Messanae Universitas Studiorum: No conditions. Results ordered -Date Deposited. 2017-02-21T17:03:51ZEPrintshttp://cab.unime.it/images/sitelogo.pnghttp://cab.unime.it/mus/2009-11-26Z2010-04-13T11:14:43Zhttp://cab.unime.it/mus/id/eprint/543This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5432009-11-26ZThermodynamics of semiconductors with impuritiesIn this paper we construct a geometric model for the thermodynamics of semiconductors with impurities, using a nonconventional model based on the extended irreversible thermodynamics with internal variables. For this purpose, we derive the transformation induced by the process and the dynamical system for a \textit{simple material element} of extrinsic semiconductors. Finally, we obtain the expressions for the entropy function, the necessary conditions for its existence and the entropy 1-form, starting point to investigate an extended thermodynamical phase space.Maria Paola MazzeoLiliana Restuccia2009-11-26Z2010-04-13T11:14:17Zhttp://cab.unime.it/mus/id/eprint/561This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5612009-11-26ZModelling dielectric relaxation with neural networksWe describe a software model for media with dielectric relaxation. In particular, a model identification is used to measure the phenomenological coefficients which occur in a mathematical description of dielectric relaxation phenomena in electromagnetic media. The identification is developed in order to substitute laboratory dielectric measurements on PMMA and PVC at different frequencies and at fixed temperature so as to obtain the phenomenological coefficients as a function of the frequency.Nicola Barbalace2009-11-26Z2010-04-13T11:14:50Zhttp://cab.unime.it/mus/id/eprint/541This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5412009-11-26ZThe absorbed energy in the Shroud body image formation appears as contributed by discrete valuesStarting from the optical density distribution in the Shroud body image and without any assumption on the mechanism that acts at a distance, we deduce that the absorbed energy by the Linen of Turin, related to the human body shape presence, is due to the contribution of discrete energy values.Giovanni FazioGiuseppe Mandaglio2009-11-26Z2010-04-13T11:14:29Zhttp://cab.unime.it/mus/id/eprint/551This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5512009-11-26ZIon acceleration enhancement in laser-generated plasmas by metallic doped hydrogenated polymersLaser-generated plasmas in vacuum were obtained by ablating hydrogenated polymers at the Physics Department of the University of Messina and at the PALS Laboratory in Prague. In the first case a 3 ns, 532 nm Nd:Yag laser, at 10^10 W/cm^2 intensity was employed. In the second case a 300 ps, 438 nm iodine laser, at 5x10^14 W/cm^2 intensity was employed. Different ion collectors were used in a time-of-flight configuration to monitor the ejected ions from the plasma at different angles with respect to the direction normal to the target surface. Measurements demonstrated that the mean ion velocity, directed orthogonally to the target surface, increases for ablation of polymers doped with metallic elements with respect to the nondoped one. The possible mechanism explaining the results can be found in the different electron density of the plasma, due to the higher number of electrons coming from the doping elements. This charge enhancement increases the equivalent ion voltage acceleration, i.e. the electric field generated in the non-equilibrium plasma placed in front of the ablated target surface.Lorenzo TorrisiAntonio BorrielliFrancesco CaridiAngela Maria Mezzasalma2009-11-26Z2010-04-13T11:14:24Zhttp://cab.unime.it/mus/id/eprint/553This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5532009-11-26ZDegenerated Bogdanov-Takens bifurcations in an immuno-tumor modelA mathematical immuno-tumor model proposed by A. Kavaliauskas [Nonlinear Anal. Model. Control 8, 55 (2003)] and consisting of a Cauchy problem for a system of two first-order ordinary differential equations is studied. For some particular parameters values, this model has saddle-node, Hopf and Bogdanov-Takens (BT) singularities. In the case of the BT singularities, we herein derive the normal forms of the governing equations by using ideas and a method from S.-N. Chow, C. Li, and D. Wang [Normal forms and bifurcation of planar vector fields (1994)] and Yu. A. Kuznetsov [Elements of applied bifurcation theory (1994)], based on an appropriate splitting of associated Hilbert spaces. It is found that a limit case of parameters associated with medicine administration corresponds to degenerate BT bifurcations and, so, to a large variety of responses to the medical treatments for admissible parameters near the limit ones.Mariana P. TrifanAdelina Georgescu2009-11-26Z2010-04-13T11:14:27Zhttp://cab.unime.it/mus/id/eprint/555This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5552009-11-26ZQuantum Biology A critical assessment of the recent developments of molecular biology is presented. The thesis that they do not lead to a conceptual understanding of life and biological systems is defended. Maturana and Varela's concept of autopoiesis is briefly sketched and its logical circularity avoided by postulating the existence of underlying living processes, entailing amplification from the microscopic to the macroscopic scale, with increasing complexity in the passage from one scale to the other. Following such a line of thought, the currently accepted model of condensed matter, which is based on electrostatics and short-ranged forces, is criticized. It is suggested that the correct interpretation of quantum dispersion forces (van der Waals, hydrogen bonding, and so on) as quantum coherence effects hints at the necessity of including long-ranged forces (or mechanisms for them) in condensed matter theories of biological processes. Some quantum effects in biology are reviewed and quantum mechanics is acknowledged as conceptually important to biology since without it most (if not all) of the biological structures and signalling processes would not even exist. Moreover, it is suggested that long-range quantum coherent dynamics, including electron polarization, may be invoked to explain signal amplification process in biological systems in general.Alessandro Sergi2009-11-25Z2010-04-13T11:15:16Zhttp://cab.unime.it/mus/id/eprint/522This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5222009-11-25ZMicroscopic theory of spatially resolved photoluminescence in disordered nanostructures Quantum dots have become objects of extensive research activity because of their applications such as advanced electronic and optoelectronic devices. Here we analyse theoretically the optical properties of dots naturally formed by interface fluctuations in GaAs narrow quantum wells. Specifically we present the simulations of local optical spectroscopy and spatially resolved photoluminescence in quantum wells with interface fluctuations. The theory includes light quantization, acoustic phonon scattering, and inhomogeneous sample-excitation and/or light-detection. Such theoretical framework provides a general basis for the description of spectroscopic imaging. Numerically calculated absorption and photoluminescence images clarify the impact of the near-field optical setup and put forward the potentials of the method for the understanding of near-field light emission from semiconductor quantum structures.
Salvatore SavastaGiovanna MartinoGiuseppe PistoneOmar Di StefanoRaffaello Girlanda2009-11-25Z2010-04-13T11:15:05Zhttp://cab.unime.it/mus/id/eprint/526This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5262009-11-25ZApplication possibilities of plasmas generated by high power laser ablation High-power pulsed lasers emitting IR and visible radiation with intensities ranging between 10^8 and 10^16 W/cm2, pulse duration from 0.4 to 9 ns and energy from 100 mJ up to 600 J, operating in single mode or in repetition rate, can be employed to produce non-equilibrium plasma in vacuum by irradiating solid targets. Such a laser-produced
plasma generates highly charged and high-energy ions of various elements, as well as soft and hard X-ray radiations. Heavy ions with charge state up to 58+ and kinetic energy up to 10 MeV are detected. The plasma emits ion current densities of the order of tens of mA/cm^2. Interesting application possibilities of the generated plasmas concerning the ion implantation technique, the laser ion sources, the high intensity and resolution X-ray
sources, the laser propulsion technique and the nuclear reaction of light elements are presented and discussed.Lorenzo Torrisi2009-11-25Z2010-04-13T11:14:58Zhttp://cab.unime.it/mus/id/eprint/533This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5332009-11-25ZIl metodo della fisica e le problematiche della biologia Following the ancient Hermetic aphorism solve et coagula, we investigate the nature of the interface between physics and biology by moving up and down the different temporal and spatial scales which enter the description of natural phenomena. Various indications seem to support both the existence of such an interface and the possibility of finding methods, languages, and targets shared by such two disciplines. However, this possibility becomes remote if one moves further and further from the microscopic level of atoms and molecules (and, correspondingly, of molecular biology). We conclude that the biologically founded epistemology proposed by Maturana and Varela as well as cultural anthropology and sociology cannot yet be treated with the methodology of physics.
Alessandro SergiGiacomo Tripodi2008-08-07Z2010-04-13T11:16:09Zhttp://cab.unime.it/mus/id/eprint/485This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4852008-08-07ZWhy so many "schools" of thermodynamics?A classification representing some main branches of phenomenological non-equilibrium thermodynamics is discussed. Differences and similarities of these selected branches are explained. Starting out with basic concepts of phenomenological thermodynamics, more developed theories with different back-grounds contributing to contemporary thermodynamics are considered. Because of its vast extent, this field cannot be presented completely in a single reasonably sized paper without any omissionsMuschik Wolfgang2008-08-07Z2010-04-13T11:16:00Zhttp://cab.unime.it/mus/id/eprint/487This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4872008-08-07ZOn special- and general-relativistic thermodynamics In reviewing approaches to the special- and general-relativistic theory of irreversible thermodynamical processes near equilibrium, problems of this procedure and possible solutions are discussedHorst-Heino Von BorzeszkowskiThoralf Chrobok2008-08-07Z2010-04-13T11:15:50Zhttp://cab.unime.it/mus/id/eprint/494This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4942008-08-07ZThermodynamic and mesoscopic modeling of tumbling nematics, of shear-thickening fluids and of stick-slip-like flow behavior Shear thickening, i.e. the increase of the viscosity with increasing shear rate as it occurs in dense colloidal dispersions and polymeric fluids is an intriguing phenomenon with a considerable potential for technical applications. The theoretical description of this phenomenon is patterned after the thermodynamic and mesoscopic modeling of the orientational dynamics and the flow behavior of liquid crystals in the isotropic and nematic phases, where the theoretical basis is well-established. Even there the solutions of the relevant equations recently yielded surprises: not only stable flow alignment and a periodic behavior (tumbling) are found as response to an imposed stationary shear flow but also irregular and chaotic dynamics occurs for certain parameter ranges. To treat shear-thickening fluids, a non-linear Maxwell model equation for the symmetric traceless part of the stress tensor has been proposed in analogy to the equations obeyed by the alignment tensor of nematics. The fluid-solid transition is formally analogous to the isotropic-nematic transition. In addition to shear-thickening and shear-thinning fluids, substances with yield stress can be modeled. Furthermore, periodic stick-slip-like motions and also chaotic behavior are found. In the latter cases, the instantaneous entropy production is not always positive. Yet it is comforting that its long-time average is in accord with the second law.
