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Sample records for quantum computer architectures

  1. Layered Architectures for Quantum Computers and Quantum Repeaters

    NASA Astrophysics Data System (ADS)

    Jones, Nathan C.

    This chapter examines how to organize quantum computers and repeaters using a systematic framework known as layered architecture, where machine control is organized in layers associated with specialized tasks. The framework is flexible and could be used for analysis and comparison of quantum information systems. To demonstrate the design principles in practice, we develop architectures for quantum computers and quantum repeaters based on optically controlled quantum dots, showing how a myriad of technologies must operate synchronously to achieve fault-tolerance. Optical control makes information processing in this system very fast, scalable to large problem sizes, and extendable to quantum communication.

  2. Topological Code Architectures for Quantum Computation

    NASA Astrophysics Data System (ADS)

    Cesare, Christopher Anthony

    This dissertation is concerned with quantum computation using many-body quantum systems encoded in topological codes. The interest in these topological systems has increased in recent years as devices in the lab begin to reach the fidelities required for performing arbitrarily long quantum algorithms. The most well-studied system, Kitaev's toric code, provides both a physical substrate for performing universal fault-tolerant quantum computations and a useful pedagogical tool for explaining the way other topological codes work. In this dissertation, I first review the necessary formalism for quantum information and quantum stabilizer codes, and then I introduce two families of topological codes: Kitaev's toric code and Bombin's color codes. I then present three chapters of original work. First, I explore the distinctness of encoding schemes in the color codes. Second, I introduce a model of quantum computation based on the toric code that uses adiabatic interpolations between static Hamiltonians with gaps constant in the system size. Lastly, I describe novel state distillation protocols that are naturally suited for topological architectures and show that they provide resource savings in terms of the number of required ancilla states when compared to more traditional approaches to quantum gate approximation.

  3. Analysis of an Atom-Optical Architecture for Quantum Computation

    NASA Astrophysics Data System (ADS)

    Devitt, Simon J.; Stephens, Ashley M.; Munro, William J.; Nemoto, Kae

    Quantum technology based on photons has emerged as one of the most promising platforms for quantum information processing, having already been used in proof-of-principle demonstrations of quantum communication and quantum computation. However, the scalability of this technology depends on the successful integration of experimentally feasible devices in an architecture that tolerates realistic errors and imperfections. Here, we analyse an atom-optical architecture for quantum computation designed to meet the requirements of scalability. The architecture is based on a modular atom-cavity device that provides an effective photon-photon interaction, allowing for the rapid, deterministic preparation of a large class of entangled states. We begin our analysis at the physical level, where we outline the experimental cavity quantum electrodynamics requirements of the basic device. Then, we describe how a scalable network of these devices can be used to prepare a three-dimensional topological cluster state, sufficient for universal fault-tolerant quantum computation. We conclude at the application level, where we estimate the system-level requirements of the architecture executing an algorithm compiled for compatibility with the topological cluster state.

  4. Scalable quantum computer architecture with coupled donor-quantum dot qubits

    DOEpatents

    Schenkel, Thomas; Lo, Cheuk Chi; Weis, Christoph; Lyon, Stephen; Tyryshkin, Alexei; Bokor, Jeffrey

    2014-08-26

    A quantum bit computing architecture includes a plurality of single spin memory donor atoms embedded in a semiconductor layer, a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, wherein a first voltage applied across at least one pair of the aligned quantum dot and donor atom controls a donor-quantum dot coupling. A method of performing quantum computing in a scalable architecture quantum computing apparatus includes arranging a pattern of single spin memory donor atoms in a semiconductor layer, forming a plurality of quantum dots arranged with the semiconductor layer and aligned with the donor atoms, applying a first voltage across at least one aligned pair of a quantum dot and donor atom to control a donor-quantum dot coupling, and applying a second voltage between one or more quantum dots to control a Heisenberg exchange J coupling between quantum dots and to cause transport of a single spin polarized electron between quantum dots.

  5. QNIX: A Linear Optical Architecture for Quantum Computing

    NASA Astrophysics Data System (ADS)

    Gimeno-Segovia, Mercedes; Shadbolt, Peter J.; Rudolph, Terry G.; Browne, Dan E.; Mendoza, Gabriel; Russell, Nicholas J.; Silverstone, Joshua W.; Santamato, Alberto; Carolan, Jacques; O'Brien, Jeremy

    2015-03-01

    There is currently a great deal of effort to develop a large-scale quantum computer, and one of the most promising platforms to do so is integrated linear optics. We present a proposal for a dynamical scheme for an integrated linear optics implementation of a one-way quantum computer. We go beyond the purely theoretical work and address practical issues in order to create a physically realistic design. We describe every step of cluster state construction and processing, showing the outstanding issues left to be addressed and our contributions to the different stages of the dynamical process. These include optimised interferometers for the generation of GHZ states, a universal and scalable architecture which requires entangled sources of no more than 3 photons with no active feed-forward, and loss-tolerant and fault-tolerant strategies specifically tailored to our proposed architecture. Our work demonstrates that building a linear optical quantum computer need be less challenging than previously thought, and brings large-scale switch-free linear optical architectures for quantum computing much closer to experimental realisation.

  6. Quantum perceptron over a field and neural network architecture selection in a quantum computer.

    PubMed

    da Silva, Adenilton José; Ludermir, Teresa Bernarda; de Oliveira, Wilson Rosa

    2016-04-01

    In this work, we propose a quantum neural network named quantum perceptron over a field (QPF). Quantum computers are not yet a reality and the models and algorithms proposed in this work cannot be simulated in actual (or classical) computers. QPF is a direct generalization of a classical perceptron and solves some drawbacks found in previous models of quantum perceptrons. We also present a learning algorithm named Superposition based Architecture Learning algorithm (SAL) that optimizes the neural network weights and architectures. SAL searches for the best architecture in a finite set of neural network architectures with linear time over the number of patterns in the training set. SAL is the first learning algorithm to determine neural network architectures in polynomial time. This speedup is obtained by the use of quantum parallelism and a non-linear quantum operator. PMID:26878722

  7. Cryogenic Control Architecture for Large-Scale Quantum Computing

    NASA Astrophysics Data System (ADS)

    Hornibrook, J. M.; Colless, J. I.; Conway Lamb, I. D.; Pauka, S. J.; Lu, H.; Gossard, A. C.; Watson, J. D.; Gardner, G. C.; Fallahi, S.; Manfra, M. J.; Reilly, D. J.

    2015-02-01

    Solid-state qubits have recently advanced to the level that enables them, in principle, to be scaled up into fault-tolerant quantum computers. As these physical qubits continue to advance, meeting the challenge of realizing a quantum machine will also require the development of new supporting devices and control architectures with complexity far beyond the systems used in today's few-qubit experiments. Here, we report a microarchitecture for controlling and reading out qubits during the execution of a quantum algorithm such as an error-correcting code. We demonstrate the basic principles of this architecture using a cryogenic switch matrix implemented via high-electron-mobility transistors and a new kind of semiconductor device based on gate-switchable capacitance. The switch matrix is used to route microwave waveforms to qubits under the control of a field-programmable gate array, also operating at cryogenic temperatures. Taken together, these results suggest a viable approach for controlling large-scale quantum systems using semiconductor technology.

  8. An architecture for quantum computation with magnetically trapped Holmium atoms

    NASA Astrophysics Data System (ADS)

    Saffman, Mark; Hostetter, James; Booth, Donald; Collett, Jeffrey

    2016-05-01

    Outstanding challenges for scalable neutral atom quantum computation include correction of atom loss due to collisions with untrapped background gas, reduction of crosstalk during state preparation and measurement due to scattering of near resonant light, and the need to improve quantum gate fidelity. We present a scalable architecture based on loading single Holmium atoms into an array of Ioffe-Pritchard traps. The traps are formed by grids of superconducting wires giving a trap array with 40 μm period, suitable for entanglement via long range Rydberg gates. The states | F = 5 , M = 5 > and | F = 7 , M = 7 > provide a magic trapping condition at a low field of 3.5 G for long coherence time qubit encoding. The F = 11 level will be used for state preparation and measurement. The availability of different states for encoding, gate operations, and measurement, spectroscopically isolates the different operations and will prevent crosstalk to neighboring qubits. Operation in a cryogenic environment with ultra low pressure will increase atom lifetime and Rydberg gate fidelity by reduction of blackbody induced Rydberg decay. We will present a complete description of the architecture including estimates of achievable performance metrics. Work supported by NSF award PHY-1404357.

  9. Spin-qubit inspired architectures for superconducting quantum computing

    NASA Astrophysics Data System (ADS)

    Shim, Yun-Pil; Tahan, Charles

    2015-03-01

    In recent years, the superconducting qubit community has achieved single and two-qubit benchmarked gate fidelities approaching 99.9%, fast readout with novel superconducting amplifiers, distributed entanglement, and other milestones on the road to fault-tolerant quantum information processing. Obviously, this is a field that could use some help from the semiconductor qubit community! Here we present theoretical work on superconducting qubit systems inspired by our experience with semiconductor qubits. We discuss initialization, single- and two-qubit gate operations, and measurement schemes for an encoded qubit in a two-dimensional architecture. Our results motivate new ways of designing or operating superconducting quantum information processors.

  10. Quantum Computing

    NASA Astrophysics Data System (ADS)

    Steffen, Matthias

    2013-03-01

    Quantum mechanics plays a crucial role in many day-to-day products, and has been successfully used to explain a wide variety of observations in Physics. While some quantum effects such as tunneling limit the degree to which modern CMOS devices can be scaled to ever reducing dimensions, others may potentially be exploited to build an entirely new computing architecture: The quantum computer. In this talk I will review several basic concepts of a quantum computer. Why quantum computing and how do we do it? What is the status of several (but not all) approaches towards building a quantum computer, including IBM's approach using superconducting qubits? And what will it take to build a functional machine? The promise is that a quantum computer could solve certain interesting computational problems such as factoring using exponentially fewer computational steps than classical systems. Although the most sophisticated modern quantum computing experiments to date do not outperform simple classical computations, it is increasingly becoming clear that small scale demonstrations with as many as 100 qubits are beginning to be within reach over the next several years. Such a demonstration would undoubtedly be a thrilling feat, and usher in a new era of controllably testing quantum mechanics or quantum computing aspects. At the minimum, future demonstrations will shed much light on what lies ahead.

  11. Architecture Framework for Trapped-Ion Quantum Computer based on Performance Simulation Tool

    NASA Astrophysics Data System (ADS)

    Ahsan, Muhammad

    The challenge of building scalable quantum computer lies in striking appropriate balance between designing a reliable system architecture from large number of faulty computational resources and improving the physical quality of system components. The detailed investigation of performance variation with physics of the components and the system architecture requires adequate performance simulation tool. In this thesis we demonstrate a software tool capable of (1) mapping and scheduling the quantum circuit on a realistic quantum hardware architecture with physical resource constraints, (2) evaluating the performance metrics such as the execution time and the success probability of the algorithm execution, and (3) analyzing the constituents of these metrics and visualizing resource utilization to identify system components which crucially define the overall performance. Using this versatile tool, we explore vast design space for modular quantum computer architecture based on trapped ions. We find that while success probability is uniformly determined by the fidelity of physical quantum operation, the execution time is a function of system resources invested at various layers of design hierarchy. At physical level, the number of lasers performing quantum gates, impact the latency of the fault-tolerant circuit blocks execution. When these blocks are used to construct meaningful arithmetic circuit such as quantum adders, the number of ancilla qubits for complicated non-clifford gates and entanglement resources to establish long-distance communication channels, become major performance limiting factors. Next, in order to factorize large integers, these adders are assembled into modular exponentiation circuit comprising bulk of Shor's algorithm. At this stage, the overall scaling of resource-constraint performance with the size of problem, describes the effectiveness of chosen design. By matching the resource investment with the pace of advancement in hardware technology

  12. Simulation of Si:P spin-based quantum computer architecture

    SciTech Connect

    Chang Yiachung; Fang Angbo

    2008-11-07

    We present realistic simulation for single and double phosphorous donors in a silicon-based quantum computer design by solving a valley-orbit coupled effective-mass equation for describing phosphorous donors in strained silicon quantum well (QW). Using a generalized unrestricted Hartree-Fock method, we solve the two-electron effective-mass equation with quantum well confinement and realistic gate potentials. The effects of QW width, gate voltages, donor separation, and donor position shift on the lowest singlet and triplet energies and their charge distributions for a neighboring donor pair in the quantum computer(QC) architecture are analyzed. The gate tunability are defined and evaluated for a typical QC design. Estimates are obtained for the duration of spin half-swap gate operation.

  13. Toward a scalable quantum computing architecture with mixed species ion chains

    NASA Astrophysics Data System (ADS)

    Wright, John; Auchter, Carolyn; Chou, Chen-Kuan; Graham, Richard D.; Noel, Thomas W.; Sakrejda, Tomasz; Zhou, Zichao; Blinov, Boris B.

    2016-01-01

    We report on progress toward implementing mixed ion species quantum information processing for a scalable ion-trap architecture. Mixed species chains may help solve several problems with scaling ion-trap quantum computation to large numbers of qubits. Initial temperature measurements of linear Coulomb crystals containing barium and ytterbium ions indicate that the mass difference does not significantly impede cooling at low ion numbers. Average motional occupation numbers are estimated to be bar{n} ≈ 130 quanta per mode for chains with small numbers of ions, which is within a factor of three of the Doppler limit for barium ions in our trap. We also discuss generation of ion-photon entanglement with barium ions with a fidelity of F ≥ 0.84 , which is an initial step towards remote ion-ion coupling in a more scalable quantum information architecture. Further, we are working to implement these techniques in surface traps in order to exercise greater control over ion chain ordering and positioning.

  14. Robust quantum gates and a bus architecture for quantum computing with rare-earth-ion-doped crystals

    SciTech Connect

    Wesenberg, Janus; Moelmer, Klaus

    2003-07-01

    We present a composite pulse controlled phase gate which, together with a bus architecture, improves the feasibility of a recent quantum computing proposal based on rare-earth-ion-doped crystals. The proposed gate operation is tolerant to variations between ions of coupling strengths, pulse lengths, and frequency shifts. In the absence of decoherence effects, it achieves worst case fidelities above 0.999 with relative variations in coupling strength as high as 10% and frequency shifts up to several percent of the resonant Rabi frequency of the laser used to implement the gate. We outline an experiment to demonstrate the creation and detection of maximally entangled states in the system.

  15. New computer architectures

    SciTech Connect

    Tiberghien, J.

    1984-01-01

    This book presents papers on supercomputers. Topics considered include decentralized computer architecture, new programming languages, data flow computers, reduction computers, parallel prefix calculations, structural and behavioral descriptions of digital systems, instruction sets, software generation, personal computing, and computer architecture education.

  16. Quantum Computation and Quantum Information

    NASA Astrophysics Data System (ADS)

    Nielsen, Michael A.; Chuang, Isaac L.

    2010-12-01

    Part I. Fundamental Concepts: 1. Introduction and overview; 2. Introduction to quantum mechanics; 3. Introduction to computer science; Part II. Quantum Computation: 4. Quantum circuits; 5. The quantum Fourier transform and its application; 6. Quantum search algorithms; 7. Quantum computers: physical realization; Part III. Quantum Information: 8. Quantum noise and quantum operations; 9. Distance measures for quantum information; 10. Quantum error-correction; 11. Entropy and information; 12. Quantum information theory; Appendices; References; Index.

  17. Physical Architecture for a Universal Topological Quantum Computer based on a Network of Majorana Nanowires

    NASA Astrophysics Data System (ADS)

    Sau, Jay; Barkeshli, Maissam

    The idea of topological quantum computation (TQC) is to encode and manipulate quantum information in an intrinsically fault-tolerant manner by utilizing the physics of topologically ordered phases of matter. Currently, the most promising platforms for a topological qubit are either in terms of Majorana fermion zero modes (MZMs) in spin-orbit coupled superconducting nanowires or in terms of the Kitaev Z2 surface code. However, the topologically robust operations that are possible in these systems are not sufficient for realizing a universal gate set for topological quantum computation. Here, we show that an array of coupled semiconductor/superconductor nanowires with MZM edge states can be used to realize a more sophisticated type of non-Abelian defect, a genon in an Ising X Ising topological state. This leads to a possible implementation of the missing topologically protected pi/8 phase gate and thus paves a path for universal topological quantum computation based on semiconductor-superconductor nanowire technology. We provide detailed numerical estimates of the relevant energy scales, which we show to lie within accessible ranges. J. S. was supported by Microsoft Station Q, startup funds from the University of Maryland and NSF-JQI-PFC.

  18. Architecture Adaptive Computing Environment

    NASA Technical Reports Server (NTRS)

    Dorband, John E.

    2006-01-01

    Architecture Adaptive Computing Environment (aCe) is a software system that includes a language, compiler, and run-time library for parallel computing. aCe was developed to enable programmers to write programs, more easily than was previously possible, for a variety of parallel computing architectures. Heretofore, it has been perceived to be difficult to write parallel programs for parallel computers and more difficult to port the programs to different parallel computing architectures. In contrast, aCe is supportable on all high-performance computing architectures. Currently, it is supported on LINUX clusters. aCe uses parallel programming constructs that facilitate writing of parallel programs. Such constructs were used in single-instruction/multiple-data (SIMD) programming languages of the 1980s, including Parallel Pascal, Parallel Forth, C*, *LISP, and MasPar MPL. In aCe, these constructs are extended and implemented for both SIMD and multiple- instruction/multiple-data (MIMD) architectures. Two new constructs incorporated in aCe are those of (1) scalar and virtual variables and (2) pre-computed paths. The scalar-and-virtual-variables construct increases flexibility in optimizing memory utilization in various architectures. The pre-computed-paths construct enables the compiler to pre-compute part of a communication operation once, rather than computing it every time the communication operation is performed.

