 2014Mar 15 2015We demonstrate single atom anisotropic magnetoresistance on the surface of a topological insulator, arising from the interplay between the helical spin-momentum-locked surface electronic structure and the hybridization of the magnetic adatom states. Our ... More
Electric Field Effects on Armchair MoS2 NanoribbonsAug 28 2013{\it Ab initio} density functional theory calculations are performed to investigate the electronic structure of MoS$_2$ armchair nanoribbons in the presence of an external static electric field. Such nanoribbons, which are nonmagnetic and semiconducting, ... More
Electrical control of spin dynamics in finite one-dimensional systemsJun 18 2011We investigate the possibility of the electrical control of spin transfer in monoatomic chains incorporating spin-impurities. Our theoretical framework is the mixed quantum-classical (Ehrenfest) description of the spin dynamics, in the spirit of the s-d-model, ... More
Spin-valve Effect in NiFe/MoS2/NiFe JunctionsFeb 22 2015Aug 15 2015Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have been recently proposed as appealing candidate materials for spintronic applications owing to their distinctive atomic crystal structure and exotic physical properties arising from ... More
Bias asymmetry in the conductance profile of magnetic ions on surfaces probed by scanning tunneling microscopyMar 28 2012The conductance profiles of magnetic transition metal atoms, such as Fe, Co and Mn, deposited on surfaces and probed by a scanning tunneling microscope (STM), provide detailed information on the magnetic excitations of such nano-magnets. In general the ... More
On the Newtonian origin of the spin motive force in ferromagnetic atomic wiresAug 08 2007Dec 10 2007We demonstrate numerically the existence of a spin-motive force acting on spin-carriers when moving in a time and space dependent internal field. This is the case of electrons in a one-dimensional wires with a precessing domain wall. The effect can be ... More
Current-driven magnetic rearrangements in spin-polarized point contactsMay 05 2005A new method for investigating the dynamics of atomic magnetic moments in current-carrying magnetic point contacts under bias is presented. This combines the non-equilibrium Green's function (NEGF) method for evaluating the current and the charge density ... More
Non-equilibrium magnetic fields in ab initio spin dynamicsApr 21 2016Nov 18 2016Starting from the continuity equation for the magnetization in time-dependent spin-density functional theory, we derive an expression for the effective time-dependent magnetic fields driving the out-of-equilibrium spin dynamics in magnetic systems. We ... More
Proximity induced topological state in grapheneJul 15 2014The appearance of topologically protected states at the surface of an ordinary insulator is a rare occurrence and to date only a handful of materials are known for having this property. An intriguing question concerns the possibility of forming topologically ... More
Ab-initio transport across Bismuth Selenide surface barriersMar 11 2014Dec 17 2014We investigate the effect of potential barriers in the form of step edges on the scattering properties of Bi$_2$Se$_3$(111) topological surface states by means of large-scale ab-initio transport simulations. Our results demonstrate the suppression of ... More
First-principles spin-transfer torque in CuMnAs$|$GaP$|$CuMnAs junctionsNov 22 2016We demonstrate that an all-antiferromagnetic tunnel junction with current perpendicular to the plane geometry can be used as an efficient spintronics device with potential high frequency operation. By using state-of-the-art density functional theory combined ... More
Current-induced energy barrier suppression for electromigration from first principlesJul 04 2011We present an efficient method for evaluating current-induced forces in nanoscale junctions, which naturally integrates into the non-equilibrium Green's function formalism implemented within density functional theory. This allows us to perform dynamical ... More
Coexistance of giant tunneling electroresistance and magnetoresistance in an all-oxide magnetic tunnel junctionFeb 22 2012We demonstrate with first-principles electron transport calculations that large tunneling magnetoresistance (TMR) and tunneling electroresistance (TER) effects can coexist in an all-oxide device. The TMR originates from the symmetry-driven spin filtering ... More
Strain-induced Weyl and Dirac states and direct-indirect gap transitions in group-V materialsJan 24 2018We perform comprehensive density-functional theory calculations on strained two-dimensional phosphorus (P), arsenic (As) and antimony (Sb) in the monolayer, bilayer, and bulk $\alpha$-phase, from which we compute the key mechanical and electronic properties ... More
Topological tuning in three-dimensional Dirac semimetalsAug 15 2014Dec 17 2014We study with first-principles methods the interplay between bulk and surface Dirac fermions in three dimensional Dirac semimetals. By combining density functional theory with the coherent potential approximation, we reveal a topological phase transition ... More
Large bias-dependent magnetoresistance in all-oxide magnetic tunnel junctions with a ferroelectric barrierOct 05 2010All-oxide magnetic tunnel junctions (MTJs) incorporating functional materials as insulating barriers have the potential of becoming the founding technology for novel multi-functional devices. We investigate, by first-principles density functional theory, ... More
Ab-initio study on the possible doping strategies for MoS$_2$ monolayersApr 30 2013Density functional theory is used to systematically study the electronic and magnetic properties of doped MoS$_2$ monolayers, where the dopants are incorporated both via S/Mo substitution or as adsorbates. Among the possible substitutional dopants at ... More
Molecular quantum phase transistorApr 01 2008Apr 17 2008This paper has been withdrawn by the authors due to some technical problems in the paper.