Siegfried HessSebastian HeidenreichPatrick IlgChris GoddardOrtwin Hess2008-08-07Z2010-04-13T11:15:40Zhttp://cab.unime.it/mus/id/eprint/499This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4992008-08-07ZOn the objectivity of time derivatiesA four-dimensional treatment of nonrelativistic space-time gives a natural frame to deal with objective time derivatives. In this framework some well known objective time derivatives of continuum mechanics appear as Lie-derivatives. Their coordinatized forms depends on the tensorial properties of the relevant physical quantitiesTamàs MatolcsiPéter Vàn2008-08-07Z2010-04-13T11:15:34Zhttp://cab.unime.it/mus/id/eprint/501This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5012008-08-07ZNonlocal and rotational effects in quantum turbulence We discuss phenomenological equations for the evolution of vortex tangle in counterflow superfluid turbulence, which takes into account the influence of the non local effects, both in absence and in the presence of rotation. Maria Stella MongiovìDavid Jou2008-08-07Z2010-04-13T11:15:30Zhttp://cab.unime.it/mus/id/eprint/504This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5042008-08-07ZMesoscopic non-equilibrium thermodynamics
Basic concepts like energy, heat, and temperature have acquired a precise meaning after the development of thermodynamics. Thermodynamics provides the basis for understanding how heat and work are related and with the general rules that the macroscopic properties of systems at equilibrium follow. Outside equilibrium and away from macroscopic regimes most of those rules cannot be applied directly. In this paper we present recent developments that extend the applicability of thermodynamic concepts deep into mesoscopic and irreversible regimes. We show how the probabilistic interpretation of thermodynamics together with probability conservation laws can be used to obtain kinetic equations describing the evolution of the relevant degrees of freedom. This approach provides a systematic method to obtain the stochastic dynamics of a system directly from the knowledge of its equilibrium properties. A wide variety of situations can be studied in this way, including many that were thought to be out of reach of thermodynamic theories, such as non-linear transport in the presence of potential barriers, activated processes, slow relaxation phenomena, and basic processes in biomolecules, like translocation and stretchingJosé Miguel Rubi2008-08-07Z2010-04-13T11:15:33Zhttp://cab.unime.it/mus/id/eprint/506This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5062008-08-07ZThermodynamic extremal principle and its application to Dufour and Soret effects and plasticity An extremal principle is formulated for thermodynamic systems near equilibrium subjected to various external conditions. It is shown that the principle describes unambiguously the kinetics of the thermodynamic system and replaces classical phenomenological equations. Thus the principle can be considered as an effective tool for the treatment of non-equilibrium thermodynamic systems. In two examples the principle is used for the description of Dufour and Soret effects and plasticityJirì SvobodaFranz Dieter FischerJirì Vala2008-08-07Z2010-04-13T11:16:06Zhttp://cab.unime.it/mus/id/eprint/484This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4842008-08-07ZNon equilibrium thermodynamics with internal variables in Kluitenberg's theory
We show a method to verify experimentally some inequalities which occur for phenomenological coefficients in the thermodynamical model for dielectric relaxation and viscoanelastic media developed in the ambit of non-equilibrium thermodynamic Kluitenberg's theory. In particular, for dielectric relaxation we assume a sinusoidal form for induction vector (extensive variable: cause), the electric field (intensive variable: effect) inside the system, which depends on unknown phenomenological coefficients, has been obtained by integration. Then we compare it with a similar form of the electric field obtained by experimental considerations, where well known experimentally determinable coefficients appear. We carry out dielectric measurements on PMMA and PVC at different frequencies and fixed temperature in order to obtain the phenomenological coefficients as functions of the frequency. For viscoanelastic media we consider the relative rheological equation and we compare the solution of this equation with a well known expression of the stress obtained, by experimentally considerations, in the linear response theory. This comparison will be able to determine the phenomenological an state coefficients as function of frequency dependent quantities experimentally measurable. This method will be applied to polymeric materials as Polyisobutilene.
Vincenzo Ciancio2008-08-07Z2010-04-13T11:15:58Zhttp://cab.unime.it/mus/id/eprint/486This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4862008-08-07ZQuantum thermodynamics: microscopic foundations of entropy and of entropy generation by irreversibility What is the physical significance of entropy? What is the physical origin of irreversibility? Do entropy and irreversibility exist only for complex and macroscopic systems?
Most physicists still accept and teach that the rationalization of these fundamental questions is given by Statistical Mechanics. Indeed, for everyday laboratory physics, the mathematical formalism of Statistical Mechanics (canonical and grand-canonical, Boltzmann, Bose-Einstein and Fermi-Dirac distributions) allows a successful description of the thermodynamic equilibrium properties of matter, including entropy values. However, as already recognized by SchrÃ¶dinger in 1936, Statistical Mechanics is impaired by conceptual ambiguities and logical inconsistencies, both in its explanation of the meaning of entropy and in its implications on the concept of state of a system.
An alternative theory has been developed by Gyftopoulos, Hatsopoulos and the present author to eliminate these stumbling conceptual blocks while maintaining the mathematical formalism so successful in applications. To resolve both the problem of the meaning of entropy and that of the origin of irreversibility we have built entropy and irreversibility into the laws of microscopic physics. The result is a theory, that we call Quantum Thermodynamics, that has all the necessary features to combine Mechanics and Thermodynamics uniting all the successful results of both theories, eliminating the logical inconsistencies of Statistical Mechanics and the paradoxes on irreversibility, and providing an entirely new perspective on the microscopic origin of irreversibility, nonlinearity (therefore including chaotic behavior) and maximal-entropy-generation nonequilibrium dynamics.
In this paper we discuss the background and formalism of Quantum Thermodynamics including its nonlinear equation of motion and the main general results. Our objective is to show in a not-too-technical manner that this theory provides indeed a complete and coherent resolution of the century-old dilemma on the meaning of entropy and the origin of irreversibility, including Onsager reciprocity relations and maximal-entropy-generation nonequilibrium dynamics, which we believe provides the microscopic foundations of heat, mass and momentum transfer theories, including all their implications such as Bejan's Constructal Theory of natural phenomena.
Gian Paolo Beretta2008-08-07Z2010-04-13T11:16:01Zhttp://cab.unime.it/mus/id/eprint/488This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4882008-08-07ZSuperpositions in Prigogine's approach to irreversibility for physical and financial applications In this paper we apply the theory of superpositions for Radon measures on compact subsets of the real Euclidean n-space Rn to Prigogine's approach in the study of irreversible processes, which emerge in physics and in economics, showing that the superposition is a natural rigorous tool feasible to face the problemDavid Carfì2008-08-07Z2010-04-13T11:15:55Zhttp://cab.unime.it/mus/id/eprint/491This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4912008-08-07ZNon-equilibrium thermodynamics with higher order fluxes: Balance laws and exploitation of the entropy inequality Weakly non-local extended thermodynamics of rigid heat conductors is presented. The two celebrated procedures by Coleman-Noll and Liu for the exploitation of second law of thermodynamics are compared. It is proved that the two procedures are equivalent, if in the Coleman-Noll procedure all relevant equations are taken into account as constraintsVito Antonio CimmelliWolfgang MuschikVita Triani2008-08-07Z2010-04-13T11:15:48Zhttp://cab.unime.it/mus/id/eprint/493This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4932008-08-07ZClose-to-Fourier heat conduction equation for solids: Motivation and symbolic-numerical analysis Heat conduction close-to-Fourier means, that we look for a minimal extension of heat conduction theory using the usual Fourier expression of the heat flux density and modifying that of the internal energy as minimal as possible by choosing the minimal state space. Applying Liu's procedure results in the class of materials and a differential equation both belonging to the close-to-Fourier case of heat conduction. A symbolic-numerical computing method is applied to approximate the numerical solutions of 2 special heat conduction equations belonging to the close-to-Fourier classHeiko HerrmannHong GuGunnar RücknerJurgent SiebertWolfgang Muschik2008-08-07Z2010-04-13T11:15:43Zhttp://cab.unime.it/mus/id/eprint/496This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4962008-08-07ZTemperature component method for heat conduction problems The work includes a solving proposal for initial-boundary value 3D heat conduction problems. The proposal is based on an extension of the body model region to the whole space where the space integral as a particular solution to the initial-boundary value problem is derived. Temperature component is separated from the space integral. The component admissibility conditions are formulated. For numerical purposes the approximated integral with a discrete set of fictitious components is proposed. The fictitious component intensities are determined on an approximate way from the boundary condition. An approximate solution of the heat conduction problem is obtained by extension in time and contraction in space of the approximated integralJanusz Jankowski2008-08-07Z2010-04-13T11:15:47Zhttp://cab.unime.it/mus/id/eprint/498This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4982008-08-07ZA stress field in the vortex lattice in the type-II superconductor Magnetic flux can penetrate a type-II superconductor in the form of Abrikosov vortices (also called flux lines, flux tubes, or fluxons), each carrying a quantum of magnetic flux. These tiny vortices of supercurrent tend to arrange themselves in a triangular and/or quadratic flux-line lattice, which is more or less perturbed by material inhomogeneities that pin the flux lines. Pinning is caused by imperfections of the crystal lattice, such as dislocations, point defects, grain boundaries, etc. Hence, a honeycomb-like pattern of the vortex array presents some mechanical properties. If the Lorentz force of interactions between the vortices is much bigger than the pinning force, the vortex lattice behaves elastically. So we assume that the pinning force is negligible in the sequel and we deal with soft vortices. The vortex motion in the vortex lattice and/or creep of the vortices in the vortex fluid is accompanied by energy dissipation. Hence, except for the elastic properties, the vortex field is also of a viscous character. The main aim of the paper is a formulation of a thermoviscoelastic stress - strain constitutive law consisted of coexistence of the ordered and disordered states of the vortex field. Its form describes an auxetic-like thermomechanical (anomalous) property of the vortex field.
