Efficient classical simulation of spin networks

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Physics, 2006.Includes bibliographical references (p. 45).In general, quantum systems are believed to be exponentially hard to simulate using classical computers. It is in these hard cases where we hope to find quantum algorithms that provide speed up over classical algorithms. In the paradigm of quantum adiabatic computation, instances of spin networks with 2-local interactions could hopefully efficiently compute certain problems in NP-complete. Thus, we are interested in the adiabatic evolution of spin networks. There are analytical solutions to specific Hamiltonians for 1D spin chains. However, analytical solutions to networks of higher dimensionality are unknown. The dynamics of Cayley trees (three binary trees connected at the root) at zero temperature are unknown. The running time of the adiabatic evolution of Cayley trees could provide an insight into the dynamics of more complicated spin networks. Matrix Product States (MPS) define a wavefunction anzatz that approximates slightly entangled quantum systems using poly(n) parameters. The MPS representation is exponentially smaller than the exact representation, which involves 0(2n) parameters. The MPS Algorithm evolves states in the MPS representation.(cont.) We present an extension to the DMRG algorithm that computes an approximation to the adiabatic evolution of Cayley trees with rotationally-symmetric 2-local Hamiltonians in time polynomial in the depth of the tree. This algorithm takes advantage of the symmetry of the Hamiltonian to evolve the state of a Cayley tree exponentially faster than using the standard DMRG algorithm. In this thesis, we study the time-evolution of two local Hamiltonians in a spin chain and a Cayley tree. The numerical results of the modified MPS algorithm can provide an estimate on the entropy of entanglement present in ground states of Cayley trees. Furthermore, the study of the Cayley tree explores the dynamics of fractional-dimensional spin networks.by Igor Andrade Sylvester.S.B

A hierarchical systems knowledge representation framework

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 57-58).We present the design and implementation of a framework for storing and analysing knowledge about engineering systems. The hierarchical entity-relation-attribute model is useful for large data sets, in which it can abstract details so that human users are able to reason about the data. The time-series extension to the model abstracts temporal details. Finally, the implementation of the model includes an execution engine that can simulate the model in one time-slice or as a function of time.by Igor Andrade Sylvester.M.Eng

The Quantum Transverse Field Ising Model on an Infinite Tree from Matrix Product States

We give a generalization to an infinite tree geometry of Vidal's infinite time-evolving block decimation (iTEBD) algorithm for simulating an infinite line of quantum spins. We numerically investigate the quantum Ising model in a transverse field on the Bethe lattice using the Matrix Product State ansatz. We observe a second order phase transition, with certain key differences from the transverse field Ising model on an infinite spin chain. We also investigate a transverse field Ising model with a specific longitudinal field. When the transverse field is turned off, this model has a highly degenerate ground state as opposed to the pure Ising model whose ground state is only doubly degenerate.Comment: 28 pages, 23 figures, PDFlate

Masters in Serious Games Curriculum Framework

Thin, A. G., Lim, T., Louchart, S., De Gloria, A., Mayer, I., Kickmeier-Rust, M., Klamma, R., VeltKamp, R., Arnab, S., Bellotti, F., Boyle, L., Prada, R., Westera, W., Nadolski, R., & Abbas Petersen, S. (2013). Masters in Serious Games Curriculum Framework. Deliverable 5.3 of the Games and Learning Alliance Network of Excellence. Available at http://www.seriousgamessociety.org/download/SGMastersFwk.pdf.This report outlines a European Masters of Science programme on serious gaming.This report is a deliverable of the GALA project, which is sponsored by the the FP7 Programme of the European Commissio

ENIGMA-anxiety working group : Rationale for and organization of large-scale neuroimaging studies of anxiety disorders

Altres ajuts: Anxiety Disorders Research Network European College of Neuropsychopharmacology; Claude Leon Postdoctoral Fellowship; Deutsche Forschungsgemeinschaft (DFG, German Research Foundation, 44541416-TRR58); EU7th Frame Work Marie Curie Actions International Staff Exchange Scheme grant 'European and South African Research Network in Anxiety Disorders' (EUSARNAD); Geestkracht programme of the Netherlands Organization for Health Research and Development (ZonMw, 10-000-1002); Intramural Research Training Award (IRTA) program within the National Institute of Mental Health under the Intramural Research Program (NIMH-IRP, MH002781); National Institute of Mental Health under the Intramural Research Program (NIMH-IRP, ZIA-MH-002782); SA Medical Research Council; U.S. National Institutes of Health grants (P01 AG026572, P01 AG055367, P41 EB015922, R01 AG060610, R56 AG058854, RF1 AG051710, U54 EB020403).Anxiety disorders are highly prevalent and disabling but seem particularly tractable to investigation with translational neuroscience methodologies. Neuroimaging has informed our understanding of the neurobiology of anxiety disorders, but research has been limited by small sample sizes and low statistical power, as well as heterogenous imaging methodology. The ENIGMA-Anxiety Working Group has brought together researchers from around the world, in a harmonized and coordinated effort to address these challenges and generate more robust and reproducible findings. This paper elaborates on the concepts and methods informing the work of the working group to date, and describes the initial approach of the four subgroups studying generalized anxiety disorder, panic disorder, social anxiety disorder, and specific phobia. At present, the ENIGMA-Anxiety database contains information about more than 100 unique samples, from 16 countries and 59 institutes. Future directions include examining additional imaging modalities, integrating imaging and genetic data, and collaborating with other ENIGMA working groups. The ENIGMA consortium creates synergy at the intersection of global mental health and clinical neuroscience, and the ENIGMA-Anxiety Working Group extends the promise of this approach to neuroimaging research on anxiety disorders

GTX: The MARCO GSRC Technology Extrapolation System

Technology extrapolation --- the calibration and prediction of achievable design in future technology generations -- drives the evolution of VLSI system architectures, design methodologies, and design tools. This paper describes initial experiences with development and use of GTX, the MARCO GSRC Technology Extrapolation system. GTX provides a robust, portable framework for interactive specification and comparison of modeling choices, e.g., for predicting system cycle time, die size and power dissipation. We use GTX to reveal surprising levels of uncertainty (modeling and parameter sensitivity) in widely-cited cycle-time models that drive recent roadmaps. We also describe new SOI and bulk device models that have been developed for GTX, as well as studies of power dissipation and delay uncertainty under various implementation assumptions for global interconnects