Dissipative Continuous Spontaneous Localization (CSL) model

Collapse models explain the absence of quantum superpositions at the macroscopic scale, while giving practically the same predictions as quantum mechanics for microscopic systems. The Continuous Spontaneous Localization (CSL) model is the most refined and studied among collapse models. A well-known problem of this model, and of similar ones, is the steady and unlimited increase of the energy induced by the collapse noise. Here we present the dissipative version of the CSL model, which guarantees a finite energy during the entire system's evolution, thus making a crucial step toward a realistic energy-conserving collapse model. This is achieved by introducing a non-linear stochastic modification of the Schr\"odinger equation, which represents the action of a dissipative finite-temperature collapse noise. The possibility to introduce dissipation within collapse models in a consistent way will have relevant impact on the experimental investigations of the CSL model, and therefore also on the testability of the quantum superposition principle.Comment: 11 pages, 1 figure; v2 title changed, closer to published versio

Dissipative extension of the Ghirardi-Rimini-Weber model

In this paper we present an extension of the Ghirardi-Rimini-Weber model for the spontaneous collapse of the wavefunction. Through the inclusion of dissipation, we avoid the divergence of the energy on the long time scale, which affects the original model. In particular, we define new jump operators, which depend on the momentum of the system and lead to an exponential relaxation of the energy to a finite value. The finite asymptotic energy is naturally associated to a collapse noise with a finite temperature, which is a basic realistic feature of our extended model. Remarkably, even in the presence of a low temperature noise, the collapse model is effective. The action of the new jump operators still localizes the wavefunction and the relevance of the localization increases with the size of the system, according to the so-called amplification mechanism, which guarantees a unified description of the evolution of microscopic and macroscopic systems. We study in detail the features of our model, both at the level of the trajectories in the Hilbert space and at the level of the master equation for the average state of the system. In addition, we show that the dissipative Ghirardi-Rimini-Weber model, as well as the original one, can be fully characterized in a compact way by means of a proper stochastic differential equation.Comment: 25 pages, 2 figures; v2: close to the published versio

Gravity and the Collapse of the Wave Function: a Probe into Di\'osi-Penrose model

We investigate the Di\'osi-Penrose (DP) proposal for connecting the collapse of the wave function to gravity. The DP model needs a free parameter, acting as a cut-off to regularize the dynamics, and the predictions of the model highly depend on the value of this cut-off. The Compton wavelength of a nucleon seems to be the most reasonable cut-off value since it justifies the non-relativistic approach. However, with this value, the DP model predicts an unrealistic high rate of energy increase. Thus, one either is forced to choose a much larger cut-off, which is not physically justified and totally arbitrary, or one needs to include dissipative effects in order to tame the energy increase. Taking the analogy with dissipative collisional decoherence seriously, we develop a dissipative generalization of the DP model. We show that even with dissipative effects, the DP model contradicts known physical facts, unless either the cut-off is kept artificially large, or one limits the applicability of the model to massive systems. We also provide an estimation for the mass range of this applicability.Comment: 15 pages, 1 figure; v2 updated references and fixed minor mistakes in Eqs.(18) and (31)-(34), thanks to Marko Toros for pointing them ou

Bounds on collapse models from cold-atom experiments

The spontaneous localization mechanism of collapse models induces a Brownian motion in all physical systems. This effect is very weak, but experimental progress in creating ultracold atomic systems can be used to detect it. In this paper, we considered a recent experiment [1], where an atomic ensemble was cooled down to picokelvins. Any Brownian motion induces an extra increase of the position variance of the gas. We study this effect by solving the dynamical equations for the Continuous Spontaneous Localizations (CSL) model, as well as for its non-Markovian and dissipative extensions. The resulting bounds, with a 95% of confidence level, are beaten only by measurements of spontaneous X-ray emission and by experiments with cantilever (in the latter case, only for rC > 10^(-7) m, where rC is one of the two collapse parameters of the CSL model). We show that, contrary to the bounds given by X-ray measurements, non-Markovian effects do not change the bounds, for any reasonable choice of a frequency cutoff in the spectrum of the collapse noise. Therefore the bounds here considered are more robust. We also show that dissipative effects are unimportant for a large spectrum of temperatures of the noise, while for low temperatures the excluded region in the parameter space is the more reduced, the lower the temperature.Comment: 16 pages, 14 figure

Come diventare grandi rimanendo piccoli. Strategie di networking della Cooperazione Sociale ravennate

