There is a rising concern about energy and environment for future. Transition from current fossil fuels to green fuels and building of cleaner environment to lead sustainable life is at enormous task. Hydrogen gas is recognized as a clean fuel and may be a sustainable solution. Hydrogen can be directly used as clean fuel in fuel cells with no harmful by-products. Chemical hydrides with high hydrogen storage capacity in terms of gravimetric and volumetric efficiencies are the most promising candidates to supply pure hydrogen at room temperature. Among them, Ammonia Borane (NH3BH3, AB) and Sodium borohydride (NaBH4, SBH) have drawn a lot of interest as they are stable, non-flammable, and nontoxic. Large amount of pure hydrogen gas is released during the hydrolysis of these hydrides in presence of certain catalysts and the by-products are non-toxic, environmentally safe and can be recycled. Co based catalysts are considered as good candidates for catalyzed hydrolysis owing to their good catalytic activity, low cost and effortless synthesis. In favor of environmental concern, especially the air pollution (conversion of CO to CO2) and water pollutions (organic pollutants) are vital problems and there is a serious need to mitigate these problems. Cobalt (Co) based materials are with high catalytic activity for hydrolysis, organic pollutants degradation and CO oxidation. So, a single Co based catalysts as powders and as immobilized coatings prepared by chemical reduction method and pulsed laser deposition (PLD) were studied for hydrogen production by hydrolysis of AB and SBH and thin film coatings Co3O4 were studied for CO oxidation and organic pollutants degradation. On the basis of characterization results, the role of catalyst to enhance catalytic activity is discussed in hydrolysis, CO oxidation and pollutants degradation reactions. The stability and re-usability of these catalysts have also been investigated.

Catalysts are of great importance in many different fields, including the energy and the environmental sectors. It is important to produce them with simple preparation technique and to enhance the catalysts surface-to-volume ratio. The work undertaken in this thesis concerns the synthesis of nanostructures by Pulsed Laser Deposition (PLD) and R.F. sputtering deposition and the tailoring of their structures by varying deposition parameters. We synthesized Cobalt oxide nanoparticles (NPs) by PLD and studied the influence of the deposition parameters (i.e. substrate temperature, target-to-substrate distance and partial pressure of Oxygen in the chamber) on the final structure and crystalline phase of the NPs. The deposited NPs can be divided in two main categories: small NPs having a diameter of about 5 nm, and big NPs of size ranging from 50 to 400 nm. Depending on the value chosen for the deposition parameters, small NPs have CoO- or Co3O4 crystalline phase, and NPs can have a core/shell structure. The phase composition of the core and of the shell also vary according to the deposition conditions. We synthesized thin film of Co-B NPs by PLD. Depending on the energy density, the laser process is able to produce well-dispersed spherical Co NPs partially embedded within B-based film matrix in a single-step deposition. The small size, the polycrystalline nature of Co NPs, and the presence of Boron matrix is important for catalytic performance of the Co-B film. The catalytic activity of the Co-B has been tested in hydrolysis of chemical hydrides (ammonia borane and sodium borohydride). PLD deposition of C-film, to serve as support for Co-B NPs, was performed at different Ar pressures (from 10 to 50 Pa) to tailor film roughness in order to investigate the role of porous and irregular C- surface on supporting Co-B NPs acting as catalysts. The measured hydrogen generation rate attained with C-supported Co-B catalyst film is higher than both unsupported-Co-B film and conventional Co-B powder. Multilayer ITO/Cr-doped-TiO2 thin films have been synthesized by radiofrequency magnetron sputtering in order to sensitize TiO2 in visible light and to lower the charge recombination rate in the Cr-doped-TiO2. When the multilayer films were exposed to visible light, we observed that the photocurrent increases as function of the number of bilayers by reaching the maximum with 6-bilayers of ITO/Cr-doped- TiO2. The superior photocatalytic efficiency of the 6-bilayers film implies higher hydrogen production rate through water-splitting. Spontaneous growth of Lead nanowires (NWs) have been observed in composite Al-Pb film deposited by R.F. sputtering deposition. The parameters of deposition and the storage of the Al-Pb films after deposition has been changed in order to understand the growth process of NWs. Evolution of NWs growth was also observed inside a SEM chamber. We propose that a stress-driven mechanism and the corrosion occurring on the films surface in environment atmosphere are the cause of NWs growth.

My PhD thesis is focused on geometric Hamiltonian formulation of Quanum Mechanics and its interplay with standard formulation. The main result is the construction of a general prescription to set up a quantum theory as a classical-like theory where quantum dynamics is given by a Hamiltonian vector field on a complex projective space with Kähler structure. In such geometric framework quantum states are represented by classical-like Liouville densities. After a complete characterization of classical-like observables in a finite-dimensional quantum theory, the observable C*-algebra is described in geometric Hamiltonian terms. In the final part of the work, the classical-like Hamiltonian formulation is applied to the study of composite quantum systems providing a notion of entanglement measure.