Bogdan Maruszewski2008-08-07Z2012-09-20T08:30:34Zhttp://cab.unime.it/mus/id/eprint/500This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5002008-08-07ZIntroduction to the thermomechanics of configurational forces
Configurational forces are thermodynamic conjugates to irreversible material body evolutions such as extension of cracks, progress of phase-transition fronts, movement of shock waves, etc. They do correspond to a change of material configuration. Accordingly, their realm is the material manifold of a body. Furthermore, they acquire a physical meaning only in so far as they contribute to the global dissipation. Therefore, the present contribution of a pedagogical nature proposes a primer introduction to the thermodynamics of configurational forces. To that purpose, we first introduce a consistent thermomechanics of general deformable continua on the material manifold (and not in physical space). This is achieved in a canonical manner by full projection of the balance equation of momentum onto the material manifold and constructing in parallel a formally consistent expression of the energy conservation. Then various configurational forces such as those appearing in inhomogeneous bodies, at the tip of a propagating crack, at the surface of a propagating phase-transition front, or of a shock wave, and those due to local structural rearrangements (plasticity, damage, growth), are examined from the point of view of their dissipated powerGérard A. MauginArkadi Berezovski2008-08-07Z2010-04-13T11:15:37Zhttp://cab.unime.it/mus/id/eprint/502This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5022008-08-07ZWaves propagation in superfluid helium in presence of combined rotation and counterflow Using the linear macroscopic mono-fluid model of liquid helium II, in which the fundamental fields are the density ?, the velocity v, the temperature T and heat flux q and taking into account the expression of an additional pressure tensor Pw, introduced to describe phenomena linked to vortices, a complete study of wave propagation is made in the complex situation involving thermal counterflow in a rotating cylinderRosa Anna PeruzzaMichele Sciacca2008-08-07Z2010-04-13T11:15:32Zhttp://cab.unime.it/mus/id/eprint/505This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5052008-08-07ZAction of a heat source and influence of initial condition on the plane state of temperature The work takes an advantage of the temperature component method for some heat conduction problems. Simplifications of the method for 2D problems are considered. Some examples of calculations are quotedRoman StarostaTomasz WalczakJanusz Jankowski2008-08-07Z2010-04-13T11:15:27Zhttp://cab.unime.it/mus/id/eprint/507This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5072008-08-07ZWhite areas on the map of applying non-equilibrium thermodynamics: On the self accelerating electron Classical electrodynamics displays a formula for the equation of the motion of charged particles that has run away solutions. Gyarmati's wave approach leads to a solution fitting to the classical term in the low frequency regime. A shortage of the solution is that the characteristic time in the equation depends on the mass of the charged particle. An abstract model with two dynamic degrees of freedom results in a solution free of the above problem. For complete compatibility with electrodynamics, the need for a generalization of Maxwell's equations is probableJòzsef Verhàs2008-08-07Z2010-04-13T11:15:38Zhttp://cab.unime.it/mus/id/eprint/503This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/5032008-08-07ZIndefinite metric of R. Mrugala and the geometry of thermodynamical phase space We study an indefinite metric G which was introduced by R. Mrugala and is defined on the contact phase space (P,?) of a homogeneous thermodynamical system. We describe the curvature properties and the isometry group of the metric G. We established an isomorphism of the space (P,?,G) with the Heisenberg Lie group Hn, endowed with the right invariant contact structure and the right invariant indefinite metric. The lift of the metric G to the symplectization of contact space (P,?) and its properties are studied. Finally we introduce the "hyperbolic projectivization" of the space () that can be considered as the natural compactification of the thermodynamical phase space (P, q, G).
Serge PrestonJames Vargo2008-08-07Z2010-04-13T11:15:45Zhttp://cab.unime.it/mus/id/eprint/497This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4972008-08-07ZHeat and mass transfer across phase boundaries: Estimates of coupling coefficients Heat and mass transport across phase boundaries are central in many engineering problems. The systematic description offered by classical non-equilibrium thermodynamics theory, when extended to surfaces, gives the interaction between the two fluxes in terms of coupling coefficients. It is shown in this paper that these coupling coefficients are large. The few experimental and computational results that are available confirm this. Neglect of coupling coefficients, which is common in most models for surface transport, may lead to errors in the heat flux. We present values for the coupling coefficient in a one-component system in terms of the heat of transfer, as obtained from non-equilibrium molecular dynamics simulations, kinetic theory and the integrated non-equilibrium van der Waals' square gradient modelSigne KjelstrupDick Bedeaux2008-08-07Z2010-04-13T11:15:51Zhttp://cab.unime.it/mus/id/eprint/495This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4952008-08-07ZAn introduction to endoreversible thermodynamics Reversible thermodynamic processes are convenient abstractions of real processes, which are always irreversible. Approaching the reversible regime means to become more and more quasistatic, letting behind processes which achieve any kind of finite transformation rate for the quantities studied. On the other hand studying processes with finite transformation rates means to deal with irreversibilities and in many cases these irreversibilities must be included in a realistic description of such processes. Endoreversible thermodynamics is a non-equilibrium approach in this direction by viewing a system as a network of internally reversible (endoreversible) subsystems exchanging energy in an irreversible fashion. This material provides an introduction to the subjectKarl Heinz Hoffmann2008-08-07Z2010-04-13T11:15:56Zhttp://cab.unime.it/mus/id/eprint/492This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4922008-08-07ZThermodynamics of heterogeneous and anisotropic nonlinear ferroelastic crystals In a previous paper, in a geometrized framework for the description of simple materials with internal variables, the specific example of ferroelastic crystals with anisotropy grain-tensors Ã la Maruszewski was considered and the relevant structure of the entropy 1-form was derived. In this contribution the linear morphism defined on the fibre bundle of the process and the transformation induced by the process are obtained as new results within the geometrical model. Furthermore, Clausius-Duhem inequality for these media is exploited, and, using a Maugin technique (see also Colemann-Noll procedure), the laws of state, the extra entropy flux and the residual dissipation inequality are worked out. Finally, following Maugin, the heat equation in the first and the second form are derived.
Mauro FrancavigliaLiliana Restuccia2008-08-07Z2012-09-20T07:41:27Zhttp://cab.unime.it/mus/id/eprint/490This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4902008-08-07ZExtended irreversible thermodynamics and non-equilibrium temperatureWe briefly review the concept of non-equilibrium temperature from the perspectives of extended irreversible thermodynamics, fluctuation theory, and statistical mechanics. The relations between different proposals are explicitly examined in two especially simple systems: an ideal gas in steady shear flow and a forced harmonic oscillator in a thermal bath. We examine with special detail temperatures related to the average molecular kinetic energy along different spatial directions, to the average configurational energy, to the derivative of the entropy with respect to internal energy, to fluctuation-dissipation relation and discuss their measurementJosè Casas-VàzquezDavid Jou2008-04-23Z2010-04-13T11:16:12Zhttp://cab.unime.it/mus/id/eprint/479This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4792008-04-23ZA novel probe fabrication process for improvement in scanning near-field optical microscopy The full exploitation of the microscope potentialities as surface science tool on nanometer scale strictly depends on the probe features. Recent developments on fiber probes for Scanning Near Field Optical Microscope are reported. In this frame, new models and prototypes of probes with higher performances in terms of optical power efficiency and polarization selectivity are worked out. A new fabrication method of the probes is settled, based on a chemical etching process, which doubles the aspect ratio of the probe sharpness and improves the optical throughput. Moreover, Finite Domain Time Difference simulation allows the designing of a probe able to act as an evanescent field linear polarizer.