  19. Highly Parallel Computing Architectures by using Arrays of Quantum-dot Cellular Automata (QCA): Opportunities, Challenges, and Recent Results

    NASA Technical Reports Server (NTRS)

    Fijany, Amir; Toomarian, Benny N.

    2000-01-01

    There has been significant improvement in the performance of VLSI devices, in terms of size, power consumption, and speed, in recent years and this trend may also continue for some near future. However, it is a well known fact that there are major obstacles, i.e., physical limitation of feature size reduction and ever increasing cost of foundry, that would prevent the long term continuation of this trend. This has motivated the exploration of some fundamentally new technologies that are not dependent on the conventional feature size approach. Such technologies are expected to enable scaling to continue to the ultimate level, i.e., molecular and atomistic size. Quantum computing, quantum dot-based computing, DNA based computing, biologically inspired computing, etc., are examples of such new technologies. In particular, quantum-dots based computing by using Quantum-dot Cellular Automata (QCA) has recently been intensely investigated as a promising new technology capable of offering significant improvement over conventional VLSI in terms of reduction of feature size (and hence increase in integration level), reduction of power consumption, and increase of switching speed. Quantum dot-based computing and memory in general and QCA specifically, are intriguing to NASA due to their high packing density (10(exp 11) - 10(exp 12) per square cm ) and low power consumption (no transfer of current) and potentially higher radiation tolerant. Under Revolutionary Computing Technology (RTC) Program at the NASA/JPL Center for Integrated Space Microelectronics (CISM), we have been investigating the potential applications of QCA for the space program. To this end, exploiting the intrinsic features of QCA, we have designed novel QCA-based circuits for co-planner (i.e., single layer) and compact implementation of a class of data permutation matrices, a class of interconnection networks, and a bit-serial processor. Building upon these circuits, we have developed novel algorithms and QCA

  20. Quantum Computation

    NASA Astrophysics Data System (ADS)

    Ekert, Artur

    1994-08-01

    As computers become faster they must become smaller because of the finiteness of the speed of light. The history of computer technology has involved a sequence of changes from one type of physical realisation to another - from gears to relays to valves to transistors to integrated circuits and so on. Quantum mechanics is already important in the design of microelectronic components. Soon it will be necessary to harness quantum mechanics rather than simply take it into account, and at that point it will be possible to give data processing devices new functionality.

  1. The Physics of Quantum Computation

    NASA Astrophysics Data System (ADS)

    Falci, Giuseppe; Paladino, Elisabette

    2015-10-01

    Quantum Computation has emerged in the past decades as a consequence of down-scaling of electronic devices to the mesoscopic regime and of advances in the ability of controlling and measuring microscopic quantum systems. QC has many interdisciplinary aspects, ranging from physics and chemistry to mathematics and computer science. In these lecture notes we focus on physical hardware, present day challenges and future directions for design of quantum architectures.

  2. Quantum walk computation

    SciTech Connect

    Kendon, Viv

    2014-12-04

    Quantum versions of random walks have diverse applications that are motivating experimental implementations as well as theoretical studies. Recent results showing quantum walks are “universal for quantum computation” relate to algorithms, to be run on quantum computers. We consider whether an experimental implementation of a quantum walk could provide useful computation before we have a universal quantum computer.

  3. Adiabatic Quantum Computing

    NASA Astrophysics Data System (ADS)

    Landahl, Andrew

    2012-10-01

    Quantum computers promise to exploit counterintuitive quantum physics principles like superposition, entanglement, and uncertainty to solve problems using fundamentally fewer steps than any conventional computer ever could. The mere possibility of such a device has sharpened our understanding of quantum coherent information, just as lasers did for our understanding of coherent light. The chief obstacle to developing quantum computer technology is decoherence--one of the fastest phenomena in all of physics. In principle, decoherence can be overcome by using clever entangled redundancies in a process called fault-tolerant quantum error correction. However, the quality and scale of technology required to realize this solution appears distant. An exciting alternative is a proposal called ``adiabatic'' quantum computing (AQC), in which adiabatic quantum physics keeps the computer in its lowest-energy configuration throughout its operation, rendering it immune to many decoherence sources. The Adiabatic Quantum Architectures In Ultracold Systems (AQUARIUS) Grand Challenge Project at Sandia seeks to demonstrate this robustness in the laboratory and point a path forward for future hardware development. We are building devices in AQUARIUS that realize the AQC architecture on up to three quantum bits (``qubits'') in two platforms: Cs atoms laser-cooled to below 5 microkelvin and Si quantum dots cryo-cooled to below 100 millikelvin. We are also expanding theoretical frontiers by developing methods for scalable universal AQC in these platforms. We have successfully demonstrated operational qubits in both platforms and have even run modest one-qubit calculations using our Cs device. In the course of reaching our primary proof-of-principle demonstrations, we have developed multiple spinoff technologies including nanofabricated diffractive optical elements that define optical-tweezer trap arrays and atomic-scale Si lithography commensurate with placing individual donor atoms with

  4. Quantum Computer Games: Quantum Minesweeper

    ERIC Educational Resources Information Center

    Gordon, Michal; Gordon, Goren

    2010-01-01

    The computer game of quantum minesweeper is introduced as a quantum extension of the well-known classical minesweeper. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. Quantum minesweeper demonstrates the effects of superposition, entanglement and their non-local characteristics. While in the classical…

  5. Quantum robots and quantum computers

    SciTech Connect

    Benioff, P.

    1998-07-01

    Validation of a presumably universal theory, such as quantum mechanics, requires a quantum mechanical description of systems that carry out theoretical calculations and systems that carry out experiments. The description of quantum computers is under active development. No description of systems to carry out experiments has been given. A small step in this direction is taken here by giving a description of quantum robots as mobile systems with on board quantum computers that interact with different environments. Some properties of these systems are discussed. A specific model based on the literature descriptions of quantum Turing machines is presented.

  6. Recursive computer architecture for VLSI

    SciTech Connect

    Treleaven, P.C.; Hopkins, R.P.

    1982-01-01

    A general-purpose computer architecture based on the concept of recursion and suitable for VLSI computer systems built from replicated (lego-like) computing elements is presented. The recursive computer architecture is defined by presenting a program organisation, a machine organisation and an experimental machine implementation oriented to VLSI. The experimental implementation is being restricted to simple, identical microcomputers each containing a memory, a processor and a communications capability. This future generation of lego-like computer systems are termed fifth generation computers by the Japanese. 30 references.

  7. Introduction to Quantum Computation

    NASA Astrophysics Data System (ADS)

    Ekert, A.

    A computation is a physical process. It may be performed by a piece of electronics or on an abacus, or in your brain, but it is a process that takes place in nature and as such it is subject to the laws of physics. Quantum computers are machines that rely on characteristically quantum phenomena, such as quantum interference and quantum entanglement in order to perform computation. In this series of lectures I want to elaborate on the computational power of such machines.

  8. Computing architecture for autonomous microgrids

    SciTech Connect

    Goldsmith, Steven Y.

    2015-09-29

    A computing architecture that facilitates autonomously controlling operations of a microgrid is described herein. A microgrid network includes numerous computing devices that execute intelligent agents, each of which is assigned to a particular entity (load, source, storage device, or switch) in the microgrid. The intelligent agents can execute in accordance with predefined protocols to collectively perform computations that facilitate uninterrupted control of the .

  9. Scalable optical quantum computer

    SciTech Connect

    Manykin, E A; Mel'nichenko, E V

    2014-12-31

    A way of designing a scalable optical quantum computer based on the photon echo effect is proposed. Individual rare earth ions Pr{sup 3+}, regularly located in the lattice of the orthosilicate (Y{sub 2}SiO{sub 5}) crystal, are suggested to be used as optical qubits. Operations with qubits are performed using coherent and incoherent laser pulses. The operation protocol includes both the method of measurement-based quantum computations and the technique of optical computations. Modern hybrid photon echo protocols, which provide a sufficient quantum efficiency when reading recorded states, are considered as most promising for quantum computations and communications. (quantum computer)

  10. Universal computation by multiparticle quantum walk.

    PubMed

    Childs, Andrew M; Gosset, David; Webb, Zak

    2013-02-15

    A quantum walk is a time-homogeneous quantum-mechanical process on a graph defined by analogy to classical random walk. The quantum walker is a particle that moves from a given vertex to adjacent vertices in quantum superposition. We consider a generalization to interacting systems with more than one walker, such as the Bose-Hubbard model and systems of fermions or distinguishable particles with nearest-neighbor interactions, and show that multiparticle quantum walk is capable of universal quantum computation. Our construction could, in principle, be used as an architecture for building a scalable quantum computer with no need for time-dependent control. PMID:23413349

  11. Massively parallel quantum computer simulator

    NASA Astrophysics Data System (ADS)

    De Raedt, K.; Michielsen, K.; De Raedt, H.; Trieu, B.; Arnold, G.; Richter, M.; Lippert, Th.; Watanabe, H.; Ito, N.

    2007-01-01

    We describe portable software to simulate universal quantum computers on massive parallel computers. We illustrate the use of the simulation software by running various quantum algorithms on different computer architectures, such as a IBM BlueGene/L, a IBM Regatta p690+, a Hitachi SR11000/J1, a Cray X1E, a SGI Altix 3700 and clusters of PCs running Windows XP. We study the performance of the software by simulating quantum computers containing up to 36 qubits, using up to 4096 processors and up to 1 TB of memory. Our results demonstrate that the simulator exhibits nearly ideal scaling as a function of the number of processors and suggest that the simulation software described in this paper may also serve as benchmark for testing high-end parallel computers.

  12. Quantum computer games: quantum minesweeper

    NASA Astrophysics Data System (ADS)

    Gordon, Michal; Gordon, Goren

    2010-07-01

    The computer game of quantum minesweeper is introduced as a quantum extension of the well-known classical minesweeper. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. Quantum minesweeper demonstrates the effects of superposition, entanglement and their non-local characteristics. While in the classical minesweeper the goal of the game is to discover all the mines laid out on a board without triggering them, in the quantum version there are several classical boards in superposition. The goal is to know the exact quantum state, i.e. the precise layout of all the mines in all the superposed classical boards. The player can perform three types of measurement: a classical measurement that probabilistically collapses the superposition; a quantum interaction-free measurement that can detect a mine without triggering it; and an entanglement measurement that provides non-local information. The application of the concepts taught by quantum minesweeper to one-way quantum computing are also presented.

  13. Algorithms versus architectures for computational chemistry

    NASA Technical Reports Server (NTRS)

    Partridge, H.; Bauschlicher, C. W., Jr.

    1986-01-01

    The algorithms employed are computationally intensive and, as a result, increased performance (both algorithmic and architectural) is required to improve accuracy and to treat larger molecular systems. Several benchmark quantum chemistry codes are examined on a variety of architectures. While these codes are only a small portion of a typical quantum chemistry library, they illustrate many of the computationally intensive kernels and data manipulation requirements of some applications. Furthermore, understanding the performance of the existing algorithm on present and proposed supercomputers serves as a guide for future programs and algorithm development. The algorithms investigated are: (1) a sparse symmetric matrix vector product; (2) a four index integral transformation; and (3) the calculation of diatomic two electron Slater integrals. The vectorization strategies are examined for these algorithms for both the Cyber 205 and Cray XMP. In addition, multiprocessor implementations of the algorithms are looked at on the Cray XMP and on the MIT static data flow machine proposed by DENNIS.

  14. Adiabatic topological quantum computing

    NASA Astrophysics Data System (ADS)

    Cesare, Chris; Landahl, Andrew J.; Bacon, Dave; Flammia, Steven T.; Neels, Alice

    2015-07-01

    Topological quantum computing promises error-resistant quantum computation without active error correction. However, there is a worry that during the process of executing quantum gates by braiding anyons around each other, extra anyonic excitations will be created that will disorder the encoded quantum information. Here, we explore this question in detail by studying adiabatic code deformations on Hamiltonians based on topological codes, notably Kitaev's surface codes and the more recently discovered color codes. We develop protocols that enable universal quantum computing by adiabatic evolution in a way that keeps the energy gap of the system constant with respect to the computation size and introduces only simple local Hamiltonian interactions. This allows one to perform holonomic quantum computing with these topological quantum computing systems. The tools we develop allow one to go beyond numerical simulations and understand these processes analytically.

  15. Quantum information and computation

    SciTech Connect

    Bennett, C.H.

    1995-10-01

    A new quantum theory of communication and computation is emerging, in which the stuff transmitted or processed is not classical information, but arbitrary superpositions of quantum states. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}.

  16. Quantum Computing since Democritus

    NASA Astrophysics Data System (ADS)

    Aaronson, Scott

    2013-03-01

    1. Atoms and the void; 2. Sets; 3. Gödel, Turing, and friends; 4. Minds and machines; 5. Paleocomplexity; 6. P, NP, and friends; 7. Randomness; 8. Crypto; 9. Quantum; 10. Quantum computing; 11. Penrose; 12. Decoherence and hidden variables; 13. Proofs; 14. How big are quantum states?; 15. Skepticism of quantum computing; 16. Learning; 17. Interactive proofs and more; 18. Fun with the Anthropic Principle; 19. Free will; 20. Time travel; 21. Cosmology and complexity; 22. Ask me anything.

  17. Photonic Quantum Computing

    NASA Astrophysics Data System (ADS)

    Barz, Stefanie

    2013-05-01

    Quantum physics has revolutionized our understanding of information processing and enables computational speed-ups that are unattainable using classical computers. In this talk I will present a series of experiments in the field of photonic quantum computing. The first experiment is in the field of photonic state engineering and realizes the generation of heralded polarization-entangled photon pairs. It overcomes the limited applicability of photon-based schemes for quantum information processing tasks, which arises from the probabilistic nature of photon generation. The second experiment uses polarization-entangled photonic qubits to implement ``blind quantum computing,'' a new concept in quantum computing. Blind quantum computing enables a nearly-classical client to access the resources of a more computationally-powerful quantum server without divulging the content of the requested computation. Finally, the concept of blind quantum computing is applied to the field of verification. A new method is developed and experimentally demonstrated, which verifies the entangling capabilities of a quantum computer based on a blind Bell test.

  18. Savannah River Site computing architecture

    SciTech Connect

    Not Available

    1991-03-29

    A computing architecture is a framework for making decisions about the implementation of computer technology and the supporting infrastructure. Because of the size, diversity, and amount of resources dedicated to computing at the Savannah River Site (SRS), there must be an overall strategic plan that can be followed by the thousands of site personnel who make decisions daily that directly affect the SRS computing environment and impact the site`s production and business systems. This plan must address the following requirements: There must be SRS-wide standards for procurement or development of computing systems (hardware and software). The site computing organizations must develop systems that end users find easy to use. Systems must be put in place to support the primary function of site information workers. The developers of computer systems must be given tools that automate and speed up the development of information systems and applications based on computer technology. This document describes a proposal for a site-wide computing architecture that addresses the above requirements. In summary, this architecture is standards-based data-driven, and workstation-oriented with larger systems being utilized for the delivery of needed information to users in a client-server relationship.

  19. Savannah River Site computing architecture

    SciTech Connect

    Not Available

    1991-03-29

    A computing architecture is a framework for making decisions about the implementation of computer technology and the supporting infrastructure. Because of the size, diversity, and amount of resources dedicated to computing at the Savannah River Site (SRS), there must be an overall strategic plan that can be followed by the thousands of site personnel who make decisions daily that directly affect the SRS computing environment and impact the site's production and business systems. This plan must address the following requirements: There must be SRS-wide standards for procurement or development of computing systems (hardware and software). The site computing organizations must develop systems that end users find easy to use. Systems must be put in place to support the primary function of site information workers. The developers of computer systems must be given tools that automate and speed up the development of information systems and applications based on computer technology. This document describes a proposal for a site-wide computing architecture that addresses the above requirements. In summary, this architecture is standards-based data-driven, and workstation-oriented with larger systems being utilized for the delivery of needed information to users in a client-server relationship.

  20. Dissipative quantum computing with open quantum walks

    SciTech Connect

    Sinayskiy, Ilya; Petruccione, Francesco

    2014-12-04

    An open quantum walk approach to the implementation of a dissipative quantum computing scheme is presented. The formalism is demonstrated for the example of an open quantum walk implementation of a 3 qubit quantum circuit consisting of 10 gates.

  1. Probabilistic Cloning and Quantum Computation

    NASA Astrophysics Data System (ADS)

    Gao, Ting; Yan, Feng-Li; Wang, Zhi-Xi

    2004-06-01

    We discuss the usefulness of quantum cloning and present examples of quantum computation tasks for which the cloning offers an advantage which cannot be matched by any approach that does not resort to quantum cloning. In these quantum computations, we need to distribute quantum information contained in the states about which we have some partial information. To perform quantum computations, we use a state-dependent probabilistic quantum cloning procedure to distribute quantum information in the middle of a quantum computation.

  2. Reliability/redundancy trade-off evaluation for multiplexed architectures used to implement quantum dot based computing

    SciTech Connect

    Bhaduri, D.; Shukla, S. K.; Graham, P. S.; Gokhale, M.