A century after the prediction of the existence of gravitational waves by A. Einstein and after over fifty years of experimental efforts, gravitational waves have been detected at Earth directly. This result is a major achievement and opens new prospectives for the exploration of our universe. Gravitational waves carry different and complementary information about the source with respect to electromagnetic signals. In particular the first detection demonstrated the existence of stellar-mass black holes, binary systems of black holes and their coalescence. The detection was made by the LIGO instruments which are twin kilometer-scale Michelson interferometers in the US. These detectors represent the second generation of gravitational wave interferometers and, for the first time, they achieved the outstanding strain sensitivity of 10^(-23) Hz^(-1/2) between 90Hz and 400Hz. In the next months the LIGO network will be joined by another second generation detector: Advanced Virgo located near Pisa, Italy. The sensitivity of these advanced detectors is set by different noise sources. In particular, in the low frequency range (below 100Hz) major contributions come from thermal noises, gravity gradient noise and radiation pressure noise; instead, the high frequency band (above 100-200Hz) is dominated by shot noise. Quantum noise (radiation pressure and shot noise) is expected to dominate the detector sensitivity in the whole frequency band at the final target laser input power. To decrease the shot noise while increasing the radiation-pressure noise, or vice-versa, Caves \cite{Caves1981} proposed in 1981 the idea of the squeezed-state technique. The LIGO collaboration demonstrated for the first time in 2011 that the injection of a squeezed vacuum state into the dark port of the interferometer can reduce the shot noise due to the quantum nature of light. This result was achieved with the German-British interferometer GEO600 and was replicated in 2013 with the LIGO interferometer at Livingston. After these results, the LIGO collaboration have pursued further the research in the squeezed-state technique which is considered mandatory for third generation of ground based interferometric detectors. In 2013, the Virgo collaboration started developing the squeezed-state technique. The subject of my thesis is the realization of a prototype of frequency independent squeezed vacuum state source to be injected in Advanced Virgo. This prototype is developed in collaboration with other Virgo groups.

In this work we have proposed a PSi based flow through bio-sensor able to perform fast and sensitive real time analysis. The present work is summarized as: 1. We have presented a simple fabrication method for n-type PSi free-standing membranes with straight and smooth pores of up to ~100nm of diameter. 2. A two solution method is presented to fabricate free standing porous membranes. 3. Our process maintains a very good planarity of the interface as demonstrated by the fabrication of very thin and large area free standing membranes. No HF concentration gradient effect is noticed. 4. We found that membranes detachment does not require a high current burst but it is a self-limited process that involves a thin transitional layer at the bottom of the porous region. 5. Covalent functionalization of silicon surface is found to be suitable used to stabilize the porous surface and to act as intermediate layer for binding of other bio-molecules. 6. Role of non-specific binding in sensing efficiency is analyzed by comparing flow over and flow-through sensing for sensor fabricated on silicon substrate and sensor in freestanding nature. 7. Real time sensitivity per unit length of 0.0053degree/NaCl% and 0.0148degree/NaCl% was observed respectively for porous alumina and PSi membranes and PSi was found more suitable and sensitive for bio-sensing applications.

In the past several years there has been a growing commercial interest in Concentration PhotoVoltaics (CPV) thanks to its promise of low cost electrical power generation. While the technology of CPV using point-focus Fresnel-like optical elements is reaching maturity, the systems based on dense array receivers still need further scientific progress. This thesis explores the field of CPV applied to a parabolic concentrator prototype and to a dense array receiver made of multijunction solar cells. The solar concentrator, completely designed and built at the University of Trento, is characterized, in order to get the illumination distribution on the PV receiver. The non-uniformity in incident flux results in a current mismatch among cells and strongly impacts the system performance. In order to solve this issue, we have proposed a new type of electrical connection by fitting each cell of the array with an individual DC-DC converter. This method is shown to increase the power transfer efficiency with respect to classical series connection, at least for the tested illumination levels and unbalances. The other main problem with dense array systems is the reliability of the PV receiver, with special attention to the high thermal flux to be dissipated. Several types of water-cooled receivers have been built, with different material configurations that were previously studied with 3D thermal modeling. In particular the building of a multi-cell receiver has required the design of the insulation/interconnection between the cells, the tuning of the cell soldering and the realization of front contact connections.