Eugenio Cefalì2008-03-03Z2010-04-13T11:16:22Zhttp://cab.unime.it/mus/id/eprint/475This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4752008-03-03ZElastic wavelets and their application to problems of solitary wave propagation
The paper can be referred to that direction in the wavelet theory, which was called by Kaiser "the physical wavelets". He developed the analysis of first two kinds of physical wavelets - electromagnetic (optic) and acoustic wavelets. Newland developed the technique of application of harmonic wavelets especially for studying the harmonic vibrations. Recently Cattani and Rushchitsky proposed the 4th kind of physical wavelets - elastic wavelets. This proposal was based on three main elements: 1. Kaiser's idea of constructing the physical wavelets on the base of specially chosen (admissible) solutions of wave equations. 2. Developed by one of authors theory of solitary waves (with profiles in the form of Chebyshov-Hermite functions) propagated in elastic dispersive media. 3. The theory and practice of using the wavelet "Mexican Hat" system, the mother and farther wavelets (and their Fourier transforms) of which are analytically represented as the Chebyshov-Hermite functions of different indexes. An application of elastic wavelets to studying the evolution of solitary waves of different shape during their propagation through composite materials is shown on many examples.
Jeremiah RushchitskyCarlo CattaniKatherina TerletskaYaroslav Symchuk2008-03-03Z2010-04-13T11:16:20Zhttp://cab.unime.it/mus/id/eprint/474This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4742008-03-03ZSulla sesta distorsione elementare di Volterra per un cilindro cavo omogeneo e isotropo di altezza finita con carico alla Saint VenantIn this work we consider the sixth elementary Volterra's distortion for a circular hollow, homogeneous, elastic, isotropic cylinder, to analyze the load acting on the bases as a Saint Venant characteristic external stress. In this way we are able to prove that the specific load connected to the sixth distortion and examined as external stress, is equivalent (in Saint Venant's theory) to a right combined compressive and bending stress (or to a right combined tensile and bending stress).
I BochicchioE LaserraM Pecoraro2008-01-28Z2010-04-13T11:16:42Zhttp://cab.unime.it/mus/id/eprint/463This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4632008-01-28ZA stress field in the vortex lattice in the type-II superconductor Magnetic flux can penetrate a type-II superconductor in the form of Abrikosov vortices (also called flux lines, flux tubes, or fluxons), each carrying a quantum of magnetic flux. These tiny vortices of supercurrent tend to arrange themselves in a triangular and/or quadratic flux-line lattice, which is more or less perturbed by material inhomogeneities that pin the flux lines. Pinning is caused by imperfections of the crystal lattice, such as dislocations, point defects, grain boundaries, etc. Hence, a honeycomb-like pattern of the vortex array presents some mechanical properties. If the Lorentz force of interactions between the vortices is much bigger than the pinning force, the vortex lattice behaves elastically. So we assume that the pinning force is negligible in the sequel and we deal with soft vortices. The vortex motion in the vortex lattice and/or creep of the vortices in the vortex fluid is accompanied by energy dissipation. Hence, except for the elastic properties, the vortex field is also of a viscous character. The main aim of the paper is a formulation of a thermoviscoelastic stress - strain constitutive law consisted of coexistence of the ordered and disordered states of the vortex field. Its form describes an auxetic-like thermomechanical (anomalous) property of the vortex field.Bogdan Maruszewski2008-01-28Z2010-04-13T11:16:24Zhttp://cab.unime.it/mus/id/eprint/470This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4702008-01-28ZAction of a heat source and influence of initial condition on the plane state of temperature The work takes an advantage of the temperature component method for some heat conduction problems. Simplifications of the method for 2D problems are considered. Some examples of calculations are quoted.
Roman StarostaTomasz WalczakJanusz Jankowski2008-01-28Z2010-04-13T11:16:27Zhttp://cab.unime.it/mus/id/eprint/472This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4722008-01-28ZWhite areas on the map of applying non-equilibrium thermodynamics: On the self accelerating electron Classical electrodynamics displays a formula for the equation of the motion of charged particles that has run away solutions. Gyarmati's wave approach leads to a solution fitting to the classical term in the low frequency regime. A shortage of the solution is that the characteristic time in the equation depends on the mass of the charged particle. An abstract model with two dynamic degrees of freedom results in a solution free of the above problem. For complete compatibility with electrodynamics, the need for a generalization of Maxwell's equations is probable.
Jòzsef Verhàs2008-01-28Z2012-09-20T08:35:55Zhttp://cab.unime.it/mus/id/eprint/451This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4512008-01-28ZWhy so many "Schools" of Thermodynamics?A classification representing some main branches of phenomenological non-equilibrium thermodynamics is discussed. Differences and similarities of these selected branches are explained. Starting out with basic concepts of phenomenological thermodynamics, more developed theories with different back-grounds contributing to contemporary thermodynamics are considered. Because of its vast extent, this field cannot be presented completely in a single reasonably sized paper without any omissions.Wolfgang Muschik2008-01-28Z2013-04-03T09:54:13Zhttp://cab.unime.it/mus/id/eprint/453This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4532008-01-28ZOn special- and general-relativistic thermodynamics In reviewing approaches to the special- and general-relativistic theory of irreversible thermodynamical processes near equilibrium, problems of this procedure and possible solutions are discussed. Horst-Heino Von BorzeszkowskiThoralf Chrobok2008-01-28Z2012-09-20T08:21:46Zhttp://cab.unime.it/mus/id/eprint/455This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4552008-01-28ZExtended irreversible thermodynamics and non-equilibrium temperature We briefly review the concept of non-equilibrium temperature from the perspectives of extended irreversible thermodynamics, fluctuation theory, and statistical mechanics. The relations between different proposals are explicitly examined in two especially simple systems: an ideal gas in steady shear flow and a forced harmonic oscillator in a thermal bath. We examine with special detail temperatures related to the average molecular kinetic energy along different spatial directions, to the average configurational energy, to the derivative of the entropy with respect to internal energy, to fluctuation-dissipation relation and discuss their measurement. Josè Casas-VàzquezDavid Jou2008-01-28Z2010-04-13T11:16:47Zhttp://cab.unime.it/mus/id/eprint/460This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4602008-01-28ZAn introduction to endoreversible thermodynamics Reversible thermodynamic processes are convenient abstractions of real processes, which are always irreversible. Approaching the reversible regime means to become more and more quasistatic, letting behind processes which achieve any kind of finite transformation rate for the quantities studied. On the other hand studying processes with finite transformation rates means to deal with irreversibilities and in many cases these irreversibilities must be included in a realistic description of such processes. Endoreversible thermodynamics is a non-equilibrium approach in this direction by viewing a system as a network of internally reversible (endoreversible) subsystems exchanging energy in an irreversible fashion. This material provides an introduction to the subject. Karl Heinz Hoffmann2008-01-28Z2010-04-13T11:16:34Zhttp://cab.unime.it/mus/id/eprint/464This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4642008-01-28ZOn the objectivity of time derivaties A four-dimensional treatment of nonrelativistic space-time gives a natural frame to deal with objective time derivatives. In this framework some well known objective time derivatives of continuum mechanics appear as Lie-derivatives. Their coordinatized forms depends on the tensorial properties of the relevant physical quantities. Tamàs MatolcsiPéter Vàn2008-01-28Z2010-04-13T11:16:37Zhttp://cab.unime.it/mus/id/eprint/466This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4662008-01-28ZNonlocal and rotational effects in quantum turbulenceWe discuss phenomenological equations for the evolution of vortex tangle in counterflow superfluid turbulence, which takes into account the influence of the non local effects, both in absence and in the presence of rotation.
Maria Stella MongiovìDavid Jou2008-01-28Z2010-04-13T11:16:32Zhttp://cab.unime.it/mus/id/eprint/469This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4692008-01-28ZMesoscopic non-equilibrium thermodynamics Basic concepts like energy, heat, and temperature have acquired a precise meaning after the development of thermodynamics. Thermodynamics provides the basis for understanding how heat and work are related and with the general rules that the macroscopic properties of systems at equilibrium follow. Outside equilibrium and away from macroscopic regimes most of those rules cannot be applied directly. In this paper we present recent developments that extend the applicability of thermodynamic concepts deep into mesoscopic and irreversible regimes. We show how the probabilistic interpretation of thermodynamics together with probability conservation laws can be used to obtain kinetic equations describing the evolution of the relevant degrees of freedom. This approach provides a systematic method to obtain the stochastic dynamics of a system directly from the knowledge of its equilibrium properties. A wide variety of situations can be studied in this way, including many that were thought to be out of reach of thermodynamic theories, such as non-linear transport in the presence of potential barriers, activated processes, slow relaxation phenomena, and basic processes in biomolecules, like translocation and stretching.
José Miguel Rubi2008-01-28Z2010-04-13T11:16:25Zhttp://cab.unime.it/mus/id/eprint/471This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4712008-01-28ZThermodynamic extremal principle and its application to Dufour and Soret effects and plasticity
An extremal principle is formulated for thermodynamic systems near equilibrium subjected to various external conditions. It is shown that the principle describes unambiguously the kinetics of the thermodynamic system and replaces classical phenomenological equations. Thus the principle can be considered as an effective tool for the treatment of non-equilibrium thermodynamic systems. In two examples the principle is used for the description of Dufour and Soret effects and plasticity.