    2004-01-01

    With the advent of nanocomputing, researchers have proposed Quantum Dot Cellular Automata (QCA) as one of the implementation technologies. The majority gate is one of the fundamental gates implementable with QCAs. Moreover, majority gates play an important role in defect-tolerant circuit implementations for nanotechnologies due to their use in redundancy mechanisms such as TMR, CTMR etc. Therefore, providing reliable implementation of majority logic using some redundancy mechanism is extremely important. This problem was addressed by von Neumann in 1956, in the form of 'majority multiplexing' and since then several analytical probabilistic models have been proposed to analyze majority multiplexing circuits. However, such analytical approaches are extremely challenging combinatorially and error prone. Also the previous analyses did not distinguish between permanent faults at the gates and transient faults due to noisy interconnects or noise effects on gates. In this paper, we provide explicit fault models for transient and permanent errors at the gates and noise effects at the interconnects. We model majority multiplexing in a probabilistic system description language, and use probabilistic model checking to analyze the effects of our fault models on the different reliability/redundancy trade-offs for majority multiplexing configurations. We also draw parallels with another fundamental logic gate multiplexing technique, namely NAND multiplexing. Tools and methodologies for analyzing redundant architectures that use majority gates will help logic designers to quickly evaluate the amount of redundancy needed to achieve a given level of reliability. VLSI designs at the nanoscale will utilize implementation fabrics prone to faults of permanent and transient nature, and the interconnects will be extensively affected by noise, hence the need for tools that can capture probabilistically quantified fault models and provide quick evaluation of the trade-offs. A comparative

  3. Parallel Architecture For Robotics Computation

    NASA Technical Reports Server (NTRS)

    Fijany, Amir; Bejczy, Antal K.

    1990-01-01

    Universal Real-Time Robotic Controller and Simulator (URRCS) is highly parallel computing architecture for control and simulation of robot motion. Result of extensive algorithmic study of different kinematic and dynamic computational problems arising in control and simulation of robot motion. Study led to development of class of efficient parallel algorithms for these problems. Represents algorithmically specialized architecture, in sense capable of exploiting common properties of this class of parallel algorithms. System with both MIMD and SIMD capabilities. Regarded as processor attached to bus of external host processor, as part of bus memory.

  4. Quantum Analog Computing

    NASA Technical Reports Server (NTRS)

    Zak, M.

    1998-01-01

    Quantum analog computing is based upon similarity between mathematical formalism of quantum mechanics and phenomena to be computed. It exploits a dynamical convergence of several competing phenomena to an attractor which can represent an externum of a function, an image, a solution to a system of ODE, or a stochastic process.

  5. VLSI Architectures for Computing DFT's

    NASA Technical Reports Server (NTRS)

    Truong, T. K.; Chang, J. J.; Hsu, I. S.; Reed, I. S.; Pei, D. Y.

    1986-01-01

    Simplifications result from use of residue Fermat number systems. System of finite arithmetic over residue Fermat number systems enables calculation of discrete Fourier transform (DFT) of series of complex numbers with reduced number of multiplications. Computer architectures based on approach suitable for design of very-large-scale integrated (VLSI) circuits for computing DFT's. General approach not limited to DFT's; Applicable to decoding of error-correcting codes and other transform calculations. System readily implemented in VLSI.

  6. Disciplines, models, and computers: the path to computational quantum chemistry.

    PubMed

    Lenhard, Johannes

    2014-12-01

    Many disciplines and scientific fields have undergone a computational turn in the past several decades. This paper analyzes this sort of turn by investigating the case of computational quantum chemistry. The main claim is that the transformation from quantum to computational quantum chemistry involved changes in three dimensions. First, on the side of instrumentation, small computers and a networked infrastructure took over the lead from centralized mainframe architecture. Second, a new conception of computational modeling became feasible and assumed a crucial role. And third, the field of computa- tional quantum chemistry became organized in a market-like fashion and this market is much bigger than the number of quantum theory experts. These claims will be substantiated by an investigation of the so-called density functional theory (DFT), the arguably pivotal theory in the turn to computational quantum chemistry around 1990. PMID:25571750

  7. Quantum computing with trapped ions

    SciTech Connect

    Hughes, R.J.

    1998-01-01

    The significance of quantum computation for cryptography is discussed. Following a brief survey of the requirements for quantum computational hardware, an overview of the ion trap quantum computation project at Los Alamos is presented. The physical limitations to quantum computation with trapped ions are analyzed and an assessment of the computational potential of the technology is made.

  8. Quantum computation: Honesty test

    NASA Astrophysics Data System (ADS)

    Morimae, Tomoyuki

    2013-11-01

    Alice does not have a quantum computer so she delegates a computation to Bob, who does own one. But how can Alice check whether the computation that Bob performs for her is correct? An experiment with photonic qubits demonstrates such a verification protocol.

  9. Entanglement and adiabatic quantum computation

    NASA Astrophysics Data System (ADS)

    Ahrensmeier, D.

    2006-06-01

    Adiabatic quantum computation provides an alternative approach to quantum computation using a time-dependent Hamiltonian. The time evolution of entanglement during the adiabatic quantum search algorithm is studied, and its relevance as a resource is discussed.

  10. Optimal architectures for long distance quantum communication.

    PubMed

    Muralidharan, Sreraman; Li, Linshu; Kim, Jungsang; Lütkenhaus, Norbert; Lukin, Mikhail D; Jiang, Liang

    2016-01-01

    Despite the tremendous progress of quantum cryptography, efficient quantum communication over long distances (≥ 1000 km) remains an outstanding challenge due to fiber attenuation and operation errors accumulated over the entire communication distance. Quantum repeaters (QRs), as a promising approach, can overcome both photon loss and operation errors, and hence significantly speedup the communication rate. Depending on the methods used to correct loss and operation errors, all the proposed QR schemes can be classified into three categories (generations). Here we present the first systematic comparison of three generations of quantum repeaters by evaluating the cost of both temporal and physical resources, and identify the optimized quantum repeater architecture for a given set of experimental parameters for use in quantum key distribution. Our work provides a roadmap for the experimental realizations of highly efficient quantum networks over transcontinental distances. PMID:26876670

  11. Optimal architectures for long distance quantum communication

    NASA Astrophysics Data System (ADS)

    Muralidharan, Sreraman; Li, Linshu; Kim, Jungsang; Lütkenhaus, Norbert; Lukin, Mikhail D.; Jiang, Liang

    2016-02-01

    Despite the tremendous progress of quantum cryptography, efficient quantum communication over long distances (≥1000 km) remains an outstanding challenge due to fiber attenuation and operation errors accumulated over the entire communication distance. Quantum repeaters (QRs), as a promising approach, can overcome both photon loss and operation errors, and hence significantly speedup the communication rate. Depending on the methods used to correct loss and operation errors, all the proposed QR schemes can be classified into three categories (generations). Here we present the first systematic comparison of three generations of quantum repeaters by evaluating the cost of both temporal and physical resources, and identify the optimized quantum repeater architecture for a given set of experimental parameters for use in quantum key distribution. Our work provides a roadmap for the experimental realizations of highly efficient quantum networks over transcontinental distances.

  12. Optimal architectures for long distance quantum communication

    PubMed Central

    Muralidharan, Sreraman; Li, Linshu; Kim, Jungsang; Lütkenhaus, Norbert; Lukin, Mikhail D.; Jiang, Liang

    2016-01-01

    Despite the tremendous progress of quantum cryptography, efficient quantum communication over long distances (≥1000 km) remains an outstanding challenge due to fiber attenuation and operation errors accumulated over the entire communication distance. Quantum repeaters (QRs), as a promising approach, can overcome both photon loss and operation errors, and hence significantly speedup the communication rate. Depending on the methods used to correct loss and operation errors, all the proposed QR schemes can be classified into three categories (generations). Here we present the first systematic comparison of three generations of quantum repeaters by evaluating the cost of both temporal and physical resources, and identify the optimized quantum repeater architecture for a given set of experimental parameters for use in quantum key distribution. Our work provides a roadmap for the experimental realizations of highly efficient quantum networks over transcontinental distances. PMID:26876670

  13. Verifiable Quantum Computing

    NASA Astrophysics Data System (ADS)

    Kashefi, Elham

    Over the next five to ten years we will see a state of flux as quantum devices become part of the mainstream computing landscape. However adopting and applying such a highly variable and novel technology is both costly and risky as this quantum approach has an acute verification and validation problem: On the one hand, since classical computations cannot scale up to the computational power of quantum mechanics, verifying the correctness of a quantum-mediated computation is challenging; on the other hand, the underlying quantum structure resists classical certification analysis. Our grand aim is to settle these key milestones to make the translation from theory to practice possible. Currently the most efficient ways to verify a quantum computation is to employ cryptographic methods. I will present the current state of the art of various existing protocols where generally there exists a trade-off between the practicality of the scheme versus their generality, trust assumptions and security level. EK gratefully acknowledges funding through EPSRC Grants EP/N003829/1 and EP/M013243/1.

  14. One-way quantum computation with circuit quantum electrodynamics

    SciTech Connect

    Wu Chunwang; Han Yang; Chen Pingxing; Li Chengzu; Zhong Xiaojun

    2010-03-15

    In this Brief Report, we propose a potential scheme to implement one-way quantum computation with circuit quantum electrodynamics (QED). Large cluster states of charge qubits can be generated in just one step with a superconducting transmission line resonator (TLR) playing the role of a dispersive coupler. A single-qubit measurement in the arbitrary basis can be implemented using a single electron transistor with the help of one-qubit gates. By examining the main decoherence sources, we show that circuit QED is a promising architecture for one-way quantum computation.

  15. Quantum Computing using Photons

    NASA Astrophysics Data System (ADS)

    Elhalawany, Ahmed; Leuenberger, Michael

    2013-03-01

    In this work, we propose a theoretical model of two-quantum bit gates for quantum computation using the polarization states of two photons in a microcavity. By letting the two photons interact non-resonantly with four quantum dots inside the cavity, we obtain an effective photon-photon interaction which we exploit for the implementation of an universal XOR gate. The two-photon Hamiltonian is written in terms of the photons' total angular momentum operators and their states are written using the Schwinger representation of the total angular momentum.

  16. Computational quantum chemistry website

    SciTech Connect

    1997-08-22

    This report contains the contents of a web page related to research on the development of quantum chemistry methods for computational thermochemistry and the application of quantum chemistry methods to problems in material chemistry and chemical sciences. Research programs highlighted include: Gaussian-2 theory; Density functional theory; Molecular sieve materials; Diamond thin-film growth from buckyball precursors; Electronic structure calculations on lithium polymer electrolytes; Long-distance electronic coupling in donor/acceptor molecules; and Computational studies of NOx reactions in radioactive waste storage.

  17. The flight telerobotic servicer: From functional architecture to computer architecture

    NASA Technical Reports Server (NTRS)

    Lumia, Ronald; Fiala, John

    1989-01-01

    After a brief tutorial on the NASA/National Bureau of Standards Standard Reference Model for Telerobot Control System Architecture (NASREM) functional architecture, the approach to its implementation is shown. First, interfaces must be defined which are capable of supporting the known algorithms. This is illustrated by considering the interfaces required for the SERVO level of the NASREM functional architecture. After interface definition, the specific computer architecture for the implementation must be determined. This choice is obviously technology dependent. An example illustrating one possible mapping of the NASREM functional architecture to a particular set of computers which implements it is shown. The result of choosing the NASREM functional architecture is that it provides a technology independent paradigm which can be mapped into a technology dependent implementation capable of evolving with technology in the laboratory and in space.

  18. Cavity-based architecture to preserve quantum coherence and entanglement

    PubMed Central

    Man, Zhong-Xiao; Xia, Yun-Jie; Lo Franco, Rosario

    2015-01-01

    Quantum technology relies on the utilization of resources, like quantum coherence and entanglement, which allow quantum information and computation processing. This achievement is however jeopardized by the detrimental effects of the environment surrounding any quantum system, so that finding strategies to protect quantum resources is essential. Non-Markovian and structured environments are useful tools to this aim. Here we show how a simple environmental architecture made of two coupled lossy cavities enables a switch between Markovian and non-Markovian regimes for the dynamics of a qubit embedded in one of the cavity. Furthermore, qubit coherence can be indefinitely preserved if the cavity without qubit is perfect. We then focus on entanglement control of two independent qubits locally subject to such an engineered environment and discuss its feasibility in the framework of circuit quantum electrodynamics. With up-to-date experimental parameters, we show that our architecture allows entanglement lifetimes orders of magnitude longer than the spontaneous lifetime without local cavity couplings. This cavity-based architecture is straightforwardly extendable to many qubits for scalability. PMID:26351004

  19. Cavity-based architecture to preserve quantum coherence and entanglement.

    PubMed

    Man, Zhong-Xiao; Xia, Yun-Jie; Lo Franco, Rosario

    2015-01-01

    Quantum technology relies on the utilization of resources, like quantum coherence and entanglement, which allow quantum information and computation processing. This achievement is however jeopardized by the detrimental effects of the environment surrounding any quantum system, so that finding strategies to protect quantum resources is essential. Non-Markovian and structured environments are useful tools to this aim. Here we show how a simple environmental architecture made of two coupled lossy cavities enables a switch between Markovian and non-Markovian regimes for the dynamics of a qubit embedded in one of the cavity. Furthermore, qubit coherence can be indefinitely preserved if the cavity without qubit is perfect. We then focus on entanglement control of two independent qubits locally subject to such an engineered environment and discuss its feasibility in the framework of circuit quantum electrodynamics. With up-to-date experimental parameters, we show that our architecture allows entanglement lifetimes orders of magnitude longer than the spontaneous lifetime without local cavity couplings. This cavity-based architecture is straightforwardly extendable to many qubits for scalability. PMID:26351004

  20. Undergraduate computational physics projects on quantum computing

    NASA Astrophysics Data System (ADS)

    Candela, D.

    2015-08-01

    Computational projects on quantum computing suitable for students in a junior-level quantum mechanics course are described. In these projects students write their own programs to simulate quantum computers. Knowledge is assumed of introductory quantum mechanics through the properties of spin 1/2. Initial, more easily programmed projects treat the basics of quantum computation, quantum gates, and Grover's quantum search algorithm. These are followed by more advanced projects to increase the number of qubits and implement Shor's quantum factoring algorithm. The projects can be run on a typical laptop or desktop computer, using most programming languages. Supplementing resources available elsewhere, the projects are presented here in a self-contained format especially suitable for a short computational module for physics students.

  1. Hybrid quantum computing: semicloning for general database retrieval

    NASA Astrophysics Data System (ADS)

    Lanzagorta, Marco; Uhlmann, Jeffrey K.

    2005-05-01

    Quantum computing (QC) has become an important area of research in computer science because of its potential to provide more efficient algorithmic solutions to certain problems than are possible with classical computing (CC). In particular, QC is able to exploit the special properties of quantum superposition to achieve computational parallelism beyond what can be achieved with parallel CC computers. However, these special properties are not applicable for general computation. Therefore, we propose the use of "hybrid quantum computers" (HQCs) that combine both classical and quantum computing architectures in order to leverage the benefits of both. We demonstrate how an HQC can exploit quantum search to support general database operations more efficiently than is possible with CC. Our solution is based on new quantum results that are of independent significance to the field of quantum computing. More specifically, we demonstrate that the most restrictive implications of the quantum No-Cloning Theorem can be avoided through the use of semiclones.

  2. Quantum architecture of novel solids

    NASA Astrophysics Data System (ADS)

    Zunger, A.

    2001-01-01

    The current status of our understanding of Quantum Mechanics is that if one specifies the chemical formula of a compound (e.g., CuAu, or GaAs, or NiPt) it is still impossible to predict if this material is a superconductor or not, but it is now possible to predict its crystal structure. This is a nontrivial accomplishment for there are as many as 2N possible structures for a binary compound. This article reviews this classic question of structural chemistry and condensed matter physics: How can one figure out which of the astronomic number of possible crystal structures is selected by Nature?

  3. Quantum computers: Definition and implementations

    SciTech Connect

    Perez-Delgado, Carlos A.; Kok, Pieter

    2011-01-15

    The DiVincenzo criteria for implementing a quantum computer have been seminal in focusing both experimental and theoretical research in quantum-information processing. These criteria were formulated specifically for the circuit model of quantum computing. However, several new models for quantum computing (paradigms) have been proposed that do not seem to fit the criteria well. Therefore, the question is what are the general criteria for implementing quantum computers. To this end, a formal operational definition of a quantum computer is introduced. It is then shown that, according to this definition, a device is a quantum computer if it obeys the following criteria: Any quantum computer must consist of a quantum memory, with an additional structure that (1) facilitates a controlled quantum evolution of the quantum memory; (2) includes a method for information theoretic cooling of the memory; and (3) provides a readout mechanism for subsets of the quantum memory. The criteria are met when the device is scalable and operates fault tolerantly. We discuss various existing quantum computing paradigms and how they fit within this framework. Finally, we present a decision tree for selecting an avenue toward building a quantum computer. This is intended to help experimentalists determine the most natural paradigm given a particular physical implementation.

  4. Quantum computers: Definition and implementations

    NASA Astrophysics Data System (ADS)

    Pérez-Delgado, Carlos A.; Kok, Pieter

    2011-01-01

    The DiVincenzo criteria for implementing a quantum computer have been seminal in focusing both experimental and theoretical research in quantum-information processing. These criteria were formulated specifically for the circuit model of quantum computing. However, several new models for quantum computing (paradigms) have been proposed that do not seem to fit the criteria well. Therefore, the question is what are the general criteria for implementing quantum computers. To this end, a formal operational definition of a quantum computer is introduced. It is then shown that, according to this definition, a device is a quantum computer if it obeys the following criteria: Any quantum computer must consist of a quantum memory, with an additional structure that (1) facilitates a controlled quantum evolution of the quantum memory; (2) includes a method for information theoretic cooling of the memory; and (3) provides a readout mechanism for subsets of the quantum memory. The criteria are met when the device is scalable and operates fault tolerantly. We discuss various existing quantum computing paradigms and how they fit within this framework. Finally, we present a decision tree for selecting an avenue toward building a quantum computer. This is intended to help experimentalists determine the most natural paradigm given a particular physical implementation.