On-site approximation for spin-orbit coupling in LCAO density functional methodsJan 05 2006Oct 09 2007We propose a computational method that simplifies drastically the inclusion of spin-orbit interaction in density functional theory implemented on localised atomic orbital basis sets. Our method is based on a well-known procedure for obtaining pseudopotentials ... More
Efficient spin injection and giant magnetoresistance in Fe/MoS$_2$/Fe junctionsApr 14 2014Jul 15 2014We demonstrate giant magnetoresistance in Fe/MoS$_2$/Fe junctions by means of \textit{ab-initio} transport calculations. We show that junctions incorporating either a mono- or a bi-layer of MoS$_2$ are metallic and that Fe acts as an efficient spin injector ... More
Magneto-mechanical interplay in spin-polarized point contactsJan 10 2006We investigate the interplay between magnetic and structural dynamics in ferromagnetic atomic point contacts. In particular, we look at the effect of the atomic relaxation on the energy barrier for magnetic domain wall migration and, reversely, at the ... More
Electronic Transport Through EuO Spin Filter Tunnel JunctionsJul 09 2012Epitaxial spin filter tunnel junctions based on the ferromagnetic semiconductor europium monoxide, EuO, are investigated by means of density functional theory. In particular, we focus on the spin transport properties of Cu(100)/EuO(100)/Cu(100) junctions. ... More
Structural Origins of Conductance Fluctuations in Gold-Thiolate Molecular Transport JunctionsMar 01 2013We report detailed atomistic simulations combined with high-fidelity conductance calculations to probe the structural origins of conductance fluctuations in thermally evolving Au-benzene-1,4-dithiolate-Au junctions. We compare the behavior of structurally ... More
Electronic properties of bulk and thin film SrRuO$_3$: a search for the metal-insulator transitionJun 08 2008We calculate the properties of the 4$d$ ferromagnet SrRuO$_3$ in bulk and thin film form with the aim of understanding the experimentally observed metal to insulator transition at reduced thickness. Although the spatial extent of the 4$d$ orbitals is ... More
Revealing the role of organic cations in hybrid halide perovskites CH3NH3PbI3Oct 30 2014Jan 15 2015The hybrid halide perovskite CH$_{3}$NH$_{3}$PbI$_{3}$ has enabled solar cells to reach an efficiency of about 18\%, demonstrating a pace for improvements with no precedents in the solar energy arena. Despite such explosive progress, the microscopic origin ... More
Atomistic Simulations of Highly Conductive Molecular Transport Junctions Under Realistic ConditionsMar 20 2013We report state-of-the-art atomistic simulations combined with high-fidelity conductance calculations to probe structure-conductance relationships in Au-benzenedithiolate(BDT)-Au junctions under elongation. Our results demonstrate that large increases ... More
Ab-initio methods for spin-transport at the nanoscale levelMar 17 2005Apr 08 2005Recent advances in atomic and nano-scale growth and characterization techniques have led to the production of modern magnetic materials and magneto-devices which reveal a range of new fascinating phenomena. The modeling of these is a tough theoretical ... More
Ferromagnetism and metallic state in digital (Ga,Mn)As heterostructuresMay 27 2003We present an extensive density functional theory study of the electronic, magnetic and transport properties of GaAs and AlAs digital ferromagnetic heterostructures. These can be obtained by $\delta$-doping with Mn the GaAs layers of a GaAs/AlAs superlattice. ... More
Functionalized nanopore-embedded electrodes for rapid DNA sequencingAug 29 2007The determination of a patient's DNA sequence can, in principle, reveal an increased risk to fall ill with particular diseases [1,2] and help to design "personalized medicine" [3]. Moreover, statistical studies and comparison of genomes [4] of a large ... More
Atomic self-interaction correction for molecules and solidsSep 13 2006We present an atomic orbital based approximate scheme for self-interaction correction (SIC) to the local density approximation of density functional theory. The method, based on the idea of Filippetti and Spaldin [Phys. Rev. B 67, 125109 (2003)], is implemented ... More
On a quadratic functional for scalar conservation lawsNov 12 2013We prove a quadratic interaction estimate for approximate solutions to scalar conservation laws obtained by the wavefront tracking approximation or the Glimm scheme. This quadratic estimate has been used in the literature to prove the convergence rate ... More