Jirì SvobodaFranz Dieter FischerJirì Vala2008-01-28Z2010-04-13T11:16:38Zhttp://cab.unime.it/mus/id/eprint/461This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4612008-01-28ZTemperature component method for heat conduction problems The work includes a solving proposal for initial-boundary value 3D heat conduction problems. The proposal is based on an extension of the body model region to the whole space where the space integral as a particular solution to the initial-boundary value problem is derived. Temperature component is separated from the space integral. The component admissibility conditions are formulated. For numerical purposes the approximated integral with a discrete set of fictitious components is proposed. The fictitious component intensities are determined on an approximate way from the boundary condition. An approximate solution of the heat conduction problem is obtained by extension in time and contraction in space of the approximated integral.
Janusz Jankowski2008-01-28Z2013-01-22T08:43:13Zhttp://cab.unime.it/mus/id/eprint/459This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4592008-01-28ZThermodynamic and mesoscopic modeling of tumbling nematics, of shear-thickening fluids and of stick-slip-like flow behavior Shear thickening, i.e. the increase of the viscosity with increasing shear rate as it occurs in dense colloidal dispersions and polymeric fluids is an intriguing phenomenon with a considerable potential for technical applications. The theoretical description of this phenomenon is patterned after the thermodynamic and mesoscopic modeling of the orientational dynamics and the flow behavior of liquid crystals in the isotropic and nematic phases, where the theoretical basis is well-established. Even there the solutions of the relevant equations recently yielded surprises: not only stable flow alignment and a periodic behavior (tumbling) are found as response to an imposed stationary shear flow but also irregular and chaotic dynamics occurs for certain parameter ranges. To treat shear-thickening fluids, a non-linear Maxwell model equation for the symmetric traceless part of the stress tensor has been proposed in analogy to the equations obeyed by the alignment tensor of nematics. The fluid-solid transition is formally analogous to the isotropic-nematic transition. In addition to shear-thickening and shear-thinning fluids, substances with yield stress can be modeled. Furthermore, periodic stick-slip-like motions and also chaotic behavior are found. In the latter cases, the instantaneous entropy production is not always positive. Yet it is comforting that its long-time average is in accord with the second law.
Siegfried HessSebastian HeidenreichPatrick IlgChris GoddardOrtwin Hess2008-01-28Z2013-04-02T09:09:31Zhttp://cab.unime.it/mus/id/eprint/458This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4582008-01-28ZClose-to-Fourier heat conduction equation for solids: motivation and symbolic-numerical analysis Heat conduction close-to-Fourier means, that we look for a minimal extension of heat conduction theory using the usual Fourier expression of the heat flux density and modifying that of the internal energy as minimal as possible by choosing the minimal state space. Applying Liu's procedure results in the class of materials and a differential equation both belonging to the close-to-Fourier case of heat conduction. A symbolic-numerical computing method is applied to approximate the numerical solutions of 2 special heat conduction equations belonging to the close-to-Fourier class.
Heiko HerrmannHong GuGunnar RücknerJurgent SiebertWolfgang Muschik2007-10-09Z2010-04-13T11:17:11Zhttp://cab.unime.it/mus/id/eprint/444This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4442007-10-09ZOptical emission spectroscopy study of the expansion dynamics of a laser generated plasma during the deposition of thin films by laser ablation The dynamics of the expanding plasma produced by excimer laser ablation of different materials such as silicon, silicon carbide, graphite and tin powder were studied by means of time integrated, spatially resolved emission spectroscopy and fast photography imaging of the expanding plasma. Experiments were performed both in vacuum and in different pure background atmosphere (i.e. oxygen or nitrogen) and, finally, in gaseous mixtures (i.e. in O2/Ar and N2/Ar mixtures). These investigations were performed to gather information on the nature of the chemical species present in the plasma and on the occurrence of chemical reactions during the interaction between the plasma and the background gas. Then, we tried to correlate the plasma expansion dynamics to the structural and physical properties of the deposited materials. Experimental results clearly indicate that there is a strong correlation between the plasma expansion dynamics and the structural properties of the deposited thin films. In this respect, the investigations performed by means of fast photography and of optical emission spectroscopy revealed themselves as powerful tools for an efficient control of the deposition process itself.
Enza FazioFrancesco BarrecaBarbara FazioFortunato NeriSebastiano Trusso2007-10-05Z2010-04-13T11:17:08Zhttp://cab.unime.it/mus/id/eprint/441This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4412007-10-05ZL'impossibile ipotesi radiativa nella formazione della Shroud body image In this paper we studied the radiative hypothesis as the mechanism that acts at a distance in the Shroud body image formation. The comparison with the known characteristics of the above image shows good agreement for the resolution, penetration depth and I(z) correlation. This does not happen for the chemical modification in the region where the image lies. Hence, we reject the radiative hypothesis.
Giovanni FazioAntonella Roberto2007-04-16Z2010-04-13T11:17:46Zhttp://cab.unime.it/mus/id/eprint/427This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4272007-04-16ZMelting line of Krypton in extreme thermodynamic regimesWe have performed extensive computer simulations of the thermodynamic and structural properties of the krypton rare gas modeled by the modified Buckingham exponential-6 interatomic potential. Using a new set of potential parameters, we have found a good agreement with the room temperature equation of state at very high pressure obtained by diamond anvil cell experiments. Moreover, the melting line of the model has been estimated through the Lindemann criterion; the agreement with the low-pressure experiments is excellent, whereas at higher pressure, the model poorly reproduces the typical softening of the experimental melting curve.
Emanuela GiuffrèFranz Saija2007-04-16Z2010-04-13T11:17:35Zhttp://cab.unime.it/mus/id/eprint/428This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/4282007-04-16ZA possible mechanism underlying the anomalous dielectric response in concentrated methanol-in-carbon tetrachloride mixturesThe association of CCl4 with the non-donating ends of open (chain-like)methanol aggregates, is shown to be relevant in the occurrence of positive deviations of the static dielectric constant with respect to ideality in methanol/CCl4 mixtures. This interaction
tends to reduce in fact the fraction of methanol aggregated in cyclic clusters.
This hypothesis is suggested by the comparison with the data of lattice calculations for the equilibrium distribution of methanol clusters.Marco PierucciniFranz Saija2007-02-13Z2010-04-13T11:17:52Zhttp://cab.unime.it/mus/id/eprint/399This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3992007-02-13ZQuantum-Classical Dynamics of Wave FieldsAn approach to the quantum-classical mechanics of
phase space dependent operators, which has been proposed recently, is remodeled as a formalism for wave fields.
Such wave fields obey a system of coupled non-linear equations that can be written by means of a suitable non-Hamiltonian bracket.
As an example, the theory is applied to the relaxation dynamics of the spin-boson model.
In the adiabatic limit, a good agreement with calculations
performed by the operator approach is obtained.
Moreover, the theory proposed in this paper
can take nonadiabatic effects into account
without resorting to surface-hopping approximations.
Hence, the results obtained follow qualitatively those
of previous surface-hopping calculations
and increase by a factor of (at least) two the time length
over which nonadiabatic dynamics can be propagated
with small statistical errors.
Moreover, it is worth to note that the dynamics of
quantum-classical wave fields here proposed is a straightforward non-Hamiltonian generalization of the formalism for non-linear quantum mechanics that Weinberg introduced recently.Alessandro Sergiasergi@unime.it2006-05-12Z2010-04-13T11:17:55Zhttp://cab.unime.it/mus/id/eprint/392This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3922006-05-12ZQuantum-Classical Dynamics of Wave FieldsThe recent approach to the quantum-classical mechanics of
phase space dependent operators is recast
into a formalism for wave fields.
It turns out that such wave fields
obey a system of coupled non-linear equations where
each equation is not Hermitian. However,
backward and forward time-evolution
is combined in such a way as to conserve probability.
Notwithstanding their non-linear form, the equations of motion
for such phase space dependent wave fields can be
expressed by means of a suitable non-Hamiltonian bracket.
Thus, it can be realized that the non-Hamiltonian dynamics of
quantum-classical wave fields is a straightforward
generalization of the formalism for non-linear
quantum mechanics that Weinberg proposed recently.Alessandro Sergiasergi@unime.it2005-12-02Z2010-04-13T11:19:28Zhttp://cab.unime.it/mus/id/eprint/354This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3542005-12-02ZNon-Hamiltonian Quantum Mechanics.
Relation between operator and wave schemes of motionThe symplectic structure of Weinberg's formalism for nonlinear
quantum mechanics is first unveiled and then generalized
to introduce non-Hamiltonian quantum mechanics.
By exploiting the correspondence between wave
and matrix mechanics, a link between this generalization
and a non-Hamiltonian commutator, proposed recently by this author,
is found.
The general correspondence between operator and wave formalisms
in non-Hamiltonian quantum mechanics
is exploited to introduce a quantum-classical theory
of wave fields.