  5. Brain architecture: a design for natural computation.

    PubMed

    Kaiser, Marcus

    2007-12-15

    Fifty years ago, John von Neumann compared the architecture of the brain with that of the computers he invented and which are still in use today. In those days, the organization of computers was based on concepts of brain organization. Here, we give an update on current results on the global organization of neural systems. For neural systems, we outline how the spatial and topological architecture of neuronal and cortical networks facilitates robustness against failures, fast processing and balanced network activation. Finally, we discuss mechanisms of self-organization for such architectures. After all, the organization of the brain might again inspire computer architecture. PMID:17855223

  6. Quantum-cellular-automata quantum computing with endohedral fullerenes

    NASA Astrophysics Data System (ADS)

    Twamley, J.

    2003-05-01

    We present a scheme to perform universal quantum computation using global addressing techniques as applied to a physical system of endohedrally doped fullerenes. The system consists of an ABAB linear array of group-V endohedrally doped fullerenes. Each molecule spin site consists of a nuclear spin coupled via a hyperfine interaction to an electron spin. The electron spin of each molecule is in a quartet ground state S=3/2. Neighboring molecular electron spins are coupled via a magnetic dipole interaction. We find that an all-electron construction of a quantum cellular automaton is frustrated due to the degeneracy of the electronic transitions. However, we can construct a quantum-cellular-automata quantum computing architecture using these molecules by encoding the quantum information on the nuclear spins while using the electron spins as a local bus. We deduce the NMR and ESR pulses required to execute the basic cellular automaton operation and obtain a rough figure of merit for the number of gate operations per decoherence time. We find that this figure of merit compares well with other physical quantum computer proposals. We argue that the proposed architecture meets well the first four DiVincenzo criteria and we outline various routes toward meeting the fifth criterion: qubit readout.

  7. A surface code quantum computer in silicon.

    PubMed

    Hill, Charles D; Peretz, Eldad; Hile, Samuel J; House, Matthew G; Fuechsle, Martin; Rogge, Sven; Simmons, Michelle Y; Hollenberg, Lloyd C L

    2015-10-01

    The exceptionally long quantum coherence times of phosphorus donor nuclear spin qubits in silicon, coupled with the proven scalability of silicon-based nano-electronics, make them attractive candidates for large-scale quantum computing. However, the high threshold of topological quantum error correction can only be captured in a two-dimensional array of qubits operating synchronously and in parallel-posing formidable fabrication and control challenges. We present an architecture that addresses these problems through a novel shared-control paradigm that is particularly suited to the natural uniformity of the phosphorus donor nuclear spin qubit states and electronic confinement. The architecture comprises a two-dimensional lattice of donor qubits sandwiched between two vertically separated control layers forming a mutually perpendicular crisscross gate array. Shared-control lines facilitate loading/unloading of single electrons to specific donors, thereby activating multiple qubits in parallel across the array on which the required operations for surface code quantum error correction are carried out by global spin control. The complexities of independent qubit control, wave function engineering, and ad hoc quantum interconnects are explicitly avoided. With many of the basic elements of fabrication and control based on demonstrated techniques and with simulated quantum operation below the surface code error threshold, the architecture represents a new pathway for large-scale quantum information processing in silicon and potentially in other qubit systems where uniformity can be exploited. PMID:26601310

  8. A surface code quantum computer in silicon

    PubMed Central

    Hill, Charles D.; Peretz, Eldad; Hile, Samuel J.; House, Matthew G.; Fuechsle, Martin; Rogge, Sven; Simmons, Michelle Y.; Hollenberg, Lloyd C. L.

    2015-01-01

    The exceptionally long quantum coherence times of phosphorus donor nuclear spin qubits in silicon, coupled with the proven scalability of silicon-based nano-electronics, make them attractive candidates for large-scale quantum computing. However, the high threshold of topological quantum error correction can only be captured in a two-dimensional array of qubits operating synchronously and in parallel—posing formidable fabrication and control challenges. We present an architecture that addresses these problems through a novel shared-control paradigm that is particularly suited to the natural uniformity of the phosphorus donor nuclear spin qubit states and electronic confinement. The architecture comprises a two-dimensional lattice of donor qubits sandwiched between two vertically separated control layers forming a mutually perpendicular crisscross gate array. Shared-control lines facilitate loading/unloading of single electrons to specific donors, thereby activating multiple qubits in parallel across the array on which the required operations for surface code quantum error correction are carried out by global spin control. The complexities of independent qubit control, wave function engineering, and ad hoc quantum interconnects are explicitly avoided. With many of the basic elements of fabrication and control based on demonstrated techniques and with simulated quantum operation below the surface code error threshold, the architecture represents a new pathway for large-scale quantum information processing in silicon and potentially in other qubit systems where uniformity can be exploited. PMID:26601310

  9. Computational Biology, Advanced Scientific Computing, and Emerging Computational Architectures

    SciTech Connect

    2007-06-27

    This CRADA was established at the start of FY02 with $200 K from IBM and matching funds from DOE to support post-doctoral fellows in collaborative research between International Business Machines and Oak Ridge National Laboratory to explore effective use of emerging petascale computational architectures for the solution of computational biology problems. 'No cost' extensions of the CRADA were negotiated with IBM for FY03 and FY04.

  10. Quantum computing on encrypted data

    NASA Astrophysics Data System (ADS)

    Fisher, K. A. G.; Broadbent, A.; Shalm, L. K.; Yan, Z.; Lavoie, J.; Prevedel, R.; Jennewein, T.; Resch, K. J.

    2014-01-01

    The ability to perform computations on encrypted data is a powerful tool for protecting privacy. Recently, protocols to achieve this on classical computing systems have been found. Here, we present an efficient solution to the quantum analogue of this problem that enables arbitrary quantum computations to be carried out on encrypted quantum data. We prove that an untrusted server can implement a universal set of quantum gates on encrypted quantum bits (qubits) without learning any information about the inputs, while the client, knowing the decryption key, can easily decrypt the results of the computation. We experimentally demonstrate, using single photons and linear optics, the encryption and decryption scheme on a set of gates sufficient for arbitrary quantum computations. As our protocol requires few extra resources compared with other schemes it can be easily incorporated into the design of future quantum servers. These results will play a key role in enabling the development of secure distributed quantum systems.

  11. Quantum computing on encrypted data.

    PubMed

    Fisher, K A G; Broadbent, A; Shalm, L K; Yan, Z; Lavoie, J; Prevedel, R; Jennewein, T; Resch, K J

    2014-01-01

    The ability to perform computations on encrypted data is a powerful tool for protecting privacy. Recently, protocols to achieve this on classical computing systems have been found. Here, we present an efficient solution to the quantum analogue of this problem that enables arbitrary quantum computations to be carried out on encrypted quantum data. We prove that an untrusted server can implement a universal set of quantum gates on encrypted quantum bits (qubits) without learning any information about the inputs, while the client, knowing the decryption key, can easily decrypt the results of the computation. We experimentally demonstrate, using single photons and linear optics, the encryption and decryption scheme on a set of gates sufficient for arbitrary quantum computations. As our protocol requires few extra resources compared with other schemes it can be easily incorporated into the design of future quantum servers. These results will play a key role in enabling the development of secure distributed quantum systems. PMID:24445949

  12. Quantum Computing's Classical Problem, Classical Computing's Quantum Problem

    NASA Astrophysics Data System (ADS)

    Van Meter, Rodney

    2014-08-01

    Tasked with the challenge to build better and better computers, quantum computing and classical computing face the same conundrum: the success of classical computing systems. Small quantum computing systems have been demonstrated, and intermediate-scale systems are on the horizon, capable of calculating numeric results or simulating physical systems far beyond what humans can do by hand. However, to be commercially viable, they must surpass what our wildly successful, highly advanced classical computers can already do. At the same time, those classical computers continue to advance, but those advances are now constrained by thermodynamics, and will soon be limited by the discrete nature of atomic matter and ultimately quantum effects. Technological advances benefit both quantum and classical machinery, altering the competitive landscape. Can we build quantum computing systems that out-compute classical systems capable of some logic gates per month? This article will discuss the interplay in these competing and cooperating technological trends.

  13. Quantum computing with defects.

    PubMed

    Weber, J R; Koehl, W F; Varley, J B; Janotti, A; Buckley, B B; Van de Walle, C G; Awschalom, D D

    2010-05-11

    Identifying and designing physical systems for use as qubits, the basic units of quantum information, are critical steps in the development of a quantum computer. Among the possibilities in the solid state, a defect in diamond known as the nitrogen-vacancy (NV(-1)) center stands out for its robustness--its quantum state can be initialized, manipulated, and measured with high fidelity at room temperature. Here we describe how to systematically identify other deep center defects with similar quantum-mechanical properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate defect systems. To illustrate these points in detail, we compare electronic structure calculations of the NV(-1) center in diamond with those of several deep centers in 4H silicon carbide (SiC). We then discuss the proposed criteria for similar defects in other tetrahedrally coordinated semiconductors. PMID:20404195

  14. Silicon enhancement mode nanostructures for quantum computing.

    SciTech Connect

    Carroll, Malcolm S.

    2010-03-01

    Development of silicon, enhancement mode nanostructures for solid-state quantum computing will be described. A primary motivation of this research is the recent unprecedented manipulation of single electron spins in GaAs quantum dots, which has been used to demonstrate a quantum bit. Long spin decoherence times are predicted possible in silicon qubits. This talk will focus on silicon enhancement mode quantum dot structures that emulate the GaAs lateral quantum dot qubit but use an enhancement mode field effect transistor (FET) structure. One critical concern for silicon quantum dots that use oxides as insulators in the FET structure is that defects in the metal oxide semiconductor (MOS) stack can produce both detrimental electrostatic and paramagnetic effects on the qubit. Understanding the implications of defects in the Si MOS system is also relevant for other qubit architectures that have nearby dielectric passivated surfaces. Stable, lithographically defined, single-period Coulomb-blockade and single-electron charge sensing in a quantum dot nanostructure using a MOS stack will be presented. A combination of characterization of defects, modeling and consideration of modified approaches that incorporate SiGe or donors provides guidance about the enhancement mode MOS approach for future qubits and quantum circuit micro-architecture.

  15. Teaching Computer Aided Architectural Design at UCLA.

    ERIC Educational Resources Information Center

    Mitchell, William J.

    This brief overview includes a rationale for the program and describes course goals and objectives, curriculum content, teaching methods and materials, staffing, and problems of integrating computer aided design with traditional architectural curricula at the School of Architecture and Urban Planning at UCLA. A list of texts for use in teaching…

  16. Semiconductor-inspired superconducting quantum computing

    NASA Astrophysics Data System (ADS)

    Shim, Yun-Pil

    Superconducting circuits offer tremendous design flexibility in the quantum regime culminating most recently in the demonstration of few qubit systems supposedly approaching the threshold for fault-tolerant quantum information processing. Competition in the solid-state comes from semiconductor qubits, where nature has bestowed some very useful properties which can be utilized for spin qubit based quantum computing. Here we present an architecture for superconducting quantum computing based on selective design principles deduced from spin-based systems. We propose an encoded qubit approach realizable with state-of-the-art tunable Josephson junction qubits. Our results show that this design philosophy holds promise, enables microwave-free control, and offers a pathway to future qubit designs with new capabilities such as with higher fidelity or, perhaps, operation at higher temperature. The approach is especially suited to qubits based on variable super-semi junctions.

  17. Universal quantum computation by discontinuous quantum walk

    SciTech Connect

    Underwood, Michael S.; Feder, David L.

    2010-10-15

    Quantum walks are the quantum-mechanical analog of random walks, in which a quantum ''walker'' evolves between initial and final states by traversing the edges of a graph, either in discrete steps from node to node or via continuous evolution under the Hamiltonian furnished by the adjacency matrix of the graph. We present a hybrid scheme for universal quantum computation in which a quantum walker takes discrete steps of continuous evolution. This ''discontinuous'' quantum walk employs perfect quantum-state transfer between two nodes of specific subgraphs chosen to implement a universal gate set, thereby ensuring unitary evolution without requiring the introduction of an ancillary coin space. The run time is linear in the number of simulated qubits and gates. The scheme allows multiple runs of the algorithm to be executed almost simultaneously by starting walkers one time step apart.

  18. A scalable quantum architecture using efficient non-local gates

    NASA Astrophysics Data System (ADS)

    Brennen, Gavin

    2003-03-01

    Many protocols for quantum information processing use a control sequence or circuit of interactions between qubits and control fields wherein arbitrary qubits can be made to interact with one another. The primary problem with many ``physically scalable" architectures is that the qubits are restricted to nearest neighbor interactions and quantum wires between distant qubits do not exist. Because of errors, nearest neighbor interactions often present difficulty with scalability. We describe a protocol that efficiently performs non-local gates between elements of separated static logical qubits using a bus of dynamic qubits as a refreshable entanglement resource. Imperfect resource preparation due to error propagation from noisy gates and measurement errors can purified within the bus channel. Because of the inherent parallelism of entanglement swapping, communication latency within the quantum computer can be significantly reduced.

  19. Communication Capacity of Quantum Computation

    NASA Astrophysics Data System (ADS)

    Bose, S.; Rallan, L.; Vedral, V.

    2000-12-01

    By considering quantum computation as a communication process, we relate its efficiency to its classical communication capacity. This formalism allows us to derive lower bounds on the complexity of search algorithms in the most general context. It enables us to link the mixedness of a quantum computer to its efficiency and also allows us to derive the critical level of mixedness beyond which there is no quantum advantage in computation.

  20. Algorithms Bridging Quantum Computation and Chemistry

    NASA Astrophysics Data System (ADS)

    McClean, Jarrod Ryan

    The design of new materials and chemicals derived entirely from computation has long been a goal of computational chemistry, and the governing equation whose solution would permit this dream is known. Unfortunately, the exact solution to this equation has been far too expensive and clever approximations fail in critical situations. Quantum computers offer a novel solution to this problem. In this work, we develop not only new algorithms to use quantum computers to study hard problems in chemistry, but also explore how such algorithms can help us to better understand and improve our traditional approaches. In particular, we first introduce a new method, the variational quantum eigensolver, which is designed to maximally utilize the quantum resources available in a device to solve chemical problems. We apply this method in a real quantum photonic device in the lab to study the dissociation of the helium hydride (HeH+) molecule. We also enhance this methodology with architecture specific optimizations on ion trap computers and show how linear-scaling techniques from traditional quantum chemistry can be used to improve the outlook of similar algorithms on quantum computers. We then show how studying quantum algorithms such as these can be used to understand and enhance the development of classical algorithms. In particular we use a tool from adiabatic quantum computation, Feynman's Clock, to develop a new discrete time variational principle and further establish a connection between real-time quantum dynamics and ground state eigenvalue problems. We use these tools to develop two novel parallel-in-time quantum algorithms that outperform competitive algorithms as well as offer new insights into the connection between the fermion sign problem of ground states and the dynamical sign problem of quantum dynamics. Finally we use insights gained in the study of quantum circuits to explore a general notion of sparsity in many-body quantum systems. In particular we use

  1. Towards Quantum Computing With Light

    NASA Astrophysics Data System (ADS)

    Pysher, Matthew

    This thesis presents experimental progress towards the realization of an optical quantum computer. Quantum computers replace the bits used in classical computing with quantum systems and promise an exponential speedup over their classical counterparts for certain tasks such as integer factoring and the simulation of quantum systems. A recently proposed quantum computing protocol known as one-way quantum computing has paved the way for the use of light in a functional quantum computer. One-way quantum computing calls for the generation of a large (consisting of many subsystems) entangled state known as a cluster state to serve as a quantum register. Entangled states are comprised of subsystems linked in such a way that the state cannot be separated into individual components. A recent proposal has shown that is possible to make arbitrarily large cluster states by linking the resonant frequency modes of a single optical parametric oscillator (OPO). In this thesis, we present two major steps towards the creation of such a cluster state. Namely, we successfully design and test the exotic nonlinear crystal needed in this proposal and use a slight variation on this proposal to simultaneously create over 15 four-mode cluster states in a single OPO. We also explore the possibility of scaling down the physical size of an optical quantum computer by generating squeezed states of light in a compact optical waveguide. Additionally, we investigate photon-number-resolving measurements on continuous quantum light sources, which will be necessary to obtain the desired speedups for a quantum computer over a classical computer.

  2. A computer architecture for intelligent machines

    NASA Technical Reports Server (NTRS)

    Lefebvre, D. R.; Saridis, G. N.

    1991-01-01

    The Theory of Intelligent Machines proposes a hierarchical organization for the functions of an autonomous robot based on the Principle of Increasing Precision With Decreasing Intelligence. An analytic formulation of this theory using information-theoretic measures of uncertainty for each level of the intelligent machine has been developed in recent years. A computer architecture that implements the lower two levels of the intelligent machine is presented. The architecture supports an event-driven programming paradigm that is independent of the underlying computer architecture and operating system. Details of Execution Level controllers for motion and vision systems are addressed, as well as the Petri net transducer software used to implement Coordination Level functions. Extensions to UNIX and VxWorks operating systems which enable the development of a heterogeneous, distributed application are described. A case study illustrates how this computer architecture integrates real-time and higher-level control of manipulator and vision systems.

  3. A computer architecture for intelligent machines

    NASA Technical Reports Server (NTRS)

    Lefebvre, D. R.; Saridis, G. N.