Quantum Teleportation with Continuous Variables: a surveyApr 05 2006Oct 12 2006Very recently we have witnessed a new development of quantum information, the so-called continuous variable (CV) quantum information theory. Such a further development has been mainly due to the experimental and theoretical advantages offered by CV systems, ... More
Hydrodynamic Limit for an Anharmonic Chain under Boundary TensionFeb 06 2018We study the hydrodynamic limit for a one dimensional isothermal anharmonic finite chain in Lagrangian coordinates with hyperbolic space-time scaling. The temperature is kept constant by putting the chain in contact with a heat bath, realised via a stochastic ... More
Stretching of BDT-gold molecular junctions: thiol or thiolate termination?Oct 03 2014It is often assumed that the hydrogen atoms in the thiol groups of a benzene-1,4-dithiol dissociate when Au-benzene-1,4-dithiol-Au junctions are formed. We demonstrate, by stability and transport properties calculations, that this assumption can not be ... More
Femtosecond spin current pulses generated by the non-thermal spin-dependent Seebeck effect and interacting with ferromagnets in spin valvesJun 11 2016Jul 25 2016Using the sensitivity of magneto-induced second harmonic generation to spin currents (SC), we demonstrate in Fe/Au/Fe/MgO(001) pseudo spin valves the generation of 250 fs-long SC pulses. Their temporal profile indicates that superdiffusive hot electron ... More
Organised crime infiltration in the legitimate private economy - An empirical network analysis approachMar 20 2014It is estimated that Italian Mafias registered 135 billion euros in profits only in 2010. Part of this huge amount of money, coming mostly from the drugs, prostitution and arms illicit markets, is often used to invest into legitimate private economies. ... More
Stability of $L^\infty$ solutions for hyperbolic systems with coinciding shocks and rarefactionsJun 13 2000We consider a hyperbolic system of conservation laws u_t + f(u)_x = 0 and u(0,\cdot) = u_0, where each characteristic field is either linearly degenerate or genuinely nonlinear. Under the assumption of coinciding shock and rarefaction curves and the existence ... More
Divisorial models of normal varietiesNov 07 2012May 05 2015We prove that the canonical ring of a canonical variety in the sense of de Fernex and Hacon is finitely generated. We prove that canonical varieties are klt if and only if R(-K_X) is finitely generated. We introduce a notion of nefness for non-Q-Gorenstein ... More
Gauge boson couplings at LEPOct 14 2004A review is given of the measurements of triple and quartic couplings among the electroweak gauge bosons performed at LEP by the four experiments ALEPH, DELPHI, L3 and OPAL. Emphasis is placed on recently published results and on combinations of results ... More
A Quantum Teleportation GameJul 29 2004Nov 17 2004We investigate a game where a sender (Alice) teleports coherent states to two receivers (Bob and Charlie) through a tripartite Gaussian state. The aim of the receivers is to optimize their teleportation fidelities by means of local operations and classical ... More
Quantum Reading of a Classical Digital MemoryMar 17 2011We consider a basic model of digital memory where each cell is composed of a reflecting medium with two possible reflectivities. By fixing the mean number of photons irradiated over each memory cell, we show that a non-classical source of light can retrieve ... More
Chiral behaviour of the pion decay constant in $N_f=2$ QCDNov 13 2013Nov 25 2013As increased statistics and new ensembles with light pions have become available within the CLS effort, we complete previous work by inspecting the chiral behaviour of the pion decay constant. We discuss the validity of Chiral Perturbation Theory ($\chi$PT) ... More
GRB Afterglow Polarimetry: Past, Present and FutureJun 30 2009Gamma-ray bursts and their afterglows are thought to be produced by an ultrarelativistic jet. One of the most important open questions is the outflow composition: the energy may be carried out from the central source either as kinetic energy (of baryons ... More
Talbot self-imaging in $\mathcal{PT}$-symmetric complex crystalsSep 28 2014The Talbot effect, i.e. the self-imaging property of a periodic wave in near-field diffraction, is a remarkable interference phenomenon in paraxial systems with continuous translational invariance. In crystals, i.e. systems with discrete translational ... More
Many-body coherent destruction of tunneling in photonic latticesNov 15 2011An optical realization of the phenomenon of many-body coherent destruction of tunneling, recently predicted for interacting many-boson systems by Gong, Molina and Haenggi [Phys. Rev. Lett. 103, 133002 (2009)], is proposed for light transport in engineered ... More
