25 research outputs found

    Space programs summary no. 37-39, volume III FOR the period March 1 to April 30, 1966. The deep space network

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    Deep Space Network ground communications system - system design, tracking and navigation accuracy, communications research and development engineering, and tracking station

    Engineering coherent control of quantum information in spin systems

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Science and Engineering, 2007.Includes bibliographical references (p. 151-161).Quantum Information Processing (QIP) promises increased efficiency in computation. A key step in QIP is implementing quantum logic gates by engineering the dynamics of a quantum system. This thesis explores the requirements and methods of coherent control in the context of magnetic resonance for: (i) nuclear spins of small molecules in solution and (ii) nuclear and electron spins in single crystals. The power of QIP is compromised in the presence of decoherence. One method of protecting information from collective decoherence is to limit the quantum states to those respecting the symmetry of the noise. These decoherence-free subspaces (DFS) encode one logical quantum bit (qubit) within multiple physical qubits. In many cases, such as nuclear magnetic resonance (NMR), the control Hamiltonians required for gate engineering leak the information outside the DFS, whereby protection is lost: It is shown how one can still perform universal logic among encoded qubits in the presence of leakage. These ideas are demonstrated on four carbon-13 spins of a small molecule in solution. Liquid phase NMR has shortcomings for QIP, like the lack of strong measurement and low polarization. These two problems can be addressed by moving to solid-state spin systems and incorporating electron spins. If the hyperfine interaction has an anisotropic character, it is proven that the composite system of one electron and N nuclear spins (le-Nn) is completely controllable by addressing only to the electron spin. This 'electron spin actuator' allows for faster gates between the nuclear spins than would be achievable in its absence. In addition, a scheme using logical qubit encodings is proposed for removing the added decoherence due to the electron spin. Lastly, this thesis exemplifies arbitrary gate engineering in a le-ln ensemble solid-sate spin system using a home-built ESR spectrometer designed specifically for engineering high-fidelity quantum control.by Jonathan Stuart Hodges.Ph.D

    Modular Understanding: A Taxonomy and Toolkit for Designing Modularity in Audio Software and Hardware

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    Modular synthesis is a continually evolving practice. Currently, an eectivetaxonomy for analyzing modular synthesizer design does not exist, which isa signicant barrier for pedagogy and documentation. In this dissertation,I will dene new taxonomies for modular control, patching strategies, andpanel design. I will also analyze how these taxonomies can be used to in-uence the design of musical applications outside of hardware, such as mycompany Unltered Audio's software products. Finally, I will present EuroReakt, my collection of over 140 module designs for the Reaktor Blocks formatand walk through the design process of each

    Dynamic nuclear polarization in biomolecular solid state NMR : methods and applications in peptides and membrane proteins

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2007.Includes bibliographical references.Solid state NMR can probe structure and dynamics on length scales from the atomic to the supramolecular. However, low sensitivity limits its application in macromolecules. NMR sensitivity can be improved by dynamic nuclear polarization (DNP), in which electron polarization is transferred to nuclei. We present applications of magic angle spinning NMR that demonstrate its utility for the determination of structure at atomic resolution. We then present new techniques and instrumentation for DNP that permit these methods to be applied to larger systems such as membrane proteins. These applications rest on several advances in instrumentation: millimeter-wave sources and conduits of power to the sample; low-temperature MAS probes incorporating millimeter-wave transmission; cryogenics and pneumatic control systems. We describe a 380 MHz DNP spectrometer incorporating a 250 GHz gyrotron oscillator and present the theory and operation of a 460 GHz gyrotron at the second harmonic of electron cyclotron resonance. We have applied DNP to study trapped photo cycle intermediates of the archael membrane protein bacteriorhodopsin, a light-driven transmembrane ion pump.(cont.) We have observed the K photointermediate for the first time by NMR and found unexpected conformational heterogeneity in the L intermediate. With multidimensional correlation spectroscopy, we have assigned active site resonances in conformational mixtures of photointermediates of [U-13C,'SN]-bR with high sensitivity. By using non-linear sampling of indirect dimensions, we have observed transient product of K accumulation. We present frequency-selective experiments for amino acid-selective assignments and the measurement of heteronuclear distances and torsion angles in [U-13C, N]-bR and discuss the relevance of these results to its photocycle. In addition, we describe several applications of solid state NMR, including a study of dynamic and structural phase transitions in peptides and proteins near the canonical glass transition temperature. We present resonance width experiments that can be used to measure homonuclear and heteronuclear dipolar couplings in uniformly labeled solids.(cont.) Finally, we discuss applications to amyloid fibrils, which are protein aggregates that are implicated in diseases of protein misfolding. We report the atomic resolution structure of the disease-associated L 111M mutant of TTR105-115 in an amyloid fibril, and information about the supramolecular structure of fibrils from WT TTRos05115.by Vikram Singh Bajaj.Ph.D

    Faculty Publications and Creative Works 2004

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    Faculty Publications & Creative Works is an annual compendium of scholarly and creative activities of University of New Mexico faculty during the noted calendar year. Published by the Office of the Vice President for Research and Economic Development, it serves to illustrate the robust and active intellectual pursuits conducted by the faculty in support of teaching and research at UNM

    News and reports from high energy density generated by heavy ion and laser beams : 2015

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    Space Programs Summary no. 37-38, volume IV FOR the period February 1, 1966 to March 31, 1966. Supporting research and advanced development

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    Supporting research in systems analysis, guidance and control, environmental simulation, space sciences, propulsion systems, and radio telecommunication
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