    1992-01-01

    The theory of intelligent machines proposes a hierarchical organization for the functions of an autonomous robot based on the principle of increasing precision with decreasing intelligence. An analytic formulation of this theory using information-theoretic measures of uncertainty for each level of the intelligent machine has been developed. The authors present a computer architecture that implements the lower two levels of the intelligent machine. The architecture supports an event-driven programming paradigm that is independent of the underlying computer architecture and operating system. Execution-level controllers for motion and vision systems are briefly addressed, as well as the Petri net transducer software used to implement coordination-level functions. A case study illustrates how this computer architecture integrates real-time and higher-level control of manipulator and vision systems.

  4. Quantum Nash Equilibria and Quantum Computing

    NASA Astrophysics Data System (ADS)

    Fellman, Philip Vos; Post, Jonathan Vos

    In 2004, At the Fifth International Conference on Complex Systems, we drew attention to some remarkable findings by researchers at the Santa Fe Institute (Sato, Farmer and Akiyama, 2001) about hitherto unsuspected complexity in the Nash Equilibrium. As we progressed from these findings about heteroclinic Hamiltonians and chaotic transients hidden within the learning patterns of the simple rock-paper-scissors game to some related findings on the theory of quantum computing, one of the arguments we put forward was just as in the late 1990's a number of new Nash equilibria were discovered in simple bi-matrix games (Shubik and Quint, 1996; Von Stengel, 1997, 2000; and McLennan and Park, 1999) we would begin to see new Nash equilibria discovered as the result of quantum computation. While actual quantum computers remain rather primitive (Toibman, 2004), and the theory of quantum computation seems to be advancing perhaps a bit more slowly than originally expected, there have, nonetheless, been a number of advances in computation and some more radical advances in an allied field, quantum game theory (Huberman and Hogg, 2004) which are quite significant. In the course of this paper we will review a few of these discoveries and illustrate some of the characteristics of these new "Quantum Nash Equilibria". The full text of this research can be found at http://necsi.org/events/iccs6/viewpaper.php?id-234

  5. Quantum computing with defects

    NASA Astrophysics Data System (ADS)

    Varley, Joel

    2011-03-01

    The development of a quantum computer is contingent upon the identification and design of systems for use as qubits, the basic units of quantum information. One of the most promising candidates consists of a defect in diamond known as the nitrogen-vacancy (NV-1) center, since it is an individually-addressable quantum system that can be initialized, manipulated, and measured with high fidelity at room temperature. While the success of the NV-1 stems from its nature as a localized ``deep-center'' point defect, no systematic effort has been made to identify other defects that might behave in a similar way. We provide guidelines for identifying other defect centers with similar properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate systems. To elucidate these points, we compare electronic structure calculations of the NV-1 center in diamond with those of several deep centers in 4H silicon carbide (SiC). Using hybrid functionals, we report formation energies, configuration-coordinate diagrams, and defect-level diagrams to compare and contrast the properties of these defects. We find that the NC VSi - 1 center in SiC, a structural analog of the NV-1 center in diamond, may be a suitable center with very different optical transition energies. We also discuss how the proposed criteria can be translated into guidelines to discover NV analogs in other tetrahedrally coordinated materials. This work was performed in collaboration with J. R. Weber, W. F. Koehl, B. B. Buckley, A. Janotti, C. G. Van de Walle, and D. D. Awschalom. This work was supported by ARO, AFOSR, and NSF.

  6. Quantum Computing: Solving Complex Problems

    ScienceCinema

    DiVincenzo, David [IBM Watson Research Center

    2009-09-01

    One of the motivating ideas of quantum computation was that there could be a new kind of machine that would solve hard problems in quantum mechanics. There has been significant progress towards the experimental realization of these machines (which I will review), but there are still many questions about how such a machine could solve computational problems of interest in quantum physics. New categorizations of the complexity of computational problems have now been invented to describe quantum simulation. The bad news is that some of these problems are believed to be intractable even on a quantum computer, falling into a quantum analog of the NP class. The good news is that there are many other new classifications of tractability that may apply to several situations of physical interest.

  7. Quantum Computing: Solving Complex Problems

    SciTech Connect

    DiVincenzo, David

    2007-04-12

    One of the motivating ideas of quantum computation was that there could be a new kind of machine that would solve hard problems in quantum mechanics. There has been significant progress towards the experimental realization of these machines (which I will review), but there are still many questions about how such a machine could solve computational problems of interest in quantum physics. New categorizations of the complexity of computational problems have now been invented to describe quantum simulation. The bad news is that some of these problems are believed to be intractable even on a quantum computer, falling into a quantum analog of the NP class. The good news is that there are many other new classifications of tractability that may apply to several situations of physical interest.

  8. Quantum Computing: Solving Complex Problems

    SciTech Connect

    DiVincenzo, David

    2007-04-11

    One of the motivating ideas of quantum computation was that there could be a new kind of machine that would solve hard problems in quantum mechanics. There has been significant progress towards the experimental realization of these machines (which I will review), but there are still many questions about how such a machine could solve computational problems of interest in quantum physics. New categorizations of the complexity of computational problems have now been invented to describe quantum simulation. The bad news is that some of these problems are believed to be intractable even on a quantum computer, falling into a quantum analog of the NP class. The good news is that there are many other new classifications of tractability that may apply to several situations of physical interest.

  9. THE COMPUTER AND THE ARCHITECTURAL PROFESSION.

    ERIC Educational Resources Information Center

    HAVILAND, DAVID S.

    THE ROLE OF ADVANCING TECHNOLOGY IN THE FIELD OF ARCHITECTURE IS DISCUSSED IN THIS REPORT. PROBLEMS IN COMMUNICATION AND THE DESIGN PROCESS ARE IDENTIFIED. ADVANTAGES AND DISADVANTAGES OF COMPUTERS ARE MENTIONED IN RELATION TO MAN AND MACHINE INTERACTION. PRESENT AND FUTURE IMPLICATIONS OF COMPUTER USAGE ARE IDENTIFIED AND DISCUSSED WITH RESPECT…

  10. Switching from Computer to Microcomputer Architecture Education

    ERIC Educational Resources Information Center

    Bolanakis, Dimosthenis E.; Kotsis, Konstantinos T.; Laopoulos, Theodore

    2010-01-01

    In the last decades, the technological and scientific evolution of the computing discipline has been widely affecting research in software engineering education, which nowadays advocates more enlightened and liberal ideas. This article reviews cross-disciplinary research on a computer architecture class in consideration of its switching to…

  11. Efficient universal blind quantum computation.

    PubMed

    Giovannetti, Vittorio; Maccone, Lorenzo; Morimae, Tomoyuki; Rudolph, Terry G

    2013-12-01

    We give a cheat sensitive protocol for blind universal quantum computation that is efficient in terms of computational and communication resources: it allows one party to perform an arbitrary computation on a second party's quantum computer without revealing either which computation is performed, or its input and output. The first party's computational capabilities can be extremely limited: she must only be able to create and measure single-qubit superposition states. The second party is not required to use measurement-based quantum computation. The protocol requires the (optimal) exchange of O(Jlog2(N)) single-qubit states, where J is the computational depth and N is the number of qubits needed for the computation. PMID:24476238

  12. Efficient Universal Blind Quantum Computation

    NASA Astrophysics Data System (ADS)

    Giovannetti, Vittorio; Maccone, Lorenzo; Morimae, Tomoyuki; Rudolph, Terry G.

    2013-12-01

    We give a cheat sensitive protocol for blind universal quantum computation that is efficient in terms of computational and communication resources: it allows one party to perform an arbitrary computation on a second party’s quantum computer without revealing either which computation is performed, or its input and output. The first party’s computational capabilities can be extremely limited: she must only be able to create and measure single-qubit superposition states. The second party is not required to use measurement-based quantum computation. The protocol requires the (optimal) exchange of O(Jlog⁡2(N)) single-qubit states, where J is the computational depth and N is the number of qubits needed for the computation.

  13. Duality quantum computer and the efficient quantum simulations

    NASA Astrophysics Data System (ADS)

    Wei, Shi-Jie; Long, Gui-Lu

    2016-03-01

    Duality quantum computing is a new mode of a quantum computer to simulate a moving quantum computer passing through a multi-slit. It exploits the particle wave duality property for computing. A quantum computer with n qubits and a qudit simulates a moving quantum computer with n qubits passing through a d-slit. Duality quantum computing can realize an arbitrary sum of unitaries and therefore a general quantum operator, which is called a generalized quantum gate. All linear bounded operators can be realized by the generalized quantum gates, and unitary operators are just the extreme points of the set of generalized quantum gates. Duality quantum computing provides flexibility and a clear physical picture in designing quantum algorithms, and serves as a powerful bridge between quantum and classical algorithms. In this paper, after a brief review of the theory of duality quantum computing, we will concentrate on the applications of duality quantum computing in simulations of Hamiltonian systems. We will show that duality quantum computing can efficiently simulate quantum systems by providing descriptions of the recent efficient quantum simulation algorithm of Childs and Wiebe (Quantum Inf Comput 12(11-12):901-924, 2012) for the fast simulation of quantum systems with a sparse Hamiltonian, and the quantum simulation algorithm by Berry et al. (Phys Rev Lett 114:090502, 2015), which provides exponential improvement in precision for simulating systems with a sparse Hamiltonian.

  14. Quantum computing accelerator I/O : LDRD 52750 final report.

    SciTech Connect

    Schroeppel, Richard Crabtree; Modine, Normand Arthur; Ganti, Anand; Pierson, Lyndon George; Tigges, Christopher P.

    2003-12-01

    In a superposition of quantum states, a bit can be in both the states '0' and '1' at the same time. This feature of the quantum bit or qubit has no parallel in classical systems. Currently, quantum computers consisting of 4 to 7 qubits in a 'quantum computing register' have been built. Innovative algorithms suited to quantum computing are now beginning to emerge, applicable to sorting and cryptanalysis, and other applications. A framework for overcoming slightly inaccurate quantum gate interactions and for causing quantum states to survive interactions with surrounding environment is emerging, called quantum error correction. Thus there is the potential for rapid advances in this field. Although quantum information processing can be applied to secure communication links (quantum cryptography) and to crack conventional cryptosystems, the first few computing applications will likely involve a 'quantum computing accelerator' similar to a 'floating point arithmetic accelerator' interfaced to a conventional Von Neumann computer architecture. This research is to develop a roadmap for applying Sandia's capabilities to the solution of some of the problems associated with maintaining quantum information, and with getting data into and out of such a 'quantum computing accelerator'. We propose to focus this work on 'quantum I/O technologies' by applying quantum optics on semiconductor nanostructures to leverage Sandia's expertise in semiconductor microelectronic/photonic fabrication techniques, as well as its expertise in information theory, processing, and algorithms. The work will be guided by understanding of practical requirements of computing and communication architectures. This effort will incorporate ongoing collaboration between 9000, 6000 and 1000 and between junior and senior personnel. Follow-on work to fabricate and evaluate appropriate experimental nano/microstructures will be proposed as a result of this work.

  15. Toward a superconducting quantum computer

    PubMed Central

    Tsai, Jaw-Shen

    2010-01-01

    Intensive research on the construction of superconducting quantum computers has produced numerous important achievements. The quantum bit (qubit), based on the Josephson junction, is at the heart of this research. This macroscopic system has the ability to control quantum coherence. This article reviews the current state of quantum computing as well as its history, and discusses its future. Although progress has been rapid, the field remains beset with unsolved issues, and there are still many new research opportunities open to physicists and engineers. PMID:20431256

  16. Quantum Information and Computing

    NASA Astrophysics Data System (ADS)

    Accardi, L.; Ohya, Masanori; Watanabe, N.

    2006-03-01

    Preface -- Coherent quantum control of [symbol]-atoms through the stochastic limit / L. Accardi, S. V. Kozyrev and A. N. Pechen -- Recent advances in quantum white noise calculus / L. Accardi and A. Boukas -- Control of quantum states by decoherence / L. Accardi and K. Imafuku -- Logical operations realized on the Ising chain of N qubits / M. Asano, N. Tateda and C. Ishii -- Joint extension of states of fermion subsystems / H. Araki -- Quantum filtering and optimal feedback control of a Gaussian quantum free particle / S. C. Edwards and V. P. Belavkin -- On existence of quantum zeno dynamics / P. Exner and T. Ichinose -- Invariant subspaces and control of decoherence / P. Facchi, V. L. Lepore and S. Pascazio -- Clauser-Horner inequality for electron counting statistics in multiterminal mesoscopic conductors / L. Faoro, F. Taddei and R. Fazio -- Fidelity of quantum teleportation model using beam splittings / K.-H. Fichtner, T. Miyadera and M. Ohya -- Quantum logical gates realized by beam splittings / W. Freudenberg ... [et al.] -- Information divergence for quantum channels / S. J. Hammersley and V. P. Belavkin -- On the uniqueness theorem in quantum information geometry / H. Hasegawa -- Noncanonical representations of a multi-dimensional Brownian motion / Y. Hibino -- Some of future directions of white noise theory / T. Hida -- Information, innovation and elemental random field / T. Hida -- Generalized quantum turing machine and its application to the SAT chaos algorithm / S. Iriyama, M. Ohya and I. Volovich -- A Stroboscopic approach to quantum tomography / A. Jamiolkowski -- Positive maps and separable states in matrix algebras / A. Kossakowski -- Simulating open quantum systems with trapped ions / S. Maniscalco -- A purification scheme and entanglement distillations / H. Nakazato, M. Unoki and K. Yuasa -- Generalized sectors and adjunctions to control micro-macro transitions / I. Ojima -- Saturation of an entropy bound and quantum Markov states / D. Petz -- An

  17. The new landscape of parallel computer architecture

    NASA Astrophysics Data System (ADS)

    Shalf, John

    2007-07-01

    The past few years has seen a sea change in computer architecture that will impact every facet of our society as every electronic device from cell phone to supercomputer will need to confront parallelism of unprecedented scale. Whereas the conventional multicore approach (2, 4, and even 8 cores) adopted by the computing industry will eventually hit a performance plateau, the highest performance per watt and per chip area is achieved using manycore technology (hundreds or even thousands of cores). However, fully unleashing the potential of the manycore approach to ensure future advances in sustained computational performance will require fundamental advances in computer architecture and programming models that are nothing short of reinventing computing. In this paper we examine the reasons behind the movement to exponentially increasing parallelism, and its ramifications for system design, applications and programming models.

  18. Quantum computation and hidden variables

    NASA Astrophysics Data System (ADS)

    Aristov, V. V.; Nikulov, A. V.

    2008-03-01

    Many physicists limit oneself to an instrumentalist description of quantum phenomena and ignore the problems of foundation and interpretation of quantum mechanics. This instrumentalist approach results to "specialization barbarism" and mass delusion concerning the problem, how a quantum computer can be made. The idea of quantum computation can be described within the limits of quantum formalism. But in order to understand how this idea can be put into practice one should realize the question: "What could the quantum formalism describe?", in spite of the absence of an universally recognized answer. Only a realization of this question and the undecided problem of quantum foundations allows to see in which quantum systems the superposition and EPR correlation could be expected. Because of the "specialization barbarism" many authors are sure that Bell proved full impossibility of any hidden-variables interpretation. Therefore it is important to emphasize that in reality Bell has restricted to validity limits of the no-hidden-variables proof and has shown that two-state quantum system can be described by hidden variables. The later means that no experimental result obtained on two-state quantum system can prove the existence of superposition and violation of the realism. One should not assume before unambiguous experimental evidence that any two-state quantum system is quantum bit. No experimental evidence of superposition of macroscopically distinct quantum states and of a quantum bit on base of superconductor structure was obtained for the present. Moreover same experimental results can not be described in the limits of the quantum formalism.

  19. Quantum computation using geometric algebra

    NASA Astrophysics Data System (ADS)

    Matzke, Douglas James

    This dissertation reports that arbitrary Boolean logic equations and operators can be represented in geometric algebra as linear equations composed entirely of orthonormal vectors using only addition and multiplication Geometric algebra is a topologically based algebraic system that naturally incorporates the inner and anticommutative outer products into a real valued geometric product, yet does not rely on complex numbers or matrices. A series of custom tools was designed and built to simplify geometric algebra expressions into a standard sum of products form, and automate the anticommutative geometric product and operations. Using this infrastructure, quantum bits (qubits), quantum registers and EPR-bits (ebits) are expressed symmetrically as geometric algebra expressions. Many known quantum computing gates, measurement operators, and especially the Bell/magic operators are also expressed as geometric products. These results demonstrate that geometric algebra can naturally and faithfully represent the central concepts, objects, and operators necessary for quantum computing, and can facilitate the design and construction of quantum computing tools.

  20. Cryptography, quantum computation and trapped ions

    SciTech Connect

    Hughes, Richard J.

    1998-03-01

    The significance of quantum computation for cryptography is discussed. Following a brief survey of the requirements for quantum computational hardware, an overview of the ion trap quantum computation project at Los Alamos is presented. The physical limitations to quantum computation with trapped ions are analyzed and an assessment of the computational potential of the technology is made.

  1. Using computer algebra in quantum computation and quantum games

    NASA Astrophysics Data System (ADS)

    Bolívar, David A.

    2011-05-01

    Research in contemporary physics is emphasizing the development and evolution of computer systems to facilitate the calculations. Quantum computing is a branch of modern physics is believed promising results for the future, Thanks to the ability of qubits to store more information than a bit. The work of this paper focuses on the simulation of certain quantum algorithms such as the prisoner's dilemma in its quantum version using the MATHEMATICA® software and implementing stochastic version of the software MAPLE ® and the Grover search algorithm that simulates finding a needle in a haystack.

