11,860,495 research outputs found
Using positive feedback adiabatic logic to implement reversible Toffoli gates
No full textA reversible, positive feedback adiabatic logic circuit is presented, which by implementing the universal Toffoli gate demonstrates that reversible logic circuits can be created and implemented using this adiabatic logic family. When compared to circuits with similar circuit structures that do not incorporate complete recovery logic, the use of reversible structures shows a reduction in energy losses by a mean of just under 63%
Introducing a Pan-European Project. An Ideological Profile of Volt Italia
No full textThe purpose of this essay is to provide a concise overview of Volt Europa – a new ecologist, rogressive and pan-European movement – with particular attention for its Italian section. Analysing the data I collected through an online questionnaire conducted in Spring 2020, I will examine the ideological orientation and the political collocation of Volt Italia within the Italian and European political landscape, providing some elements to understand its nature compared to other political forces and highlighting some characteristics that make it a political subject worthy of interest
Tribology at the atomic scale with density functional theory
No full textUnderstanding the quantum mechanical origins of friction forces has become increasingly important in the past decades with the advent of nanotechnology. At the nanometer scale, the universal Amontons-Coulomb laws cease to be valid and each interface requires individual scrutiny. Furthermore, measurements required to understand friction at the atomic scale are riddled with artificial factors such as the properties of the friction force microscope, effect of the environment, and the type of the substrate. It therefore proves difficult to isolate the actual behavior of interfaces from these effects. Electronic structure methods are an indispensable tool in understanding the details of interfaces, their interactions with lubricants, the environment and the support. In particular, density functional theory (DFT) has given large contributions to the field through accurate calculations of important properties such as the potential energy surfaces, shear strengths, adsorption of lubricant materials and the effect of the substrate. Although unable to tackle velocity- or temperature-dependent properties for which classical molecular dynamics is employed, DFT provides an affordable yet accurate means of understanding the quantum mechanical origins of the tribological behavior of interfaces in a parameter-free manner. This review attempts to give an overview of the ever-increasing literature on the use of DFT in the field of tribology. We start by summarizing the rich history of theoretical work on dry friction. We then identify the figures-of-merit which can be calculated using DFT. We follow by a summary of bulk interfaces and how to reduce friction via passivation and lubricants. The following section, namely friction involving two-dimensional materials is the focus of our review since these materials have gained increasing traction in the field thanks to the advanced manufacturing and manipulation techniques developed. Our review concludes with a brief touch on other interesting examples from DFT tribology literature such as rolling friction and the effect of photoexcitation in tribology
Exact SAT-based toffoli network synthesis
No full textCompact realizations of reversible logic functions are of interest in the design of quantum computers. Such reversible functions are realized as a cascade of Toffoli gates. In this paper, we present the first exact synthesis algorithm for reversible functions using generalized Toffoli gates. Our iterative algorithm formulates the synthesis problem with d Toffoli gates as a sequence of Boolean Satisfiability (SAT) instances. Such an instance is satisfiable iff there exists a network representation with d gates. Thus, we can guarantee minimality. In addition to fully specified reversible functions, the algorithm can be applied to incompletely specified functions. For a set of benchmarks experimental results are given
Adriatic Nanotechnologies
No full textPresentazione di una nuova generazione di strumenti dedicati ad ospedali, medici e pazienti per analizzare marcatori proteici quando e dove ce n'è bisogno.
Presentation of a new class of devices for medical used to analyze protein markers
When-and how- can a cellular automaton be rewritten as a lattice gas?