A relevant contribution in the explosion of the silicon photonics derives from its nonlinear optics branch, also called nonlinear silicon photonics. This research area exploits the tight confinement of the light, which is allowed by the high contrast index in the silicon sub-micron-structures, and the nonlinearity of silicon to produce (fabricate, develop) novel active devices on the chip scale. Despite of the plenty of third order nonlinear optical phenomena, silicon lacks the second order nonlinearity, which is an essential component of nonlinear optics. In fact, due to the inversion symmetry of its crystalline structure, silicon is characterized by a zero bulk second order nonlinear susceptibility in electric-dipole approximation. Hence, this thesis had the general goal to demonstrate the possibility to perform an all optical experiment of frequency conversion by making use of the second order nonlinear response induced in strained silicon waveguides. The necessary condition to have a bulk second order nonlinear response in silicon is the breaking of its centrosymmetry. This can be obtained by deforming the crystalline structure, for example, by means of a mechanical strain. Based on this approach, this thesis presents and discusses the results achieved in the characterization of the mechanical properties and the strain-induced second order nonlinearity of silicon-on-insulator (SOI) waveguides mechanically strained by using a stressing cladding layer deposited on the waveguide. In particular, the mechanical characterization has been performed by micro-Raman spectroscopy allowing to reconstruct for the first time the two dimensional spatial distribution of the strain across the waveguide cross-section and study its inhomogeneity by varying the stress applied by the cladding overlayer. The second order nonlinear response and the influence of the strain field on it have been experimentally investigated through Second Harmonic Generation (SHG) experiments in transmission configuration and theoretically analyzed, pointing out the strict dependence of the second order nonlinear susceptibility on the extent and inhomogeneity of the strain field.

LISA is the proposed ESA-NASA space-based gravitational wave detector in the 0.1 mHz - 0.1 Hz band. LISA Pathfinder is the down-scaled version of a single LISA arm. In this thesis it is shown that the arm -- named Doppler link -- can be treated as a differential accelerometer, measuring the relative acceleration between test masses. LISA Pathfinder -- the in-flight test of the LISA instrumentation -- is currently in the final implementation and planned to be launched in 2014. It will set stringent constraints, with unprecedented pureness, on the ability to put test masses in geodesic motion to within the required differential acceleration of 3\times10^{-14} m s^{-2} Hz^{-1/2} and track their relative motion to within the required differential displacement measurement noise of 9\times10^{-12} m Hz^{-1/2}, at frequencies relevant for the detection of gravitational waves. Given the scientific objectives, it will carry out -- for the first time with such high accuracy required for gravitational wave detection -- the science of spacetime metrology, in which the Doppler link between two free-falling test masses measures the spacetime curvature. This thesis contains a novel approach to the calculation of the Doppler response to gravitational waves. It shows that the parallel transport of 4-vectors records the history of gravitational wave signals passing through photons exchanged between an emitter and a receiver. In practice, the Doppler link is implemented with 4 bodies (two test masses and two spacecrafts) in LISA and 3 bodies (two test masses within a spacecraft) in LISA Pathfinder. Different non-idealities may originate in the measurement process and noise sources couple the motion of the test masses with that of the spacecraft. To compensate for such disturbances and stabilize the system a control logic is implemented during the measurement. The complex closed-loop dynamics of LISA Pathfinder can be condensed into operators acting on the physical coordinates describing the relative motion. The formalism can handle the couplings between the test masses and the spacecraft, the sensing noise, as well as the cross-talk, and allows for the system calibration. It suppresses the transients in the estimated residual acceleration noise between the test masses. The scope of system identification is indeed the calibration of the instrument and the compensation of different effects. After introducing a model for LISA Pathfinder along the optical axis and an example of cross-talk from other degrees of freedom to the optical axis, this thesis describes some data analysis procedures applied to synthetic experiments and tested on a realistic simulator provided by ESA. The same procedures will also be adopted during the mission. Those identification experiments can also be optimized to get an improvement in precision of the noise parameters that the performances of the mission depend on. This thesis demonstrates the fundamental relevance of system identification for the success of LISA Pathfinder in demonstrating the principles of spacetime metrology needed for all future space-based missions.

No description available.

This thesis work covers both classical and quantum aspects of nonlinear propagation of photons in nanophotonic Silicon waveguides. The work has been carried out within the framework of the project SIQURO, which aims to bring the quantum world into integrated photonics by using the Silicon platform and, therefore, permitting in a natural way the integration of quantum photonics with electronics. The research towards on chip bright quantum sources of photon pairs has been done by investigating Multi Modal Four Wave Mixing in micrometer-size waveguides, thus exploiting the large third order nonlinearity of Silicon. The possibility to induce second order nonlinearities by straining its unit cell has been also analyzed through the study of the electro-optic effect. This has been done with the aim to promote Silicon as a platform for the integration of quantum sources of entangled photons based on Spontaneous Parametric Down Conversion. New quantum interference effects have been reported in a free space unbalanced Mach Zehnder interferometer asymmetrically excited by colour entangled photon pairs. Innovative designs of integrated quantum circuits have been proposed, which extend the capabilities of the quantum circuits demonstrated so far and provide additional functionalities. This work represents a step forward to the realization of self subsistent integrated devices for quantum enhanced measurement, quantum computation and quantum crypthography.