This can be considered as a first step toward a deeper
understanding of the relation between operator quantum-classical
mechanics, introduced some time ago, and the original
quantum-classical scheme of motion where
wave functions are evolved in time and
the classical degrees of freedom follows
surface-hopping trajectories on single quantum states.Alessandro Sergiasergi@unime.it2005-11-23Z2010-04-13T11:19:36Zhttp://cab.unime.it/mus/id/eprint/350This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3502005-11-23ZOn the Geometry of Non-Hamiltonian Phase SpaceIn this paper the statistical mechanics of canonical,
non-canonical and non-Hamiltonian systems is analyzed rigorously
by throwing light onto the peculiar geometric structure of phase
space. Misleading points, regarding generalized brackets and
Jacobi relations, are clarified. The accessory role of phase space
compressibility in the statistical mechanics of non-canonical and
non-Hamiltonian systems is also unveiled. A rigorous definition of
the (relative) entropy for continuous probability distributions is
adopted and used in order to introduce maximum entropy principles
for non-canonical and non-Hamiltonian systems. Although the
attention is concentrated on the geometry of phase space under
equilibrium thermodynamic conditions, the results and the points of view
presented lay the foundations for a maximum entropy approach to
non-Hamiltonian dissipative systems.Alessandro Sergiasergi@unime.it2005-11-23Z2010-04-13T11:19:39Zhttp://cab.unime.it/mus/id/eprint/351This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3512005-11-23ZStatistical Mechanics of Quantum-Classical Systems with Holonomic ConstraintsThe statistical mechanics of quantum-classical systems
with holonomic constraints
is formulated rigorously by unifying the classical Dirac bracket and the
quantum-classical bracket in matrix form.
The resulting Dirac quantum-classical
theory, which conserves the holonomic constraints exactly, is then used
to formulate time evolution and statistical mechanics.
The correct momentum-jump approximation for constrained system arises
naturally from this formalism.
Finally, in analogy with what was found in the classical case, it
is shown that the rigorous linear
response function of constrained quantum-classical systems
contains non-trivial additional terms which are absent
in the response of unconstrained systems.Alessandro Sergiasergi@unime.it2005-11-14Z2010-04-13T11:19:48Zhttp://cab.unime.it/mus/id/eprint/348This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3482005-11-14ZNon-Hamiltonian Commutators in Quantum MechanicsThe symplectic structure of quantum commutators is first unveiled and then exploited
to introduce generalized non-Hamiltonian brackets in quantum mechanics.
It is easily recognized that quantum-classical systems
are described by a particular realization of such a bracket.
In light of previous work, this introduces
a unified approach to classical and
quantum-classical non-Hamiltonian dynamics.
In order to illustrate the use
of non-Hamiltonian commutators, it is shown how to define
thermodynamic constraints in quantum-classical systems.
In particular, quantum-classical Nos\'e-Hoover equations of motion
and the associated stationary density matrix are derived.
The non-Hamiltonian commutators for both Nos\'e-Hoover chains
and Nos\'e-Andersen (constant-pressure constant temperature)
dynamics are also given.
Perspectives of the formalism are discussed.Alessandro Sergiasergi@unime.it2005-09-26Z2010-04-13T11:20:13Zhttp://cab.unime.it/mus/id/eprint/334This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3342005-09-26ZPhase space flows for non-Hamiltonian systems with constraintsIn this paper, non-Hamiltonian systems with holonomic constraints
are treated by a generalization of Dirac's formalism.
Non-Hamiltonian phase space flows can be described
by generalized antisymmetric brackets
or by general Liouville operators which cannot be derived
from brackets. Both situations are treated.
In the first case, a Nos\'e-Dirac
bracket is introduced as an example.
In the second one, Dirac's recipe for
projecting out constrained variables from time translation operators
is generalized and then applied to non-Hamiltonian linear response.
Dirac's formalism avoids spurious terms in the response function
of constrained systems. However, corrections coming from phase
space measure must be considered for general perturbations.Alessandro Sergi2005-06-01Z2012-09-20T08:44:12Zhttp://cab.unime.it/mus/id/eprint/324This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3242005-06-01ZOptical mapping of amplitude and phase of excitonic wave functions in a quantum dot systemWe propose a technique based on a near-field scanning optical microscope, able to measure the spatial variations of both amplitude and phase of the wave functions of the individual eigenstates of a quantum dot system. The proposed scheme is based on a near-field optical microscope working in collection mode combined with a Mach-Zehnder interferometer. We analyze the response function of this device and present microscopic numerical calculations simulating the measurements. These results show that spatially resolved spectroscopy can go beyond measurements of local density of states and open the way to an optical microscopy that, exploiting the coherence properties of light, is able to provide direct and complete quantum-mechanical information on the spatial variations of solid-state mesoscopic quantum eigenfunctions.Omar Di StefanoSalvatore SavastaGiuseppe PistoneGiovanna MartinoRaffaello Girlanda2005-05-31Z2010-04-13T11:20:36Zhttp://cab.unime.it/mus/id/eprint/319This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3192005-05-31ZHyper Raman Scattering in Microcavity Quantum Wells: A Quantum Optical Process in the Strong Coupling RegimeWe analyze the hyper Raman scattering process in a quantum well grown inside a semiconductor microcavity and present a microscopic calculation of emission spectra as a function of excitation energy, detuning, and angles. The exciton-photon coupling is treated non-perturbatively to include polariton effects and the Coulomb interaction between electrons is treated beyond the mean field approximation. The observation of hyper Raman scattering in semiconductor microcavities would represent an important step for the realization of non-classical optical states based on excitons. We find that the polaritons emitted in this scattering process are strongly correlated. This correlation,can be efficiently transferred to output photons, resulting in emission of two correlated non-classical light beams. As a probe of the quantum correlation we calculate the output spectrum of fluctuations in the intensity difference of the two beams generated in the hyper Raman process.Salvatore SavastaRaffaello GirlandaGiovanna Martino2005-05-31Z2010-04-13T11:20:24Zhttp://cab.unime.it/mus/id/eprint/320This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3202005-05-31ZLooking at Localized Excitons in Quantum Structures: A Theoretical DescriptionWe present a theory of scanning local optical spectroscopy in quantum structures taking into account structural disorder. The calculated spatially resolved spectra show the individual spectral lines from the exciton states localized by the disordered potential as well as the quasicontinua spectra at positions close to the potential barriers in agreement with the experimental findings.Omar Di StefanoSalvatore SavastaGiovanna MartinoRaffaello Girlanda2005-05-31Z2010-04-13T11:20:30Zhttp://cab.unime.it/mus/id/eprint/322This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3222005-05-31ZMany-Body and Correlation Effects on Parametric Polariton Amplification in Semiconductor MicrocavitiesThe complexity induced by the Coulomb interaction between electrons determines the noninstantaneous character of exciton-exciton collisions. We show that the exciton-photon coupling in semiconductor microcavities is able to alter the exciton dynamics during collisions strongly affecting the effective scattering rates. Our analysis clarifies the origin of the great enhancement of parametric gain observed when increasing the polariton splitting. It also demonstrates that exciton-exciton collisions in semiconductors can be controlled and engineered to produce almost decoherence-free collisions for the realization of all-optical microscopic devices.Salvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-31Z2012-09-20T08:43:49Zhttp://cab.unime.it/mus/id/eprint/323This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3232005-05-31ZMicroscopic theory of spatially resolved photoluminescence in quantum structuresWe present a microscopic quantum theory of spatially resolved photoluminescence in quantum wells with interface fluctuations. The theory can model low-temperature photoluminescence and photoluminescence excitation experiments performed in illumination, collection,illumination-collection mode or diffusion experiments where the spatial positions of excitation and collection are scanned independently. Numerically calculated two-dimensional images clarify the impact of the microscope setup on the obtained images and resolutions.Giuseppe PistoneSalvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-31Z2010-04-13T11:20:19Zhttp://cab.unime.it/mus/id/eprint/325This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3252005-05-31ZSpectroscopy of four-particle correlations in semiconductor microcavitiesWe present a theory of ultrafast time-resolved pump and probe spectroscopy in semiconductor microcavities. The numerical solutions are in excellent agreement with experimental data. An analytical study based on the Weisskopf-Wigner approximation gives physical insight into the transient optical nonlinearities of semiconductor microcavites. It is able to explain the physical origin of the unusual transient shifts and asymmetricexcitation-induced dephasing observed experimentally. this theory demonstrates that the nonperturbative regime provides a unique tool for measuring the spectrum of four-particle correlations.Salvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-31Z2010-04-13T11:20:20Zhttp://cab.unime.it/mus/id/eprint/326This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3262005-05-31ZTransiet optical stark shift and excitation induced dephasing in the non-perturbative regimeWe show that the exciton-exciton scattering continuum has a significant influence on the transient non-linear optical response of semiconductor microcavities. Comparison between transient shifts observed in pump and probe experiments and calculations demonstrates almost complete cancellation between mean-field and two-exciton continuum contributions. Moreover, we show that suppression of non-linear absorption of the lower polariton observed in many experiments is determined by the specific spectral shape of these correlations. In particular, we find that the pump induced dephasing of polariton resonances is proportional to the spectrum of four-particle correlations calculated at the energy sum of the pumped and probed polaritons.Salvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-31Z2010-04-13T11:20:22Zhttp://cab.unime.it/mus/id/eprint/327This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3272005-05-31ZThe effect of the exciton continuum on the exciton-exciton correlationWe present a numeric calculation of the exciton-exciton correlation for a one-dimensional semiconductor model with long-range Coulomb interactions, taking into account the effect of the effect of the exciton continuum. we use the obtained correlation functions to calculate the time integrated intensity of the four wave mixing signal. Changing the central frequency of the exciting pulses we observe changes in the profile and in the rise time of the time integrated signal for negative delays in qualitative agreement with experimental results. Our results show theoretically how the exciton continuum affects the coherence of four-particle correlations.Giovanna MartinoSalvatore SavastaRaffaello Girlanda2005-05-31Z2010-04-13T11:20:16Zhttp://cab.unime.it/mus/id/eprint/328This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3282005-05-31ZPropagation of nonclassical light through a semiconductor microcavityWe extend recently developed schemes for field quantization in absorbing dielectric media with local susceptibilities to dielectric systems described by a nonlocal susceptibility, in order to quantize the electromagnetic field in quantum wells embedded in planar semiconductor microcavities. As an application of the formalism, we analyze the effects of the propagation through a semiconductor microcavity on a continuous-mode squeezed coherent state. In particular, we calculate the varince of the field trasmitted through the microcavity in the case of strong coupling regime for different detection schemes, as a function of the detuning, the exciton-photon coupling and the exciton homogeneous broadeningOmar Di StefanoSalvatore SavastaRaffaello Girlanda2005-05-31Z2010-04-13T09:39:16Zhttp://cab.unime.it/mus/id/eprint/329This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3292005-05-31ZThe particle-photon interaction in systems descrided by model hamiltonians in second quantizationA simple replacement rule which allows the direct formulation in second quantization of the particle-photon interaction Hamiltonian in the velocity gauge is presented. We show that a transformation of the creation and annihilation operators of the particle Hamiltonian gives the interaction Hamiltonian. The rule is valid for both local and nonlocal Hamiltonian and gives the correct expression of the photon self-interaction term A2 also when only a projection of the particle Hamiltonian is taken into account. As an example the replacement rule is applied to the exciton operators in order to derive the polariton HamiltonianSalvatore SavastaRaffaello Girlanda2005-05-30Z2010-04-13T11:20:51Zhttp://cab.unime.it/mus/id/eprint/307This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3072005-05-30ZThe influence of four-particle correlations on the parametric polariton amplificationWe present a microscopic theory of parametric polariton amplification in semiconductor microcavities including the influence of exciton-exciton correlations beyond mean-field. The complexity induced by the Coulomb interaction between electrons determines the noninstantaneous character of exciton-exciton collisions. We find that the observed great enhancement of gain when increasing the polariton splitting origins from the unique interplay of the noninstantaneous nature of exciton-exciton interactions with the strong coupling regime giving rise to polaritons.
Salvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-30Z2010-04-13T11:20:55Zhttp://cab.unime.it/mus/id/eprint/309This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3092005-05-30ZImaging the wavefunctions of a quantum dot systemWe describe how, exploiting the current scanning near-field optical techniques, it is possible to map phase and modulus of the wavefunctions of a quantum dot system. In particular we propose an experimental setup based on an interferometric technique able to measure simultaneously modulus and phase of wavefunctions. We present numerical calculations simulating the measurements on dots arising from interface fluctuations of GaAs quantum wells.Omar Di StefanoSalvatore SavastaGiovanna MartinoRaffaello Girlanda2005-05-30Z2010-04-13T11:20:48Zhttp://cab.unime.it/mus/id/eprint/313This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3132005-05-30ZTheory of Transient Optical Nonlinearities in Semiconductor MicrocavitiesWe present a theory of ultrafast time-resolved nonlinear spectroscopy in semiconductor microcavitiesincluding the influence of many-body and correlation effects beyond mean-field calculations. The theory,in close agreement with a number of experimental results, shows that semiconductor microcavities provide aunique tool for measuring the spectrum of four-particle correlations. We apply the theory to analyze the polaritonparametric amplification in semiconductor microcavities. The obtained results demonstrate that exciton exciton collisions can be controlled and engineered to produce almost decoherence-free collisions for the realizationof completely optical microscopic devicesRaffaello GirlandaSalvatore Savasta2005-05-30Z2010-04-13T11:20:38Zhttp://cab.unime.it/mus/id/eprint/314This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3142005-05-30ZBiphotons from BiexcitonsWe analyze the spontaneous and stimulated optical decay of states with two electron-hole pairs virtually excited by optical pumping. We find that the photon pairs from the spontaneous fission in bulk large-gap semiconductors and in semiconductor microcavities exhibit quantum features which can be observed by coincidence detection.Salvatore SavastaGiovanna MartinoOmar Di StefanoRaffaello Girlanda2005-05-30Z2010-04-13T11:20:41Zhttp://cab.unime.it/mus/id/eprint/315This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3152005-05-30ZCoherence and correlation in semiconductor microcavitiesWe present an overview of our results concerning the influence of two-pair continuum coherences on the transient nonlinear optical response of semiconductor microcavities. We show that the interplay between these 4-particle coherences and the nonperturbative light-matter interaction produces highly desirable almost decoherence-free exciton-exciton collisions on the lower polariton branch. This effect gives rise to the very different nonlinear absorption rates on the two polariton branches observed in many experiments and make possible to reach a very high degree of amplification in samples with large Rabi splitting. Moreover, we show that the availability of almost decoherence free exciton-exciton collisions can be used for the realization of coherent trapping of polariton emission and amplification. This coherent manipulation and trapping of many-particle polariton states can be performed employing both ultrafast and continuous wave operation.Omar Di StefanoSalvatore SavastaRaffaello Girlanda2005-05-30Z2010-04-13T11:20:41Zhttp://cab.unime.it/mus/id/eprint/316This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3162005-05-30ZEntangled photon pairs from the optical decay of biexcitonsWe show that it is possible to transfer the exciton-exciton Coulomb correlation to photons, producing thus pairs of near-gap photons with a high degree of quantum entanglement. The photon pairs emerge from the spontaneous optical decay of biexcitons into two polaritons. The pair intensity-correlations, calculated in the low density limit for a CuCl slab, exhibit quantum features which can be observed by coincidence detection.Salvatore SavastaGiovanna MartinoRaffaello Girlanda2005-05-30Z2010-04-13T11:20:32Zhttp://cab.unime.it/mus/id/eprint/317This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3172005-05-30ZMicroscopic calculation of noise current operators for electromagnetic field quantization in absorbing material systems.We present a microscopic quantization scheme for the electromagnetic field in dispersive and lossy dieletrics of arbitrary geometry. This method also describes anisotropic media and media driven by ligth field via a spatially nonlocal permittivity. The method removes the need for complicated diagonalization of material, reservoir and field variables and allows us to include the effect of all the material excitations. Dissipation inside the medium is described by considering the coupling of the polarization quanta of the system with the reservoir oscillators in the usual Langevin approach. Omar Di StefanoSalvatore SavastaRaffaello Girlanda2005-05-30Z2012-09-20T08:44:38Zhttp://cab.unime.it/mus/id/eprint/318This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3182005-05-30ZSpatially resolved spectra in semiconductor quantum structures: spatially averaged spectra compared to far-field spectra. The optical spectra of homogeneous surface systems can display remarkable differences in the near and far zones. The spectral changes occur due to the loss of evanescent modes in the far zone. These changes clearly show that near-field optical spectroscopy, besides resolving nanometric structures give also access to excitations that cannot be revealed in the far zone. Are these spectral changes detectable in real systems affected by disorder and imperfections? We address this issue by presenting a theoretical analysis of the local optical properties of semiconductor quantum wells including the effects of interface fluctuations. In particular we compare the far-field absorption spectrum with spatially averaged absorption spectra calculaded at different spatial resolutions. We find that summing up local optical spectra does not reproduce the global spectrum in contrast to findings at diffraction-limited resolutions. Giuseppe PistoneSalvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-27Z2010-04-13T11:20:43Zhttp://cab.unime.it/mus/id/eprint/311This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3112005-05-27ZThree-dimensional quantum-optical input-output relations for arbitrary planar dielectricsWe present a three-dimensional quantum theory of light scattering, absorption, and emission in arbitrary planar dielectric systems. The theory is based on a scheme for quantization of the electromagnetic field in dispersive and lossy arbitrary planar dielectrics that takes explicitly into account the finite extent of the medium. We present general quantum-optical input-output relations of the output TE and TM photon operators to the corresponding input photon operators and to the reservoir noise operators. These three-dimensional input-output relations are uniquely determined by knowledge of the classical light modes of the planar dielectric structure. Salvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-27Z2010-04-13T11:20:46Zhttp://cab.unime.it/mus/id/eprint/312This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3122005-05-27ZSignatures of the electromagnetic field quantization in the nonlinear optical response of excitonsWe present a fully quantum mechanical theory for an interacting system of photonsand Coulomb correlated electrons and holes in a semiconductor, using a pertubation series in theexciting laser field. The theory provides microscopic descriptions of nonlinear optical processes insemiconductors related to the electromagnetic field quantization. As an application of the theorywe show that it is possible to transfer the exciton exciton Coulomb correlation to photons, thusproducing pairs of near-gap photons with a high degree of quantum entanglement. The photon pairsemerge from the spontaneous optical decay of biexcitons into two polaritons. The pair intensitycorrelations, calculated in the lowdensity limit for a CuCl slab and for semiconductor microcavities,exhibit quantum features which can be observed by coincidence detection.Salvatore SavastaRaffaello Girlanda2005-05-25Z2010-04-13T09:39:06Zhttp://cab.unime.it/mus/id/eprint/287This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/2872005-05-25ZExciton-exciton correlation in the ultrafast nonlinear optical response in the nonperturbative regimeThe ultrafast nonlinear optical response of semiconductor-microcavities (SMCs) in the nonperturbative regime is attracting growing interest for exploring fundamental light-matter interactions in many-particle quantum systems, as well as for the future implementations of ultrafast photonic devices. In spite of many investigations, the coherent dynamics of excitonic nonlinear-response in the nonperturbative regime has not been fully understood. Open questions are how strong exciton-cavity coupling affects exciton-exciton (X-X) interactions, and how in turn the X-X correlation influences the nonlinear response of SmCs. We investigate these open questions and show that the nonperturbative regime provides an unprecedented tool for investigating four-particle correlations.We start from the equations for the third order exciton polarization and cavity field describing quantum optical effects and coherent nonlinear optics in SMCs, perform the semiclassical factorization and include multiple scattering processes. Salvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-25Z2012-09-20T08:42:43Zhttp://cab.unime.it/mus/id/eprint/288This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/2882005-05-25ZNear-field light emission from nano- and micrometric complex structuresWe propose a general theoretical scheme for the investigation of light emitted from nano- and micrometric structures of arbitrary shape and composition. More specifically, the proposed fully three-dimensional approach allows