  2. The Fermilab Central Computing Facility architectural model

    SciTech Connect

    Nicholls, J.

    1989-05-01

    The goal of the current Central Computing Upgrade at Fermilab is to create a computing environment that maximizes total productivity, particularly for high energy physics analysis. The Computing Department and the Next Computer Acquisition Committee decided upon a model which includes five components: an interactive front end, a Large-Scale Scientific Computer (LSSC, a mainframe computing engine), a microprocessor farm system, a file server, and workstations. With the exception of the file server, all segments of this model are currently in production: a VAX/VMS Cluster interactive front end, an Amdahl VM computing engine, ACP farms, and (primarily) VMS workstations. This presentation will discuss the implementation of the Fermilab Central Computing Facility Architectural Model. Implications for Code Management in such a heterogeneous environment, including issues such as modularity and centrality, will be considered. Special emphasis will be placed on connectivity and communications between the front-end, LSSC, and workstations, as practiced at Fermilab. 2 figs.

  3. Computing on Knights and Kepler Architectures

    NASA Astrophysics Data System (ADS)

    Bortolotti, G.; Caberletti, M.; Crimi, G.; Ferraro, A.; Giacomini, F.; Manzali, M.; Maron, G.; Pivanti, M.; Salomoni, D.; Schifano, S. F.; Tripiccione, R.; Zanella, M.

    2014-06-01

    A recent trend in scientific computing is the increasingly important role of co-processors, originally built to accelerate graphics rendering, and now used for general high-performance computing. The INFN Computing On Knights and Kepler Architectures (COKA) project focuses on assessing the suitability of co-processor boards for scientific computing in a wide range of physics applications, and on studying the best programming methodologies for these systems. Here we present in a comparative way our results in porting a Lattice Boltzmann code on two state-of-the-art accelerators: the NVIDIA K20X, and the Intel Xeon-Phi. We describe our implementations, analyze results and compare with a baseline architecture adopting Intel Sandy Bridge CPUs.

  4. Quantum chromodynamics with advanced computing

    SciTech Connect

    Kronfeld, Andreas S.; /Fermilab

    2008-07-01

    We survey results in lattice quantum chromodynamics from groups in the USQCD Collaboration. The main focus is on physics, but many aspects of the discussion are aimed at an audience of computational physicists.

  5. The quantum computer game: citizen science

    NASA Astrophysics Data System (ADS)

    Damgaard, Sidse; Mølmer, Klaus; Sherson, Jacob

    2013-05-01

    Progress in the field of quantum computation is hampered by daunting technical challenges. Here we present an alternative approach to solving these by enlisting the aid of computer players around the world. We have previously examined a quantum computation architecture involving ultracold atoms in optical lattices and strongly focused tweezers of light. In The Quantum Computer Game (see http://www.scienceathome.org/), we have encapsulated the time-dependent Schrödinger equation for the problem in a graphical user interface allowing for easy user input. Players can then search the parameter space with real-time graphical feedback in a game context with a global high-score that rewards short gate times and robustness to experimental errors. The game which is still in a demo version has so far been tried by several hundred players. Extensions of the approach to other models such as Gross-Pitaevskii and Bose-Hubbard are currently under development. The game has also been incorporated into science education at high-school and university level as an alternative method for teaching quantum mechanics. Initial quantitative evaluation results are very positive. AU Ideas Center for Community Driven Research, CODER.

  6. Evaluation of Visual Computer Simulator for Computer Architecture Education

    ERIC Educational Resources Information Center

    Imai, Yoshiro; Imai, Masatoshi; Moritoh, Yoshio

    2013-01-01

    This paper presents trial evaluation of a visual computer simulator in 2009-2011, which has been developed to play some roles of both instruction facility and learning tool simultaneously. And it illustrates an example of Computer Architecture education for University students and usage of e-Learning tool for Assembly Programming in order to…

  7. Highly parallel computer architecture for robotic computation

    NASA Technical Reports Server (NTRS)

    Fijany, Amir (Inventor); Bejczy, Anta K. (Inventor)

    1991-01-01

    In a computer having a large number of single instruction multiple data (SIMD) processors, each of the SIMD processors has two sets of three individual processor elements controlled by a master control unit and interconnected among a plurality of register file units where data is stored. The register files input and output data in synchronism with a minor cycle clock under control of two slave control units controlling the register file units connected to respective ones of the two sets of processor elements. Depending upon which ones of the register file units are enabled to store or transmit data during a particular minor clock cycle, the processor elements within an SIMD processor are connected in rings or in pipeline arrays, and may exchange data with the internal bus or with neighboring SIMD processors through interface units controlled by respective ones of the two slave control units.

  8. ATCA for Machines-- Advanced Telecommunications Computing Architecture

    SciTech Connect

    Larsen, R.S.; /SLAC

    2008-04-22

    The Advanced Telecommunications Computing Architecture is a new industry open standard for electronics instrument modules and shelves being evaluated for the International Linear Collider (ILC). It is the first industrial standard designed for High Availability (HA). ILC availability simulations have shown clearly that the capabilities of ATCA are needed in order to achieve acceptable integrated luminosity. The ATCA architecture looks attractive for beam instruments and detector applications as well. This paper provides an overview of ongoing R&D including application of HA principles to power electronics systems.

  9. Implementing a computing architecture with WISDOM

    SciTech Connect

    Zebrowski, J.R.

    1991-01-01

    Over the past two years, the Savannah River Site (SRS) work force has expanded by more than 6000 employees. This large influx of personnel, in conjunction with the limited office space, has resulted in an overcrowding problem on site. To alleviate some of the overcrowding, Westinghouse Savannah River Company (WSRC) has been in the process of leasing space from several office buildings within Aiken, SC. Brookhaven, the latest off-site office building to be leased, is the starting point for a new direction in office automation which will eventually spread throughout SRS. The computing architecture in place at Brookhaven was designed to adhere to the SRS computer architecture guidelines as published by the WSRC Computer Architecture Standards Team (CAST). At the heart of the Brookhaven implementation is a Workstation Integration System for DOS, OS/2 and Macintosh (WISDOM). The key features of the WISDOM system include: it's utilization of a Local Area Network (LAN), it's Graphical User Interface (GUI), it's cross-platform capability, it's portable user interface, and the installation program. To begin, I will give an overview of the network architecture, then discuss WISDOM in detail, mention some platform integration problems that need to be addressed and conclude with a summary of the user benefits that WISDOM provides.

  10. Implementing a computing architecture with WISDOM

    SciTech Connect

    Zebrowski, J.R.

    1991-12-31

    Over the past two years, the Savannah River Site (SRS) work force has expanded by more than 6000 employees. This large influx of personnel, in conjunction with the limited office space, has resulted in an overcrowding problem on site. To alleviate some of the overcrowding, Westinghouse Savannah River Company (WSRC) has been in the process of leasing space from several office buildings within Aiken, SC. Brookhaven, the latest off-site office building to be leased, is the starting point for a new direction in office automation which will eventually spread throughout SRS. The computing architecture in place at Brookhaven was designed to adhere to the SRS computer architecture guidelines as published by the WSRC Computer Architecture Standards Team (CAST). At the heart of the Brookhaven implementation is a Workstation Integration System for DOS, OS/2 and Macintosh (WISDOM). The key features of the WISDOM system include: it`s utilization of a Local Area Network (LAN), it`s Graphical User Interface (GUI), it`s cross-platform capability, it`s portable user interface, and the installation program. To begin, I will give an overview of the network architecture, then discuss WISDOM in detail, mention some platform integration problems that need to be addressed and conclude with a summary of the user benefits that WISDOM provides.

  11. Computer graphics in architecture and engineering

    NASA Technical Reports Server (NTRS)

    Greenberg, D. P.

    1975-01-01

    The present status of the application of computer graphics to the building profession or architecture and its relationship to other scientific and technical areas were discussed. It was explained that, due to the fragmented nature of architecture and building activities (in contrast to the aerospace industry), a comprehensive, economic utilization of computer graphics in this area is not practical and its true potential cannot now be realized due to the present inability of architects and structural, mechanical, and site engineers to rely on a common data base. Future emphasis will therefore have to be placed on a vertical integration of the construction process and effective use of a three-dimensional data base, rather than on waiting for any technological breakthrough in interactive computing.

  12. Efficient tree codes on SIMD computer architectures

    NASA Astrophysics Data System (ADS)

    Olson, Kevin M.

    1996-11-01

    This paper describes changes made to a previous implementation of an N -body tree code developed for a fine-grained, SIMD computer architecture. These changes include (1) switching from a balanced binary tree to a balanced oct tree, (2) addition of quadrupole corrections, and (3) having the particles search the tree in groups rather than individually. An algorithm for limiting errors is also discussed. In aggregate, these changes have led to a performance increase of over a factor of 10 compared to the previous code. For problems several times larger than the processor array, the code now achieves performance levels of ~ 1 Gflop on the Maspar MP-2 or roughly 20% of the quoted peak performance of this machine. This percentage is competitive with other parallel implementations of tree codes on MIMD architectures. This is significant, considering the low relative cost of SIMD architectures.

  13. Towards optoelectronic architectures for integrated neuromorphic computers

    NASA Astrophysics Data System (ADS)

    Martinenghi, Romain; Baylon Fuentes, Antonio; Jacquot, Maxime; Chembo, Yanne K.; Larger, Laurent

    2014-03-01

    We investigate theoretically and experimentally the computational properties of an optoelectronic neuromorphic processor based on a complex nonlinear dynamics. This neuromorphic approach is based on a new paradigm of or reservoir computing, which is intrinsically different from the concept of Turing machines. It essentially consists in expanding the input information to be processed into a higher dimensional phase space, through the nonlinear transient response of a complex dynamics excited by the input information. The computed output is then extracted via a linear separation of the transient trajectory in the complex phase space, performed through a learning phase consisting of the resolution of a regression problem. We here investigate an architecture for photonic neuromorphic computing via these complex nonlinear dynamical transients. A versatile photonic nonlinear transient computer based on a multiple-delay is reported. Its hybrid analogue and digital architecture allows for an easy reconfiguration, and for direct implementation of in-line processing. Its computational efficiency in parameter space is also analyzed, and the computational performance of this system is successfully evaluated on a standard spoken digit recognition task. We then discuss the pathways that can lead to its effective integration.

  14. Pfaffian States: Quantum Computation

    SciTech Connect

    Shrivastava, Keshav N.

    2009-09-14

    The Pfaffian determinant is sometimes used to multiply the Laughlin's wave function at the half filled Landau level. The square of the Pfaffian gives the ordinary determinant. We find that the Pfaffian wave function leads to four times larger energies and two times faster time. By the same logic, the Pfaffian breaks the supersymmetry of the Dirac equation. By using the spin properties and the Landau levels, we correctly interpret the state with 5/2 filling. The quantum numbers which represent the state vectors are now products of n (Landau level quantum number), l(orbital angular momentum quantum number and the spin, s |n, l, s>. In a circuit, the noise measures the resistivity and hence the charge. The Pfaffian velocity is different from that of the single-particle states and hence it has important consequences in the measurement of the charge of the quasiparticles.

  15. Roadmap to the SRS computing architecture

    SciTech Connect

    Johnson, A.

    1994-07-05

    This document outlines the major steps that must be taken by the Savannah River Site (SRS) to migrate the SRS information technology (IT) environment to the new architecture described in the Savannah River Site Computing Architecture. This document proposes an IT environment that is {open_quotes}...standards-based, data-driven, and workstation-oriented, with larger systems being utilized for the delivery of needed information to users in a client-server relationship.{close_quotes} Achieving this vision will require many substantial changes in the computing applications, systems, and supporting infrastructure at the site. This document consists of a set of roadmaps which provide explanations of the necessary changes for IT at the site and describes the milestones that must be completed to finish the migration.

  16. Scalable computer architecture for digital vascular systems

    NASA Astrophysics Data System (ADS)

    Goddard, Iain; Chao, Hui; Skalabrin, Mark

    1998-06-01

    Digital vascular computer systems are used for radiology and fluoroscopy (R/F), angiography, and cardiac applications. In the United States alone, about 26 million procedures of these types are performed annually: about 81% R/F, 11% cardiac, and 8% angiography. Digital vascular systems have a very wide range of performance requirements, especially in terms of data rates. In addition, new features are added over time as they are shown to be clinically efficacious. Application-specific processing modes such as roadmapping, peak opacification, and bolus chasing are particular to some vascular systems. New algorithms continue to be developed and proven, such as Cox and deJager's precise registration methods for masks and live images in digital subtraction angiography. A computer architecture must have high scalability and reconfigurability to meet the needs of this modality. Ideally, the architecture could also serve as the basis for a nonvascular R/F system.

  17. Quantumness, Randomness and Computability

    NASA Astrophysics Data System (ADS)

    Solis, Aldo; Hirsch, Jorge G.

    2015-06-01

    Randomness plays a central role in the quantum mechanical description of our interactions. We review the relationship between the violation of Bell inequalities, non signaling and randomness. We discuss the challenge in defining a random string, and show that algorithmic information theory provides a necessary condition for randomness using Borel normality. We close with a view on incomputablity and its implications in physics.

  18. Nonlinear hierarchical substructural parallelism and computer architecture

    NASA Technical Reports Server (NTRS)

    Padovan, Joe

    1989-01-01

    Computer architecture is investigated in conjunction with the algorithmic structures of nonlinear finite-element analysis. To help set the stage for this goal, the development is undertaken by considering the wide-ranging needs associated with the analysis of rolling tires which possess the full range of kinematic, material and boundary condition induced nonlinearity in addition to gross and local cord-matrix material properties.

  19. Maximum density of quantum information in a scalable CMOS implementation of the hybrid qubit architecture

    NASA Astrophysics Data System (ADS)

    Rotta, Davide; De Michielis, Marco; Ferraro, Elena; Fanciulli, Marco; Prati, Enrico

    2016-06-01

    Scalability from single-qubit operations to multi-qubit circuits for quantum information processing requires architecture-specific implementations. Semiconductor hybrid qubit architecture is a suitable candidate to realize large-scale quantum information processing, as it combines a universal set of logic gates with fast and all-electrical manipulation of qubits. We propose an implementation of hybrid qubits, based on Si metal-oxide-semiconductor (MOS) quantum dots, compatible with the CMOS industrial technological standards. We discuss the realization of multi-qubit circuits capable of fault-tolerant computation and quantum error correction, by evaluating the time and space resources needed for their implementation. As a result, the maximum density of quantum information is extracted from a circuit including eight logical qubits encoded by the [[7, 1, 3

  20. Maximum density of quantum information in a scalable CMOS implementation of the hybrid qubit architecture

    NASA Astrophysics Data System (ADS)

    Rotta, Davide; De Michielis, Marco; Ferraro, Elena; Fanciulli, Marco; Prati, Enrico

    2016-03-01

    Scalability from single-qubit operations to multi-qubit circuits for quantum information processing requires architecture-specific implementations. Semiconductor hybrid qubit architecture is a suitable candidate to realize large-scale quantum information processing, as it combines a universal set of logic gates with fast and all-electrical manipulation of qubits. We propose an implementation of hybrid qubits, based on Si metal-oxide-semiconductor (MOS) quantum dots, compatible with the CMOS industrial technological standards. We discuss the realization of multi-qubit circuits capable of fault-tolerant computation and quantum error correction, by evaluating the time and space resources needed for their implementation. As a result, the maximum density of quantum information is extracted from a circuit including eight logical qubits encoded by the [[7, 1, 3

  1. Fast semivariogram computation using FPGA architectures

    NASA Astrophysics Data System (ADS)

    Lagadapati, Yamuna; Shirvaikar, Mukul; Dong, Xuanliang

    2015-02-01

    The semivariogram is a statistical measure of the spatial distribution of data and is based on Markov Random Fields (MRFs). Semivariogram analysis is a computationally intensive algorithm that has typically seen applications in the geosciences and remote sensing areas. Recently, applications in the area of medical imaging have been investigated, resulting in the need for efficient real time implementation of the algorithm. The semivariogram is a plot of semivariances for different lag distances between pixels. A semi-variance, γ(h), is defined as the half of the expected squared differences of pixel values between any two data locations with a lag distance of h. Due to the need to examine each pair of pixels in the image or sub-image being processed, the base algorithm complexity for an image window with n pixels is O(n2). Field Programmable Gate Arrays (FPGAs) are an attractive solution for such demanding applications due to their parallel processing capability. FPGAs also tend to operate at relatively modest clock rates measured in a few hundreds of megahertz, but they can perform tens of thousands of calculations per clock cycle while operating in the low range of power. This paper presents a technique for the fast computation of the semivariogram using two custom FPGA architectures. The design consists of several modules dedicated to the constituent computational tasks. A modular architecture approach is chosen to allow for replication of processing units. This allows for high throughput due to concurrent processing of pixel pairs. The current implementation is focused on isotropic semivariogram computations only. Anisotropic semivariogram implementation is anticipated to be an extension of the current architecture, ostensibly based on refinements to the current modules. The algorithm is benchmarked using VHDL on a Xilinx XUPV5-LX110T development Kit, which utilizes the Virtex5 FPGA. Medical image data from MRI scans are utilized for the experiments

  2. Atomic physics: A milestone in quantum computing

    NASA Astrophysics Data System (ADS)

    Bartlett, Stephen D.