In numerosi paesi dell'Unione Europea, in questi ultimi anni, si assiste ad un processo di ridisegno (riforma) dei sistemi di welfare improntato da linee politiche che incentivano il passaggio da sistemi di finanziamento orientati al sostegno dell'offerta (gare di appalto, convenzionamento, ecc.) a sistemi volti al sostegno della domanda (buoni servizio, vouchers, accreditamento). All'interno di questi sistemi integrati di erogazione delle prestazioni (sanita', formazione professionale, servizi sociali, servizi educativi, ecc.) il ruolo assunto o assegnato alle organizzazioni di terzo settore, in qualita' di fornitori dei servizi di caring, varia grandemente da una funzione "ancillare", ad una "complementare" ad una "sussidiaria" (Bassi, Colozzi, 2003). I processi di riforma dei sistemi di welfare locale avranno un forte impatto sul ruolo e funzione dei soggetti nonprofit e in particolare stimoleranno la diffusione di quel sottoinsieme di essi maggiormente coinvolti nella erogazione dei servizi, le cosiddette imprese sociali (Defourny J. Nyssens M., 2007). Il presente articolo analizza la rete delle cooperative sociali attive nella Provincia di Ravenna e in particolare affronta la tematica delle "strategie di networking" (Wei-Skillern J., Marciano S., 2008; Wei-Skillern J., Battle Anderson B., 2003) da esse sperimentate, al fine di fronteggiare le sfide crescenti che il "mercato" dei servizi sociali locali, caratterizzato da una sempre maggiore competizione, pone loro. La cooperazione sociale ravennate pare aver individuato nel "Consorzio"(Carbognin M., 1999) la figura societaria e lo strumento operativo piu adeguato per usufruire dei benefici derivanti dalle "economie di scala" mantenendo una struttura reticolare di base costituita da una pluralita' di imprese di dimensioni piccole o medio-piccole.cooperazione sociale; welfare locale; strategie di networking

X-ray and light scattering from nanostructured thin films

The object of this thesis is the study of nanostructured thin films using inelastic fight scattering and elastic x-ray scattering techniques. Their use in combination with other techniques is a powerful tool for the investigation of nanostructured materials. X-ray, Raman and Brillouin characterisation of cluster-assembled carbon films, promising for applications in the field of catalysis, hydrogen storage and field emission, is here presented. X-ray reflectivity (XRR) provided a measure of the density. Raman spectroscopy showed that the local bonding in these amorphous films depends on the size distribution of the clusters and that it is possible to select the cluster size in order to grow films with tailored properties. Brillouin scattering provided a characterisation at the mesoscopic scale and an estimate of the elastic constants, revealing a very soft material. XRR was employed to study density, layering and roughness of a wide range of amorphous carbon films grown with different techniques. Some films possess an internal layering due to plasma instabilities in the deposition apparatus. By comparing XRR with Electron Energy Loss Spectroscopy, a unique value for the electron "effective mass" was deduced and a general relationship between sp(^3)-content and density was found. XRR and H effusion were used to determine the hydrogen content. A study of the size-dependent melting temperature in tin nanoparticle thin films was undertaken with a combined use of X-Ray Diffraction (XRD) and light scattering. A redshift in the position of a Rayleigh peak in the temperature-dependent Brillouin measurements was shown to be related to the melting of the nanoparticles and explained by an effective medium model. XRD also provided information on the low-level of stress in the particles. Low-frequency Raman scattering was used to study the behaviour of the acoustic modes of a single particle as a function of temperature

Social Innovation Policies with the Involvement of Social Economy Organizations. Survey Evidence from European Countries.

In this paper, we investigate significant social innovation policies (related to the concept of social investment) involving the role of Social Economy organizations, and we discuss some relevant national and regional social innovation experiences by relying upon the current national and international literature, reports and website information. The Working Paper is organized as follows. Section 1 is dedicated to briefly analyze the term “Social Innovation”. In Section 2, we investigate significant social innovation experiences involving the role of Social Economy organizations. We will carry out this analysis by reporting and rephrasing the answers to Question Q6 of the Template as given by the Academic Partners of the Innosi Project and to some email correspondence; and, whenever possible, by further analyzing in greater details some national social innovation experiences by relying upon the current national and international literature, reports and website information. In Section 3 we advance some concluding remarks

Modeling the Hydropower–Food Nexus in Large River Basins: A Mekong Case Study

An increasing global population and growing wealth are raising demand for energy and food, impacting on the environment and people living in river basins. Sectoral decision-making may not optimize socio-economic benefits because of perverse impacts in other sectors for people and ecosystems. The hydropower–food supply nexus in the Mekong River basins is assessed here in an influence model. This shows how altering one variable has consequent effects throughout the basin system. Options for strategic interventions to maximize benefits while minimizing negative impacts are identified that would enable national and sub-national policy makers to take more informed decisions across the hydropower, water and food supply sectors. This approach should be further tested to see if it may aid policy making in other large river systems around the world.The authors’ research was supported by the Luc Hoffmann Institute for conservation research through its Navigating the Nexus program