Classical Simulation of Relativistic Quantum Mechanics in Periodic Optical StructuresNov 15 2011Spatial and/or temporal propagation of light waves in periodic optical structures offers a rather unique possibility to realize in a purely classical setting the optical analogues of a wide variety of quantum phenomena rooted in relativistic wave equations. ... More
Optical realization of the two-site Bose-Hubbard model in waveguide latticesJan 25 2011A classical realization of the two-site Bose-Hubbard Hamiltonian, based on light transport in engineered optical waveguide lattices, is theoretically proposed. The optical lattice enables a direct visualization of the Bose-Hubbard dynamics in Fock space. ... More
Low-frequency anomalies in dynamic localizationMay 11 2014Quantum mechanical spreading of a particle hopping on tight binding lattices can be suppressed by the application of an external ac force, leading to periodic wave packet reconstruction. Such a phenomenon, referred to as dynamic localization (DL), occurs ... More
Bound states in the continuum in PT-symmetric optical latticesFeb 16 2014Bound states in the continuum (BIC), i.e. normalizable modes with an energy embedded in the continuous spectrum of scattered states, are shown to exist in certain optical waveguide lattices with $\mathcal{PT}$-symmetric defects. Two distinct types of ... More
Quantum simulation of decoherence in optical waveguide latticesOct 27 2013We suggest that propagation of nonclassical light in lattices of optical waveguides can provide a laboratory tool to simulate quantum decoherence phenomena with high non-Markovian features. As examples, we study decoherence of optical Schr\"{o}dinger ... More
Invisibility in non-Hermitian tight-binding latticesAug 31 2010Reflectionless defects in Hermitian tight-binding lattices, synthesized by the intertwining operator technique of supersymmetric quantum mechanics, are generally not invisible and time-of-flight measurements could reveal the existence of the defects. ... More
Spatio-temporal wave propagation in photonic crystals: a Wannier-function analysisSep 02 2004A general analysis of undistorted propagation of localized wavepackets in photonic crystals based on a Wannier-function expansion technique is presented. Different kinds of propagating and stationary spatio-temporal localized waves are found from an asymptotic ... More
On the Number of Components of the Symplectic Representatives of the Canonical ClassNov 14 2006In this paper we show that there exists a family of simply connected, symplectic 4-manifolds such that the (Poincare dual of the) canonical class admits both connected and disconnected symplectic representatives. This answers a question raised by Fintushel ... More
Selective cloning of Gaussian states by linear opticsApr 23 2007We investigate the performances of a selective cloning machine based on linear optical elements and Gaussian measurements, which allows to clone at will one of the two incoming input states. This machine is a complete generalization of a 1 to 2 cloning ... More
A comment on anti-brane singularities in warped throatsFeb 16 2012We compute the imaginary self-dual (ISD) and imaginary anti-self-dual (IASD) fluxes for the Klebanov-Strassler background perturbed by a stack of p anti-D3 branes. We show that, at linear order in p, they both have a singularity in the near-brane region. ... More
Metastable Vacua and the Backreacted Stenzel GeometryOct 11 2011We construct an M-theory background dual to the metastable state recently discussed by Klebanov and Pufu, which corresponds to placing a stack of anti-M2 branes at the tip of a warped Stenzel space. With this purpose we analytically solve for the linearized ... More
Standard Model Higgs boson production and hard photon radiation in $e^+e^-\to μ^+μ^- b\bar bγ$ events at LEP II and Next Linear ColliderDec 22 1995Mar 28 1996We study at LEP II and Next Linear Collider energies Higgs production via the bremsstrahlung channel $e^+e^-\ar ZH$, with $Z\ar \mu^+\mu^-$ and $H\ar b\bar b$, and the corresponding irreducible background, in presence of hard photon radiation, both from ... More
Heavy Higgs production and decay via $e^+e^-\to Z^0 H^0 \to b\bar bZ^0Z^0$ and irreducible backgrounds at Next Linear CollidersJan 14 1995The complete matrix element for $e^+e^-\ar b\bar bZ^0Z^0$ has been computed at tree--level and applied to $Z^0H^0$--production followed by $Z^0\ar b\bar b$ and $H^0\ar Z^0Z^0$, including all the irreducible background, at Next Linear Colliders. We find ... More