No full textAbstractBoth cellular automata (CA) and lattice-gas automata (LG) provide finite algorithmic presentations for certain classes of infinite dynamical systems studied by symbolic dynamics; it is customary to use the terms ‘cellular automaton’ and ‘lattice gas’ for a dynamic system itself as well as for its presentation. The two kinds of presentation share many traits but also display profound differences on issues ranging from decidability to modeling convenience and physical implementability.Following a conjecture by Toffoli and Margolus, it had been proved by Kari that any invertible CA, at least up to two dimensions, can be rewritten as an isomorphic LG. But until now it was not known whether this is possible in general for noninvertible CA—which comprise “almost all” CA and represent the bulk of examples in theory and applications. Even circumstantial evidence–whether in favor or against–was lacking.Here, for noninvertible CA, (a) we prove that an LG presentation is out of the question for the vanishingly small class of surjective ones. We then turn our attention to all the rest–noninvertible and nonsurjective–which comprise all the typical ones, including Conway’s ‘Game of Life’. For these (b) we prove by explicit construction that all the one-dimensional ones are representable as LG, and (c) we present and motivate the conjecture that this result extends to any number of dimensions.The tradeoff between dissipation rate and structural complexity implied by the above results have compelling implications for the thermodynamics of computation at a microscopic scale
Asymptotically Improved Circuit for -ary Grover's Algorithm with Advanced Decomposition of -qudit Toffoli Gate
No full textThe progress in building quantum computers to execute quantum algorithms has
recently been remarkable. Grover's search algorithm in a binary quantum system
provides considerable speed-up over classical paradigm. Further, Grover's
algorithm can be extended to a -ary (qudit) quantum system for utilizing the
advantage of larger state space, which helps to reduce the run-time of the
algorithm as compared to the traditional binary quantum systems. In a qudit
quantum system, an -qudit Toffoli gate plays a significant role in the
accurate implementation of Grover's algorithm. In this article, a generalized
-qudit Toffoli gate has been realized using higher dimensional qudits to
attain a logarithmic depth decomposition without ancilla qudit. The circuit for
Grover's algorithm has then been designed for any -ary quantum system, where
, with the proposed -qudit Toffoli gate to obtain optimized depth
compared to earlier approaches. The technique for decomposing an -qudit
Toffoli gate requires access to two immediately higher energy levels, making
the design susceptible to errors. Nevertheless, we show that the percentage
decrease in the probability of error is significant as we have reduced both
gate count and circuit depth as compared to that in state-of-the-art works.Comment: 15 pages, 9 figure
Density functional theory for molecular multiphoton ionization in the perturbative regime
No full textA general implementation of the lowest nonvanishing order perturbation theory for the calculation of molecular multiphoton ionization cross sections is proposed in the framework of density functional theory. Bound and scattering wave functions are expanded in a multicentric basis set and advantage is taken of the full molecular point group symmetry, thus enabling the application of the formalism to medium-size molecules. Multiphoton ionization cross sections and angular asymmetry parameters have been calculated for the two- and four-photon ionization of the H2+ molecule, for linear and circular light polarizations. Both fixed and random orientations of the target molecule have been considered. To demonstrate the efficiency of the proposed methodology, the two-photon cross section and angular asymmetry parameters for the HOMO and HOMO-1 orbital ionization of benzene are also presented
Asymptotically improved circuit for a d -ary Grover\u27s algorithm with advanced decomposition of the n -qudit Toffoli gate
No full textThe progress in building quantum computers to execute quantum algorithms has recently been remarkable. Grover\u27s search algorithm in a binary quantum system provides a considerable speed-up over the classical paradigm. It can be extended to a d-ary (qudit) quantum system also for utilizing the advantage of larger state space, which helps to reduce the runtime of the algorithm as compared to the traditional binary quantum systems. In a qudit quantum system, an n-qudit Toffoli gate plays a significant role in the accurate implementation of Grover\u27s algorithm. In this article, a generalized n-qudit Toffoli gate is realized using higher-dimensional qudits to attain a logarithmic depth decomposition without ancilla qudit. The circuit for Grover\u27s algorithm has then been designed for any d-ary quantum system, where d≥2, with the proposed n-qudit Toffoli gate to obtain optimized depth compared to earlier approaches. The technique for decomposing an n-qudit Toffoli gate requires access to two immediately higher-energy levels, making the design susceptible to errors. Nevertheless, we show that the percentage decrease in the probability of error is significant with both gate count and circuit depth reduced as compared to that in state-of-the-art works
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