    2016-08-01

    Quantum computers require many quantum bits to perform complex calculations, but devices with more than a few bits are difficult to program. A device based on five atomic quantum bits shows a way forward. See Letter p.63

  3. Continuous-Variable Blind Quantum Computation

    NASA Astrophysics Data System (ADS)

    Morimae, Tomoyuki

    2012-12-01

    Blind quantum computation is a secure delegated quantum computing protocol where Alice, who does not have sufficient quantum technology at her disposal, delegates her computation to Bob, who has a fully fledged quantum computer, in such a way that Bob cannot learn anything about Alice’s input, output, and algorithm. Protocols of blind quantum computation have been proposed for several qudit measurement-based computation models, such as the graph state model, the Affleck-Kennedy-Lieb-Tasaki model, and the Raussendorf-Harrington-Goyal topological model. Here, we consider blind quantum computation for the continuous-variable measurement-based model. We show that blind quantum computation is possible for the infinite squeezing case. We also show that the finite squeezing causes no additional problem in the blind setup apart from the one inherent to the continuous-variable measurement-based quantum computation.

  4. Quantum Computing and Number Theory

    NASA Astrophysics Data System (ADS)

    Sasaki, Yoshitaka

    2013-09-01

    The prime factorization can be efficiently solved on a quantum computer. This result was given by Shor in 1994. In the first half of this article, a review of Shor's algorithm with mathematical setups is given. In the second half of this article, the prime number theorem which is an essential tool to understand the distribution of prime numbers is given.

  5. ASCR Workshop on Quantum Computing for Science

    SciTech Connect

    Aspuru-Guzik, Alan; Van Dam, Wim; Farhi, Edward; Gaitan, Frank; Humble, Travis; Jordan, Stephen; Landahl, Andrew J; Love, Peter; Lucas, Robert; Preskill, John; Muller, Richard P.; Svore, Krysta; Wiebe, Nathan; Williams, Carl

    2015-06-01

    This report details the findings of the DOE ASCR Workshop on Quantum Computing for Science that was organized to assess the viability of quantum computing technologies to meet the computational requirements of the DOE’s science and energy mission, and to identify the potential impact of quantum technologies. The workshop was held on February 17-18, 2015, in Bethesda, MD, to solicit input from members of the quantum computing community. The workshop considered models of quantum computation and programming environments, physical science applications relevant to DOE's science mission as well as quantum simulation, and applied mathematics topics including potential quantum algorithms for linear algebra, graph theory, and machine learning. This report summarizes these perspectives into an outlook on the opportunities for quantum computing to impact problems relevant to the DOE’s mission as well as the additional research required to bring quantum computing to the point where it can have such impact.

  6. Developing a Distributed Computing Architecture at Arizona State University.

    ERIC Educational Resources Information Center

    Armann, Neil; And Others

    1994-01-01

    Development of Arizona State University's computing architecture, designed to ensure that all new distributed computing pieces will work together, is described. Aspects discussed include the business rationale, the general architectural approach, characteristics and objectives of the architecture, specific services, and impact on the university…

  7. Hybrid VLSI/QCA Architecture for Computing FFTs

    NASA Technical Reports Server (NTRS)

    Fijany, Amir; Toomarian, Nikzad; Modarres, Katayoon; Spotnitz, Matthew

    2003-01-01

    A data-processor architecture that would incorporate elements of both conventional very-large-scale integrated (VLSI) circuitry and quantum-dot cellular automata (QCA) has been proposed to enable the highly parallel and systolic computation of fast Fourier transforms (FFTs). The proposed circuit would complement the QCA-based circuits described in several prior NASA Tech Briefs articles, namely Implementing Permutation Matrices by Use of Quantum Dots (NPO-20801), Vol. 25, No. 10 (October 2001), page 42; Compact Interconnection Networks Based on Quantum Dots (NPO-20855) Vol. 27, No. 1 (January 2003), page 32; and Bit-Serial Adder Based on Quantum Dots (NPO-20869), Vol. 27, No. 1 (January 2003), page 35. The cited prior articles described the limitations of very-large-scale integrated (VLSI) circuitry and the major potential advantage afforded by QCA. To recapitulate: In a VLSI circuit, signal paths that are required not to interact with each other must not cross in the same plane. In contrast, for reasons too complex to describe in the limited space available for this article, suitably designed and operated QCAbased signal paths that are required not to interact with each other can nevertheless be allowed to cross each other in the same plane without adverse effect. In principle, this characteristic could be exploited to design compact, coplanar, simple (relative to VLSI) QCA-based networks to implement complex, advanced interconnection schemes.

  8. Frances: A Tool for Understanding Computer Architecture and Assembly Language

    ERIC Educational Resources Information Center

    Sondag, Tyler; Pokorny, Kian L.; Rajan, Hridesh

    2012-01-01

    Students in all areas of computing require knowledge of the computing device including software implementation at the machine level. Several courses in computer science curricula address these low-level details such as computer architecture and assembly languages. For such courses, there are advantages to studying real architectures instead of…

  9. General Quantum Interference Principle and Duality Computer

    NASA Astrophysics Data System (ADS)

    Long, Gui-Lu

    2006-05-01

    In this article, we propose a general principle of quantum interference for quantum system, and based on this we propose a new type of computing machine, the duality computer, that may outperform in principle both classical computer and the quantum computer. According to the general principle of quantum interference, the very essence of quantum interference is the interference of the sub-waves of the quantum system itself. A quantum system considered here can be any quantum system: a single microscopic particle, a composite quantum system such as an atom or a molecule, or a loose collection of a few quantum objects such as two independent photons. In the duality computer, the wave of the duality computer is split into several sub-waves and they pass through different routes, where different computing gate operations are performed. These sub-waves are then re-combined to interfere to give the computational results. The quantum computer, however, has only used the particle nature of quantum object. In a duality computer, it may be possible to find a marked item from an unsorted database using only a single query, and all NP-complete problems may have polynomial algorithms. Two proof-of-the-principle designs of the duality computer are presented: the giant molecule scheme and the nonlinear quantum optics scheme. We also propose thought experiment to check the related fundamental issues, the measurement efficiency of a partial wave function.

  10. Computer architecture evaluation for structural dynamics computations: Project summary

    NASA Technical Reports Server (NTRS)

    Standley, Hilda M.

    1989-01-01

    The intent of the proposed effort is the examination of the impact of the elements of parallel architectures on the performance realized in a parallel computation. To this end, three major projects are developed: a language for the expression of high level parallelism, a statistical technique for the synthesis of multicomputer interconnection networks based upon performance prediction, and a queueing model for the analysis of shared memory hierarchies.

  11. Hierarchical Poly Tree computer architectures defined by computational multidisciplinary mechanics

    NASA Technical Reports Server (NTRS)

    Padovan, Joe; Gute, Doug; Johnson, Keith

    1989-01-01

    This paper will develop an alternative computer architecture called the Poly Tree. Based on the requirements of computational mechanics and the concept of hierarchical substructuring, the paper will explore the development of problem-dependent parallel networks of processors which will enable significant, often superlinear, speed enhancements; provide a logical/efficient framework for linear/nonlinear and transient structural mechanics problems; and provide a logical framework from which to apply model reduction procedures. In addition, the paper will explore optimal processor arrangements which define the overall system granularity. Consideration will also be given to system I/O requirements.

  12. Quantum computing with parafermions

    NASA Astrophysics Data System (ADS)

    Hutter, Adrian; Loss, Daniel

    2016-03-01

    Zd parafermions are exotic non-Abelian quasiparticles generalizing Majorana fermions, which correspond to the case d =2 . In contrast to Majorana fermions, braiding of parafermions with d >2 allows one to perform an entangling gate. This has spurred interest in parafermions, and a variety of condensed matter systems have been proposed as potential hosts for them. In this work, we study the computational power of braiding parafermions more systematically. We make no assumptions on the underlying physical model but derive all our results from the algebraical relations that define parafermions. We find a family of 2 d representations of the braid group that are compatible with these relations. The braiding operators derived this way reproduce those derived previously from physical grounds as special cases. We show that if a d -level qudit is encoded in the fusion space of four parafermions, braiding of these four parafermions allows one to generate the entire single-qudit Clifford group (up to phases), for any d . If d is odd, then we show that in fact the entire many-qudit Clifford group can be generated.

  13. Brain Neurons as Quantum Computers:

    NASA Astrophysics Data System (ADS)

    Bershadskii, A.; Dremencov, E.; Bershadskii, J.; Yadid, G.

    The question: whether quantum coherent states can sustain decoherence, heating and dissipation over time scales comparable to the dynamical timescales of brain neurons, has been actively discussed in the last years. A positive answer on this question is crucial, in particular, for consideration of brain neurons as quantum computers. This discussion was mainly based on theoretical arguments. In the present paper nonlinear statistical properties of the Ventral Tegmental Area (VTA) of genetically depressive limbic brain are studied in vivo on the Flinders Sensitive Line of rats (FSL). VTA plays a key role in the generation of pleasure and in the development of psychological drug addiction. We found that the FSL VTA (dopaminergic) neuron signals exhibit multifractal properties for interspike frequencies on the scales where healthy VTA dopaminergic neurons exhibit bursting activity. For high moments the observed multifractal (generalized dimensions) spectrum coincides with the generalized dimensions spectrum calculated for a spectral measure of a quantum system (so-called kicked Harper model, actively used as a model of quantum chaos). This observation can be considered as a first experimental (in vivo) indication in the favor of the quantum (at least partially) nature of brain neurons activity.

  14. Quantum dissonance and deterministic quantum computation with a single qubit

    NASA Astrophysics Data System (ADS)

    Ali, Mazhar

    2014-11-01

    Mixed state quantum computation can perform certain tasks which are believed to be efficiently intractable on a classical computer. For a specific model of mixed state quantum computation, namely, deterministic quantum computation with a single qubit (DQC1), recent investigations suggest that quantum correlations other than entanglement might be responsible for the power of DQC1 model. However, strictly speaking, the role of entanglement in this model of computation was not entirely clear. We provide conclusive evidence that there are instances where quantum entanglement is not present in any part of this model, nevertheless we have advantage over classical computation. This establishes the fact that quantum dissonance (a kind of quantum correlations) present in fully separable (FS) states provide power to DQC1 model.

  15. Scalable digital hardware for a trapped ion quantum computer

    NASA Astrophysics Data System (ADS)

    Mount, Emily; Gaultney, Daniel; Vrijsen, Geert; Adams, Michael; Baek, So-Young; Hudek, Kai; Isabella, Louis; Crain, Stephen; van Rynbach, Andre; Maunz, Peter; Kim, Jungsang

    2015-09-01

    Many of the challenges of scaling quantum computer hardware lie at the interface between the qubits and the classical control signals used to manipulate them. Modular ion trap quantum computer architectures address scalability by constructing individual quantum processors interconnected via a network of quantum communication channels. Successful operation of such quantum hardware requires a fully programmable classical control system capable of frequency stabilizing the continuous wave lasers necessary for loading, cooling, initialization, and detection of the ion qubits, stabilizing the optical frequency combs used to drive logic gate operations on the ion qubits, providing a large number of analog voltage sources to drive the trap electrodes, and a scheme for maintaining phase coherence among all the controllers that manipulate the qubits. In this work, we describe scalable solutions to these hardware development challenges.

  16. Geometry of discrete quantum computing

    NASA Astrophysics Data System (ADS)

    Hanson, Andrew J.; Ortiz, Gerardo; Sabry, Amr; Tai, Yu-Tsung

    2013-05-01

    Conventional quantum computing entails a geometry based on the description of an n-qubit state using 2n infinite precision complex numbers denoting a vector in a Hilbert space. Such numbers are in general uncomputable using any real-world resources, and, if we have the idea of physical law as some kind of computational algorithm of the universe, we would be compelled to alter our descriptions of physics to be consistent with computable numbers. Our purpose here is to examine the geometric implications of using finite fields Fp and finite complexified fields \\mathbf {F}_{p^2} (based on primes p congruent to 3 (mod4)) as the basis for computations in a theory of discrete quantum computing, which would therefore become a computable theory. Because the states of a discrete n-qubit system are in principle enumerable, we are able to determine the proportions of entangled and unentangled states. In particular, we extend the Hopf fibration that defines the irreducible state space of conventional continuous n-qubit theories (which is the complex projective space \\mathbf {CP}^{2^{n}-1}) to an analogous discrete geometry in which the Hopf circle for any n is found to be a discrete set of p + 1 points. The tally of unit-length n-qubit states is given, and reduced via the generalized Hopf fibration to \\mathbf {DCP}^{2^{n}-1}, the discrete analogue of the complex projective space, which has p^{2^{n}-1} (p-1)\\,\\prod _{k=1}^{n-1} ( p^{2^{k}}+1) irreducible states. Using a measure of entanglement, the purity, we explore the entanglement features of discrete quantum states and find that the n-qubit states based on the complexified field \\mathbf {F}_{p^2} have pn(p - 1)n unentangled states (the product of the tally for a single qubit) with purity 1, and they have pn + 1(p - 1)(p + 1)n - 1 maximally entangled states with purity zero.

  17. A High Performance COTS Based Computer Architecture

    NASA Astrophysics Data System (ADS)

    Patte, Mathieu; Grimoldi, Raoul; Trautner, Roland

    2014-08-01

    Using Commercial Off The Shelf (COTS) electronic components for space applications is a long standing idea. Indeed the difference in processing performance and energy efficiency between radiation hardened components and COTS components is so important that COTS components are very attractive for use in mass and power constrained systems. However using COTS components in space is not straightforward as one must account with the effects of the space environment on the COTS components behavior. In the frame of the ESA funded activity called High Performance COTS Based Computer, Airbus Defense and Space and its subcontractor OHB CGS have developed and prototyped a versatile COTS based architecture for high performance processing. The rest of the paper is organized as follows: in a first section we will start by recapitulating the interests and constraints of using COTS components for space applications; then we will briefly describe existing fault mitigation architectures and present our solution for fault mitigation based on a component called the SmartIO; in the last part of the paper we will describe the prototyping activities executed during the HiP CBC project.

  18. Computational multiqubit tunnelling in programmable quantum annealers.

    PubMed

    Boixo, Sergio; Smelyanskiy, Vadim N; Shabani, Alireza; Isakov, Sergei V; Dykman, Mark; Denchev, Vasil S; Amin, Mohammad H; Smirnov, Anatoly Yu; Mohseni, Masoud; Neven, Hartmut

    2016-01-01

    Quantum tunnelling is a phenomenon in which a quantum state traverses energy barriers higher than the energy of the state itself. Quantum tunnelling has been hypothesized as an advantageous physical resource for optimization in quantum annealing. However, computational multiqubit tunnelling has not yet been observed, and a theory of co-tunnelling under high- and low-frequency noises is lacking. Here we show that 8-qubit tunnelling plays a computational role in a currently available programmable quantum annealer. We devise a probe for tunnelling, a computational primitive where classical paths are trapped in a false minimum. In support of the design of quantum annealers we develop a nonperturbative theory of open quantum dynamics under realistic noise characteristics. This theory accurately predicts the rate of many-body dissipative quantum tunnelling subject to the polaron effect. Furthermore, we experimentally demonstrate that quantum tunnelling outperforms thermal hopping along classical paths for problems with up to 200 qubits containing the computational primitive. PMID:26739797

  19. Computational multiqubit tunnelling in programmable quantum annealers

    PubMed Central

    Boixo, Sergio; Smelyanskiy, Vadim N.; Shabani, Alireza; Isakov, Sergei V.; Dykman, Mark; Denchev, Vasil S.; Amin, Mohammad H.; Smirnov, Anatoly Yu; Mohseni, Masoud; Neven, Hartmut

    2016-01-01

    Quantum tunnelling is a phenomenon in which a quantum state traverses energy barriers higher than the energy of the state itself. Quantum tunnelling has been hypothesized as an advantageous physical resource for optimization in quantum annealing. However, computational multiqubit tunnelling has not yet been observed, and a theory of co-tunnelling under high- and low-frequency noises is lacking. Here we show that 8-qubit tunnelling plays a computational role in a currently available programmable quantum annealer. We devise a probe for tunnelling, a computational primitive where classical paths are trapped in a false minimum. In support of the design of quantum annealers we develop a nonperturbative theory of open quantum dynamics under realistic noise characteristics. This theory accurately predicts the rate of many-body dissipative quantum tunnelling subject to the polaron effect. Furthermore, we experimentally demonstrate that quantum tunnelling outperforms thermal hopping along classical paths for problems with up to 200 qubits containing the computational primitive. PMID:26739797

  20. Nanophotonic quantum computer based on atomic quantum transistor

    NASA Astrophysics Data System (ADS)

    Andrianov, S. N.; Moiseev, S. A.

    2015-10-01

    We propose a scheme of a quantum computer based on nanophotonic elements: two buses in the form of nanowaveguide resonators, two nanosized units of multiatom multiqubit quantum memory and a set of nanoprocessors in the form of photonic quantum transistors, each containing a pair of nanowaveguide ring resonators coupled via a quantum dot. The operation modes of nanoprocessor photonic quantum transistors are theoretically studied and the execution of main logical operations by means of them is demonstrated. We also discuss the prospects of the proposed nanophotonic quantum computer for operating in high-speed optical fibre networks.

  1. Universal quantum computation using the discrete-time quantum walk

    SciTech Connect

    Lovett, Neil B.; Cooper, Sally; Everitt, Matthew; Trevers, Matthew; Kendon, Viv

    2010-04-15

    A proof that continuous-time quantum walks are universal for quantum computation, using unweighted graphs of low degree, has recently been presented by A. M. Childs [Phys. Rev. Lett. 102, 180501 (2009)]. We present a version based instead on the discrete-time quantum walk. We show that the discrete-time quantum walk is able to implement the same universal gate set and thus both discrete and continuous-time quantum walks are computational primitives. Additionally, we give a set of components on which the discrete-time quantum walk provides perfect state transfer.

