Random laser from engineered nanostructures obtained by surface tension driven lithography

The random laser emission from the functionalized thienyl-S,S-dioxide quinquethiophene (T5OCx) in confined patterns with different shapes is demonstrated. Functional patterning of the light emitter organic material in well defined features is obtained by spontaneous molecular self-assembly guided by surface tension driven (STD) lithography. Such controlled supramolecular nano-aggregates act as scattering centers allowing the fabrication of one-component organic lasers with no external resonator and with desired shape and efficiency. Atomic force microscopy shows that different geometric pattern with different supramolecular organization obtained by the lithographic process tailors the coherent emission properties by controlling the distribution and the size of the random scatterers

Experimental evidence of replica symmetry breaking in random lasers

Spin-glass theory is one of the leading paradigms of complex physics and describes condensed matter, neural networks and biological systems, ultracold atoms, random photonics, and many other research fields. According to this theory, identical systems under identical conditions may reach different states and provide different values for observable quantities. This effect is known as Replica Symmetry Breaking and is revealed by the shape of the probability distribution function of an order parameter named the Parisi overlap. However, a direct experimental evidence in any field of research is still missing. Here we investigate pulse-to-pulse fluctuations in random lasers, we introduce and measure the analogue of the Parisi overlap in independent experimental realizations of the same disordered sample, and we find that the distribution function yields evidence of a transition to a glassy light phase compatible with a replica symmetry breaking.Comment: 10 pages, 5 figure

Influence of high level requirements in aircraft design: From scratch to sketch

This paper suggests an innovative sketch procedure, especially envisaged for very complex and innovative transportation systems. In order to face with the increasing complexity and innovation levels, reducing development schedule and budget, a rational approach is developed and presented. At first, high level requirements, coming from different sources are elicited and then, through a detailed impact analysis, each design parameter used to sketch the vehicle layout is connected to one or more of these requirements. Then, different semi-empirical models, exploiting available statistical data, regulations and best practices, are developed and proper sizing algorithms are suggested to provide a quantitative base to the qualitative sketching procedure. In this approach, special attention is devoted to the evaluation of the impact of the integration of main subsystems (for example, propulsion, propellant, landing gear subsystems) into the final vehicle layout. Eventually, results of the application of the described procedure to an innovative hypersonic transportation system is reported, highlighting the benefit of the increased traceability of requirements into the final product

High level requirements impact on configuration trade-off analyses in a multidisciplinary integrated conceptual design methodology

This paper aims at suggesting rational algorithms for the selection of general characteristics of trans-atmospheric vehicles, such as the staging and propulsive strategies, take-off and landing solutions and aero-thermodynamic configurations. The presented selection algorithms exploit different types of high level requirements coming from Stakeholders’ Analysis, Market Outlook, Regulatory Framework Analysis and Strategic Plan, to support drivers and criteria definition process for the selection of the optimal solution among the alternatives. The theoretical description of each single algorithm is supported by the results obtained from the application of the methodology to a suborbital vehicle aimed at parabolic flight and to a point-to-point hypersonic transportation system. Eventually, suggestions for on-going software implementation of the algorithms as well as their integration within a complex conceptual and preliminary design workflow are provided

Flavor-oscillation clocks, continuous quantum measurements and a violation of Einstein equivalence principle

The relation between Einstein equivalence principle and a continuous quantum measurement is analyzed in the context of the recently proposed flavor-oscillation clocks, an idea pioneered by Ahluwalia and Burgard (Gen. Rel Grav. Errata 29, 681 (1997)). We will calculate the measurement outputs if a flavor-oscillation clock, which is immersed in a gravitational field, is subject to a continuous quantum measurement. Afterwards, resorting to the weak equivalence principle, we obtain the corresponding quantities in a freely falling reference frame. Finally, comparing this last result with the measurement outputs that would appear in a Minkowskian spacetime it will be found that they do not coincide, in other words, we have a violation of Einstein equivalence principle. This violation appears in two different forms, namely: (i) the oscillation frequency in a freely falling reference frame does not match with the case predicted by general relativity, a feature previously obtained by Ahluwalia; (ii) the probability distribution of the measurement outputs, obtained by an observer in a freely falling reference frame, does not coincide with the results that would appear in the case of a Minkowskian spacetime.Comment: 16 pages, accepted in Mod. Phys. Letts.

Long-time electron spin storage via dynamical suppression of hyperfine-induced decoherence in a quantum dot

The coherence time of an electron spin decohered by the nuclear spin environment in a quantum dot can be substantially increased by subjecting the electron to suitable dynamical decoupling sequences. We analyze the performance of high-level decoupling protocols by using a combination of analytical and exact numerical methods, and by paying special attention to the regimes of large inter-pulse delays and long-time dynamics, which are outside the reach of standard average Hamiltonian theory descriptions. We demonstrate that dynamical decoupling can remain efficient far beyond its formal domain of applicability, and find that a protocol exploiting concatenated design provides best performance for this system in the relevant parameter range. In situations where the initial electron state is known, protocols able to completely freeze decoherence at long times are constructed and characterized. The impact of system and control non-idealities is also assessed, including the effect of intra-bath dipolar interaction, magnetic field bias and bath polarization, as well as systematic pulse imperfections. While small bias field and small bath polarization degrade the decoupling fidelity, enhanced performance and temporal modulation result from strong applied fields and high polarizations. Overall, we find that if the relative errors of the control parameters do not exceed 5%, decoupling protocols can still prolong the coherence time by up to two orders of magnitude.Comment: 16 pages, 10 figures, submitted to Phys. Rev.

Sustainable supersonic fuel flow method: An evolution of the boeing fuel flow method for supersonic aircraft using sustainable aviation fuels

This paper discloses a new algorithm, called sustainable supersonic fuel flow method, to complement the conceptual design of future supersonic aircraft with pollutant and greenhouse gases emissions estimation. Starting from already existing algorithms currently used to assess the environmental impact of already developed and operating aircraft, the authors suggest revisions to improve the formulations, thus extending their application. Specifically, this paper has two objectives: to support the design of future supersonic aircraft and to evaluate the impact of the exploitation of more sustainable aviation fuels, with special focus on biofuels and biofuel blends, since the conceptual design stage. The core of the algorithm developed to predict in-flight emissions of a supersonic aircraft has been validated with public data of Concorde flight experiments. In addition, corrective factors accounting for the most recently developed and certified biofuels have been included in the formulation

Propellant subsystem design for hypersonic cruiser exploiting liquid hydrogen

The possibility of establishing a new paradigm for commercial aviation towards high-speed flight in the next decades shall be inevitably preceded by the increase of Technology Readiness Level for those relevant enabling technologies associated to propulsion, thermal management and on-board subsystems, with particular attention also to environmental sustainability and economic viability of the proposed concepts. New design methodologies for both aircraft and on-board subsystems design shall then be based on holistic approaches able to catch the strong interactions between vehicle configuration, mission and subsystems architecture, which characterize high-speed aircraft layouts. This paper proposes a methodology for the preliminary sizing of propellant subsystems for liquid hydrogen powered hypersonic cruisers. Making benefit of traditional approaches, the process aims at introducing new design aspects directly connected to the peculiar multifunctional architecture of on-board subsystems for high-speed vehicles, so to be able to include additional analyses in early design stages, especially in case of high level of on-board integration. Notably, impact of requirements for Center of Gravity control, thermal, and, in general, energy management are considered as integral part of the method, with crucial implications on architecture selection. After the introduction of design algorithms for subsystem sizing, the STRATOFLY MR3 hypersonic cruiser is taken as reference case study in order to provide a practical example of application of the proposed approach on a highly integrated platform