to derive the light-intensity distributions around the emitting structures and their modifications in the presence of nearby scattering objects. Our analysis allows to better identify the nontrivial relationship between near-field images and fluorescent objects.Marco PierucciniSalvatore SavastaRaffaello GirlandaR.C. IottiF. Rossi2005-05-25Z2013-01-22T10:48:23Zhttp://cab.unime.it/mus/id/eprint/291This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/2912005-05-25ZSilicon-based organic-inorganic microcavity and its dispersion curve from angle-resolved photoluminescence We report an experimental study of a planar organic-inorganic microcavity consisting of a porous silicon distributed Bragg reflector, a single layer of acridina orange as active material and a top aluminum reflector. By tuning the cavity resonance energy around the maximum of the organic material photoluminescence, we found an intense emission and a spectral narrowing of the emission band to about 45 meV. The angle-resolved photoluminescence spectra enable us to determine the microcavity dispersion curve. The very good agreement with the theoretical dispersion provides a precise determination of the refractive index of the organic material.A. ArenaS. A. PatanèG. SaittaSalvatore SavastaRaffaello GirlandaR. Rinaldi2005-05-25Z2010-04-13T11:21:24Zhttp://cab.unime.it/mus/id/eprint/292This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/2922005-05-25ZImaging spectroscopy of quantum wells with interfacial fluctuations: A theoretical description We present a theoretical approach for the simulation of scanning local optical spectroscopy in disordered quantum wells (QWs). After a single realization of the disorder potential, we calculate spectra on a mesh of points on the QW plane, thus obtaining a three-dimensional matrix of data from which we construct two-dimensional spectroscopic images of excitons laterally localized at interface fluctuations. Our simulations are in close agreement with the experimental findings, and contribute to the interpretation of spatially resolved spectra in QWs.Omar Di StefanoSalvatore SavastaGiovanna MartinoRaffaello Girlanda2005-05-25Z2012-09-20T08:43:38Zhttp://cab.unime.it/mus/id/eprint/293This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/2932005-05-25ZMicroscopic quantum theory of spatially resolved photoluminescence in semiconductor quantum structuresWe present a microscopic analysis of spatially resolved photoluminescence and photoluminescence excitation spectroscopy in semiconductor quantum structures. Such theoretical and numerical framework provides a general basis for the description of spectroscopic imaging in which the excitation and detection energies and spatial positions can all independently be scanned. The numerical results clarify the impact of the near-field optical setup on the obtained images and resolutions.Giuseppe PistoneSalvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-25Z2013-01-22T10:47:57Zhttp://cab.unime.it/mus/id/eprint/294This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/2942005-05-25ZPhotoluminescence from a soluble semiconducting polymer in waveguide and microcavity configurationsThe optical properties of thin films of PVK-Alq3 are examined by means of spectrophotometry in the UV-VIS-NIR. Photoluminescence (PL) measurements indicate that the polymer films deposited on glass substrates behave as asymmetrical planar waveguides for the emitted light. The waveguided luminescence shrinks and change color with respect to the non-waveguided emission. Stronger changes in the luminescence features are observed using a microcavity configuration, obtained by spin-coating PVK-Alq3 on an inorganic Distributed Bragg Reflector (DBR) and by vacuum-depositing a thick aluminum layer on the top of the polymer film. M. AllegriniA. ArenaM. LabardiGiovanna MartinoRaffaello GirlandaC. PaceS. A. PatanèG. SaittaSalvatore Savasta2005-05-25Z2010-04-13T11:21:17Zhttp://cab.unime.it/mus/id/eprint/297This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/2972005-05-25ZLight quantization for arbitrary scattering systemsWe present a quantum theory of light scattering for the analysis of the quantum statistical and fluctuation properties of light scattered or emitted by micrometric and nanometric three-dimensional structures of arbitrary shape. We obtain general three-dimensional quantum-optical input-output relations providing the output photon operators in terms of the input photon operators and of the noise currents of the scattering system. These relations hold also for photon operators associated with evanescent fields, for anisotropic scattering systems and/or for media with a nonlocal susceptibility. We find that the commutation relations of the output photon operators, carrying all the information on the scattering and/or the emission process, result to be fixed by energy conservation and reciprocity. We prove that this quantization scheme is consistent with QED commutation rules by using a novel relationship between vacuum and thermal fluctuations. This theoretical framework has been applied to analyze the spectral density of light close to a point scatterer under different nonequilibrium conditionsSalvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-25Z2010-04-13T11:21:09Zhttp://cab.unime.it/mus/id/eprint/298This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/2982005-05-25ZTheory of local optical spectroscopy of quantum wires with interface fluctuationsWe present a theory of local optical spectroscopy in quantum wires taking into account structural disorder. The calculated spatially resolved spectra show the individual spectral lines due to the exciton states localized by the disordered potential in agreement with experimental findings.We investigate systematically the influence of the potential profile and of the spatial resolution on the local optical spectra. Several line scans along the wire axis are obtained for different spatial correlations and strength of the disorder potential and for different spatial resolutions ranging from the subwavelength to the diffraction limit. Lowering the spatial resolution causes the disappearance of many spectral lines due to destructive spatial interference. However, our results show that information on the individual eigenstates of this quasi one-dimensional quantum system can be obtained at also resolutions significantly lower than the correlation length of interface fluctuations. Omar Di StefanoSalvatore SavastaRaffaello Girlanda2005-05-25Z2010-04-13T11:21:10Zhttp://cab.unime.it/mus/id/eprint/300This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3002005-05-25ZQuantum theory of light scattering for arbitrary finite size dieletric and conducting structuresWe present a quantum theory of ligth scattering for the analysis of the quantum statistical and fluctuation properties of light scattered or emitted by micrometric and nanometric three dimensional structures of arbitrary shape. This theory provides a general and unified basis for analysing a large class of optical processe where quantum and or thermal fluctuations play a role. Salvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-25Z2010-04-13T11:21:12Zhttp://cab.unime.it/mus/id/eprint/301This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3012005-05-25ZThe influence of two-exciton correlations on the dynamics of parametric polariton amplificationWe present an overview of our results concerning the influence of two-pair continuum coherences onthe transient nonlinear optical response of semiconductor microcavities. We show that the interplaybetween these 4-particle coherences and the nonperturbative light-matter interaction produces highlydesirable almost decoherence-free exciton-exciton collisions on the lower polariton branch. This effectgives rise to the very different nonlinear absorption rates on the two polariton branches observed inmany experiments and make possible to reach a very-high degree of amplification in samples withlarge Rabi splitting.Omar Di StefanoSalvatore SavastaRaffaello Girlanda2005-05-25Z2012-09-20T08:44:00Zhttp://cab.unime.it/mus/id/eprint/302This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3022005-05-25ZSpatially resolved photoluminescence in semiconductor nanostructures: A theoretical descriptionWe present a microscopic quantum theory of spatially resolved photoluminescence in quantum wells with interface fluctuations that includes light quantization, acustic phonon scattering, and inhomogeneous sample-excitation and/or light-detection. The theory can model low-temperature photoluminescence and photoluminescence excitation experiments performed in illumination, collection or illumination-collection mode or diffusion experiments where the spatial positions of excitation and collection are scanned independently. Numerically calculated two-dimensional images agree with images from near-field photoluminescence experiments and put forward the potentials of the method for the understanding of near-field light emission from semiconductor quantum structures.Giuseppe PistoneSalvatore SavastaOmar Di StefanoRaffaello Girlanda2005-05-25Z2012-09-20T08:44:24Zhttp://cab.unime.it/mus/id/eprint/303This item is in the repository with the URL: http://cab.unime.it/mus/id/eprint/3032005-05-25ZIs the spatially averaged spectrum equal to the global spectrum?Near-field optical spectroscopy and microscopy give access to excitations that cannot be revealed in the far zone. In order to investigate these remarkable differences, we present a theoretical analysis of the local optical properties of semiconductor quantum wells including the effects of disorder arising from interface fluctuations. The far-field absorption spectrum is compared with spatially averaged absorption spectra calculated at different spatial resolutions. We find that summing up local optical spectra does not reproduce the global spectrum in contrast to findings at diffraction-limited resolutions.Giuseppe PistoneOmar Di StefanoSalvatore SavastaRaffaello Girlanda