High level language-based robotic control system

This invention is a robot control system based on a high level language implementing a spatial operator algebra. There are two high level languages included within the system. At the highest level, applications programs can be written in a robot-oriented applications language including broad operators such as MOVE and GRASP. The robot-oriented applications language statements are translated into statements in the spatial operator algebra language. Programming can also take place using the spatial operator algebra language. The statements in the spatial operator algebra language from either source are then translated into machine language statements for execution by a digital control computer. The system also includes the capability of executing the control code sequences in a simulation mode before actual execution to assure proper action at execution time. The robot's environment is checked as part of the process and dynamic reconfiguration is also possible. The languages and system allow the programming and control of multiple arms and the use of inward/outward spatial recursions in which every computational step can be related to a transformation from one point in the mechanical robot to another point to name two major advantages

Why Chromatic Imaging Matters

During the last two decades, the first generation of beam combiners at the Very Large Telescope Interferometer has proved the importance of optical interferometry for high-angular resolution astrophysical studies in the near- and mid-infrared. With the advent of 4-beam combiners at the VLTI, the u-v coverage per pointing increases significantly, providing an opportunity to use reconstructed images as powerful scientific tools. Therefore, interferometric imaging is already a key feature of the new generation of VLTI instruments, as well as for other interferometric facilities like CHARA and JWST. It is thus imperative to account for the current image reconstruction capabilities and their expected evolutions in the coming years. Here, we present a general overview of the current situation of optical interferometric image reconstruction with a focus on new wavelength-dependent information, highlighting its main advantages and limitations. As an Appendix we include several cookbooks describing the usage and installation of several state-of-the art image reconstruction packages. To illustrate the current capabilities of the software available to the community, we recovered chromatic images, from simulated MATISSE data, using the MCMC software SQUEEZE. With these images, we aim at showing the importance of selecting good regularization functions and their impact on the reconstruction.Comment: Accepted for publication in Experimental Astronomy as part of the topical collection: Future of Optical-infrared Interferometry in Europ

Gaussian Quantum Information

The science of quantum information has arisen over the last two decades centered on the manipulation of individual quanta of information, known as quantum bits or qubits. Quantum computers, quantum cryptography and quantum teleportation are among the most celebrated ideas that have emerged from this new field. It was realized later on that using continuous-variable quantum information carriers, instead of qubits, constitutes an extremely powerful alternative approach to quantum information processing. This review focuses on continuous-variable quantum information processes that rely on any combination of Gaussian states, Gaussian operations, and Gaussian measurements. Interestingly, such a restriction to the Gaussian realm comes with various benefits, since on the theoretical side, simple analytical tools are available and, on the experimental side, optical components effecting Gaussian processes are readily available in the laboratory. Yet, Gaussian quantum information processing opens the way to a wide variety of tasks and applications, including quantum communication, quantum cryptography, quantum computation, quantum teleportation, and quantum state and channel discrimination. This review reports on the state of the art in this field, ranging from the basic theoretical tools and landmark experimental realizations to the most recent successful developments.Comment: 51 pages, 7 figures, submitted to Reviews of Modern Physic

Quantum Logical Gates with Linear Quadripartite Cluster States of Continuous Variables

The concrete schemes to realize three types of basic quantum logical gates using linear quadripartite cluster states of optical continuous variables are proposed. The influences of noises and finite squeezing on the computation precision are analyzed in terms of the fidelity of propagated quantum information through the continuous variable cluster states. The proposed schemes provide direct references for the design of experimental systems of one-way quantum computer based on the cluster entanglement of amplitude and phase quadratures of light.Comment: accepted for publication by PR

Simulating linear-optical quantum computers

Dissertação de mestrado integrado em Engineering Physics, Physics of InformationResearch in quantum computation has sharply increased in recent years, due to the promised computational advantage with respect to classical computers. Nowadays there are several proposals to encode quantum information. This dissertation discusses a particular type of quantum computer, based on linear optics. To support this approach, in this work we will investigate in detail the computational cost and challenges of simulating Boson Sampling and Gaussian Boson Sampling models to try to show quantum supremacy. The complexity of classical simulation is mainly due to the calculation of a very particular function for each case but several aspects can be considered to help minimize these costs; here we will discuss some of these aspects along with the most efficient proposals in the literature. First we will review some of the basic theory about linear and non-linear optics, a mature research topic. Thereafter, this theory will be applied to the two sampling-based quantum computational models we will study, followed by verification of computational complexity of them with some numerical experiments with our simulator. We use Python code, as well as an implementation using the Strawberry Fields library made available by Canadian company Xanadu, and which allows to use that code to run in an actual device. Besides demonstrations of quantum computational advantage, we also discuss useful applications of linear-optical quantum computation. These applications are diverse, ranging from graph theory to quantum chemistry, and use different encodings which we will discuss.Investigação em computação quântica aumentou consideravelmente nos últimos anos devido à promessa de vantagem computacional relativamente a computadores clássicos. Atualmente há várias propostas para codificar informação quântica. Esta dissertação foca-se num tipo de computador quântico particular baseado em ótica linear. Para suportar esta abordagem, neste trabalho será investigado em detalhe o custo computacional de simular os modelos de Amostragem Bosónica e Amostragem Bosónica Gaussiana e mostrar vantagem computacional quântica. A complexidade da simulação clássica deve-se principalmente ao cálculo de uma função muito particular para cada caso mas vários aspetos podem ser tomados em conta para ajudar a minimizar estes custos; serão discutidos alguns juntamente com as propostas mais eficientes da literatura. Primeiramente faremos uma revisão teórica sobre ótica linear e não linear, um tópico bastante desenvolvido. Posteriormente, será aplicada esta teoria aos dois modelos baseados em amostragem para computação, seguido da verificação da complexidade computacional dos mesmos juntamente com alguns testes numéricos com o nosso simulador. Nós usaremos código escrito em Python bem como uma implementação pela biblioteca Strawberry Fields disponibilizada pela empresa Xanadu que permite usar esse código para correr num dispositivo real. Além de demonstrar vantagem computacional quântica, também discutiremos aplicações úteis para computação quântica de ótica linear. Estas aplicações são diversas, desde teoria de grafos a química quântica, que usam diferentes codificações que discutiremos

When--and how--can a cellular automaton be rewritten as a lattice gas?

Both 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 term `cellular automaton' or `lattice gas' for the 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 (and by Durand--Lose for more than two dimensions) that any invertible CA can be rewritten as an LG (with a possibly much more complex ``unit cell''). 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.Comment: 16 page

Current research in cavitating fluid films

A review of the current research of cavitation in fluid films is presented. Phenomena and experimental observations include gaseous cavitation, vapor cavitation, and gas entrainment. Cavitation in flooded, starved, and dynamically loaded journal bearings, as well as squeeze films are reviewed. Observations of cavitation damage in bearings and the possibility of cavitation between parallel plates with microasperities were discussed. The transcavity fluid transport process, meniscus motion and geometry or form of the film during rupture, and reformation were summarized. Performance effects were related to heat transfer models in the cavitated region and hysteresis influence on rotor dynamics coefficients. A number of cavitation algorithms was presented together with solution procedures using the finite difference and finite element methods. Although Newtonian fluids were assumed in most of the discussions, the effect of non-Newtonian fluids on cavitation was also discussed