  2. The Quantum Human Computer (QHC) Hypothesis

    ERIC Educational Resources Information Center

    Salmani-Nodoushan, Mohammad Ali

    2008-01-01

    This article attempts to suggest the existence of a human computer called Quantum Human Computer (QHC) on the basis of an analogy between human beings and computers. To date, there are two types of computers: Binary and Quantum. The former operates on the basis of binary logic where an object is said to exist in either of the two states of 1 and…

  3. Advanced computer architecture specification for automated weld systems

    NASA Technical Reports Server (NTRS)

    Katsinis, Constantine

    1994-01-01

    This report describes the requirements for an advanced automated weld system and the associated computer architecture, and defines the overall system specification from a broad perspective. According to the requirements of welding procedures as they relate to an integrated multiaxis motion control and sensor architecture, the computer system requirements are developed based on a proven multiple-processor architecture with an expandable, distributed-memory, single global bus architecture, containing individual processors which are assigned to specific tasks that support sensor or control processes. The specified architecture is sufficiently flexible to integrate previously developed equipment, be upgradable and allow on-site modifications.

  4. Fast two-qubit gates for quantum computing in semiconductor quantum dots using a photonic microcavity

    NASA Astrophysics Data System (ADS)

    Solenov, Dmitry; Economou, Sophia E.; Reinecke, T. L.

    2013-01-01

    Implementations for quantum computing require fast single- and multiqubit quantum gate operations. In the case of optically controlled quantum dot qubits, theoretical designs for long-range two- or multiqubit operations satisfying all the requirements in quantum computing are not yet available. We have developed a design for a fast, long-range two-qubit gate mediated by a photonic microcavity mode using excited states of the quantum-dot-cavity system that addresses these needs. This design does not require identical qubits, it is compatible with available optically induced single-qubit operations, and it advances opportunities for scalable architectures. We show that the gate fidelity can exceed 90% in experimentally accessible systems.

  5. Exploring quantum computing application to satellite data assimilation

    NASA Astrophysics Data System (ADS)

    Cheung, S.; Zhang, S. Q.

    2015-12-01

    This is an exploring work on potential application of quantum computing to a scientific data optimization problem. On classical computational platforms, the physical domain of a satellite data assimilation problem is represented by a discrete variable transform, and classical minimization algorithms are employed to find optimal solution of the analysis cost function. The computation becomes intensive and time-consuming when the problem involves large number of variables and data. The new quantum computer opens a very different approach both in conceptual programming and in hardware architecture for solving optimization problem. In order to explore if we can utilize the quantum computing machine architecture, we formulate a satellite data assimilation experimental case in the form of quadratic programming optimization problem. We find a transformation of the problem to map it into Quadratic Unconstrained Binary Optimization (QUBO) framework. Binary Wavelet Transform (BWT) will be applied to the data assimilation variables for its invertible decomposition and all calculations in BWT are performed by Boolean operations. The transformed problem will be experimented as to solve for a solution of QUBO instances defined on Chimera graphs of the quantum computer.

  6. Non-unitary probabilistic quantum computing

    NASA Technical Reports Server (NTRS)

    Gingrich, Robert M.; Williams, Colin P.

    2004-01-01

    We present a method for designing quantum circuits that perform non-unitary quantum computations on n-qubit states probabilistically, and give analytic expressions for the success probability and fidelity.

  7. Zeno effect for quantum computation and control.

    PubMed

    Paz-Silva, Gerardo A; Rezakhani, A T; Dominy, Jason M; Lidar, D A

    2012-02-24

    It is well known that the quantum Zeno effect can protect specific quantum states from decoherence by using projective measurements. Here we combine the theory of weak measurements with stabilizer quantum error correction and detection codes. We derive rigorous performance bounds which demonstrate that the Zeno effect can be used to protect appropriately encoded arbitrary states to arbitrary accuracy while at the same time allowing for universal quantum computation or quantum control. PMID:22463507

  8. Architecture and applications of the HEP multiprocessor computer system

    SciTech Connect

    Smith, B.J.

    1981-01-01

    The HEP computer system is a large scale scientific parallel computer employing shared-resource MIMD architecture. The hardware and software facilities provided by the system are described, and techniques found useful in programming the system are discussed. 3 references.

  9. Blind topological measurement-based quantum computation

    NASA Astrophysics Data System (ADS)

    Morimae, Tomoyuki; Fujii, Keisuke

    2012-09-01

    Blind quantum computation is a novel secure quantum-computing protocol that enables Alice, who does not have sufficient quantum technology at her disposal, to delegate her quantum computation to Bob, who has a fully fledged quantum computer, in such a way that Bob cannot learn anything about Alice's input, output and algorithm. A recent proof-of-principle experiment demonstrating blind quantum computation in an optical system has raised new challenges regarding the scalability of blind quantum computation in realistic noisy conditions. Here we show that fault-tolerant blind quantum computation is possible in a topologically protected manner using the Raussendorf-Harrington-Goyal scheme. The error threshold of our scheme is 4.3×10-3, which is comparable to that (7.5×10-3) of non-blind topological quantum computation. As the error per gate of the order 10-3 was already achieved in some experimental systems, our result implies that secure cloud quantum computation is within reach.

  10. Contextuality supplies the `magic' for quantum computation

    NASA Astrophysics Data System (ADS)

    Howard, Mark; Wallman, Joel; Veitch, Victor; Emerson, Joseph

    2014-06-01

    Quantum computers promise dramatic advantages over their classical counterparts, but the source of the power in quantum computing has remained elusive. Here we prove a remarkable equivalence between the onset of contextuality and the possibility of universal quantum computation via `magic state' distillation, which is the leading model for experimentally realizing a fault-tolerant quantum computer. This is a conceptually satisfying link, because contextuality, which precludes a simple `hidden variable' model of quantum mechanics, provides one of the fundamental characterizations of uniquely quantum phenomena. Furthermore, this connection suggests a unifying paradigm for the resources of quantum information: the non-locality of quantum theory is a particular kind of contextuality, and non-locality is already known to be a critical resource for achieving advantages with quantum communication. In addition to clarifying these fundamental issues, this work advances the resource framework for quantum computation, which has a number of practical applications, such as characterizing the efficiency and trade-offs between distinct theoretical and experimental schemes for achieving robust quantum computation, and putting bounds on the overhead cost for the classical simulation of quantum algorithms.

  11. Contextuality supplies the 'magic' for quantum computation.

    PubMed

    Howard, Mark; Wallman, Joel; Veitch, Victor; Emerson, Joseph

    2014-06-19

    Quantum computers promise dramatic advantages over their classical counterparts, but the source of the power in quantum computing has remained elusive. Here we prove a remarkable equivalence between the onset of contextuality and the possibility of universal quantum computation via 'magic state' distillation, which is the leading model for experimentally realizing a fault-tolerant quantum computer. This is a conceptually satisfying link, because contextuality, which precludes a simple 'hidden variable' model of quantum mechanics, provides one of the fundamental characterizations of uniquely quantum phenomena. Furthermore, this connection suggests a unifying paradigm for the resources of quantum information: the non-locality of quantum theory is a particular kind of contextuality, and non-locality is already known to be a critical resource for achieving advantages with quantum communication. In addition to clarifying these fundamental issues, this work advances the resource framework for quantum computation, which has a number of practical applications, such as characterizing the efficiency and trade-offs between distinct theoretical and experimental schemes for achieving robust quantum computation, and putting bounds on the overhead cost for the classical simulation of quantum algorithms. PMID:24919152

  12. Quantum Computation: Theory, Practice, and Future Prospects

    NASA Astrophysics Data System (ADS)

    Chuang, Isaac

    2000-03-01

    Information is physical, and computation obeys physical laws. Ones and zeros -- elementary classical bits of information -- must be represented in physical media to be stored and processed. Traditionally, these objects are well described by classical physics, but increasingly, as we edge towards the limits of semiconductor technology, we reach a new regime where the laws of quantum physics become dominant. Strange new phenomena, like entanglement and quantum coherence, become available as new resources. How can such resources be utilized for computation? What physical systems allow construction and control of quantum phenomena? How is this relevant to future directions in information technology? The theoretical promise of quantum computation is polynomial speedup of searches, and exponentially speedups for other certain problems such as factoring. But the experimental challenge to realize such algorithms in practice is enormous: to date, quantum computers with only a handful of quantum bits have been realized in the laboratory, using electromagnetically trapped ions, and with magnetic resonance techniques. On the other hand, quantum information has been communicated over long distances using single photons. The future of quantum computation is currently subject to intense scrutiny. It may well be that these machines will not be practical. More quantum algorithms must be discovered, and new physical implementations must be realized. Quantum computation and quantum information are young fields with major issues to be overcome, but already, they have forever changed the way we think of the physical world and what can be computed with it.

  13. The Photon Shell Game and the Quantum von Neumann Architecture with Superconducting Circuits

    NASA Astrophysics Data System (ADS)

    Mariantoni, Matteo

    2012-02-01

    Superconducting quantum circuits have made significant advances over the past decade, allowing more complex and integrated circuits that perform with good fidelity. We have recently implemented a machine comprising seven quantum channels, with three superconducting resonators, two phase qubits, and two zeroing registers. I will explain the design and operation of this machine, first showing how a single microwave photon | 1 > can be prepared in one resonator and coherently transferred between the three resonators. I will also show how more exotic states such as double photon states | 2 > and superposition states | 0 >+ | 1 > can be shuffled among the resonators as well [1]. I will then demonstrate how this machine can be used as the quantum-mechanical analog of the von Neumann computer architecture, which for a classical computer comprises a central processing unit and a memory holding both instructions and data. The quantum version comprises a quantum central processing unit (quCPU) that exchanges data with a quantum random-access memory (quRAM) integrated on one chip, with instructions stored on a classical computer. I will also present a proof-of-concept demonstration of a code that involves all seven quantum elements: (1), Preparing an entangled state in the quCPU, (2), writing it to the quRAM, (3), preparing a second state in the quCPU, (4), zeroing it, and, (5), reading out the first state stored in the quRAM [2]. Finally, I will demonstrate that the quantum von Neumann machine provides one unit cell of a two-dimensional qubit-resonator array that can be used for surface code quantum computing. This will allow the realization of a scalable, fault-tolerant quantum processor with the most forgiving error rates to date. [4pt] [1] M. Mariantoni et al., Nature Physics 7, 287-293 (2011.)[0pt] [2] M. Mariantoni et al., Science 334, 61-65 (2011).

  14. Quantum computing. Defining and detecting quantum speedup.

    PubMed

    Rønnow, Troels F; Wang, Zhihui; Job, Joshua; Boixo, Sergio; Isakov, Sergei V; Wecker, David; Martinis, John M; Lidar, Daniel A; Troyer, Matthias

    2014-07-25

    The development of small-scale quantum devices raises the question of how to fairly assess and detect quantum speedup. Here, we show how to define and measure quantum speedup and how to avoid pitfalls that might mask or fake such a speedup. We illustrate our discussion with data from tests run on a D-Wave Two device with up to 503 qubits. By using random spin glass instances as a benchmark, we found no evidence of quantum speedup when the entire data set is considered and obtained inconclusive results when comparing subsets of instances on an instance-by-instance basis. Our results do not rule out the possibility of speedup for other classes of problems and illustrate the subtle nature of the quantum speedup question. PMID:25061205

  15. Prospects for quantum computation with trapped ions

    SciTech Connect

    Hughes, R.J.; James, D.F.V.

    1997-12-31

    Over the past decade information theory has been generalized to allow binary data to be represented by two-state quantum mechanical systems. (A single two-level system has come to be known as a qubit in this context.) The additional freedom introduced into information physics with quantum systems has opened up a variety of capabilities that go well beyond those of conventional information. For example, quantum cryptography allows two parties to generate a secret key even in the presence of eavesdropping. But perhaps the most remarkable capabilities have been predicted in the field of quantum computation. Here, a brief survey of the requirements for quantum computational hardware, and an overview of the in trap quantum computation project at Los Alamos are presented. The physical limitations to quantum computation with trapped ions are discussed.

  16. Quantum Computational Logics and Possible Applications

    NASA Astrophysics Data System (ADS)

    Chiara, Maria Luisa Dalla; Giuntini, Roberto; Leporini, Roberto; di Francia, Giuliano Toraldo

    2008-01-01

    In quantum computational logics meanings of formulas are identified with quantum information quantities: systems of qubits or, more generally, mixtures of systems of qubits. We consider two kinds of quantum computational semantics: (1) a compositional semantics, where the meaning of a compound formula is determined by the meanings of its parts; (2) a holistic semantics, which makes essential use of the characteristic “holistic” features of the quantum-theoretic formalism. The compositional and the holistic semantics turn out to characterize the same logic. In this framework, one can introduce the notion of quantum-classical truth table, which corresponds to the most natural way for a quantum computer to calculate classical tautologies. Quantum computational logics can be applied to investigate different kinds of semantic phenomena where holistic, contextual and gestaltic patterns play an essential role (from natural languages to musical compositions).

  17. Molecular Realizations of Quantum Computing 2007

    NASA Astrophysics Data System (ADS)

    Nakahara, Mikio; Ota, Yukihiro; Rahimi, Robabeh; Kondo, Yasushi; Tada-Umezaki, Masahito

    2009-06-01

    Liquid-state NMR quantum computer: working principle and some examples / Y. Kondo -- Flux qubits, tunable coupling and beyond / A. O. Niskanen -- Josephson phase qubits, and quantum communication via a resonant cavity / M. A. Sillanpää -- Quantum computing using pulse-based electron-nuclear double resonance (ENDOR): molecular spin-qubits / K. Sato ... [et al.] -- Fullerene C[symbol]: a possible molecular quantum computer / T. Wakabayashi -- Molecular magnets for quantum computation / T. Kuroda -- Errors in a plausible scheme of quantum gates in Kane's model / Y. Ota -- Yet another formulation for quantum simultaneous noncooperative bimatrix games / A. SaiToh, R. Rahimi, M. Nakahara -- Continuous-variable teleportation of single-photon states and an accidental cloning of a photonic qubit in two-channel teleportation / T. Ide.

  18. Some Thoughts Regarding Practical Quantum Computing

    NASA Astrophysics Data System (ADS)

    Ghoshal, Debabrata; Gomez, Richard; Lanzagorta, Marco; Uhlmann, Jeffrey

    2006-03-01

    Quantum computing has become an important area of research in computer science because of its potential to provide more efficient algorithmic solutions to certain problems than are possible with classical computing. The ability of performing parallel operations over an exponentially large computational space has proved to be the main advantage of the quantum computing model. In this regard, we are particularly interested in the potential applications of quantum computers to enhance real software systems of interest to the defense, industrial, scientific and financial communities. However, while much has been written in popular and scientific literature about the benefits of the quantum computational model, several of the problems associated to the practical implementation of real-life complex software systems in quantum computers are often ignored. In this presentation we will argue that practical quantum computation is not as straightforward as commonly advertised, even if the technological problems associated to the manufacturing and engineering of large-scale quantum registers were solved overnight. We will discuss some of the frequently overlooked difficulties that plague quantum computing in the areas of memories, I/O, addressing schemes, compilers, oracles, approximate information copying, logical debugging, error correction and fault-tolerant computing protocols.

  19. The Heisenberg representation of quantum computers

    SciTech Connect

    Gottesman, D.

    1998-06-24

    Since Shor`s discovery of an algorithm to factor numbers on a quantum computer in polynomial time, quantum computation has become a subject of immense interest. Unfortunately, one of the key features of quantum computers--the difficulty of describing them on classical computers--also makes it difficult to describe and understand precisely what can be done with them. A formalism describing the evolution of operators rather than states has proven extremely fruitful in understanding an important class of quantum operations. States used in error correction and certain communication protocols can be described by their stabilizer, a group of tensor products of Pauli matrices. Even this simple group structure is sufficient to allow a rich range of quantum effects, although it falls short of the full power of quantum computation.

  20. Surface code quantum computing by lattice surgery

    NASA Astrophysics Data System (ADS)

    Horsman, Clare; Fowler, Austin G.; Devitt, Simon; Van Meter, Rodney

    2012-12-01

    In recent years, surface codes have become a leading method for quantum error correction in theoretical large-scale computational and communications architecture designs. Their comparatively high fault-tolerant thresholds and their natural two-dimensional nearest-neighbour (2DNN) structure make them an obvious choice for large scale designs in experimentally realistic systems. While fundamentally based on the toric code of Kitaev, there are many variants, two of which are the planar- and defect-based codes. Planar codes require fewer qubits to implement (for the same strength of error correction), but are restricted to encoding a single qubit of information. Interactions between encoded qubits are achieved via transversal operations, thus destroying the inherent 2DNN nature of the code. In this paper we introduce a new technique enabling the coupling of two planar codes without transversal operations, maintaining the 2DNN of the encoded computer. Our lattice surgery technique comprises splitting and merging planar code surfaces, and enables us to perform universal quantum computation (including magic state injection) while removing the need for braided logic in a strictly 2DNN design, and hence reduces the overall qubit resources for logic operations. Those resources are further reduced by the use of a rotated lattice for the planar encoding. We show how lattice surgery allows us to distribute encoded GHZ states in a more direct (and overhead friendly) manner, and how a demonstration of an encoded CNOT between two distance-3 logical states is possible with 53 physical qubits, half of that required in any other known construction in 2D.

  1. Architecture dependence of photon antibunching in cavity quantum electrodynamics

    NASA Astrophysics Data System (ADS)

    Bradford, Matthew; Shen, Jung-Tsung

    2015-08-01

    We investigate numerically the architecture dependence of the characteristics of antibunched photons generated in cavity quantum electrodynamic systems. We show that the quality of antibunching [the smallness of the second-order intensity correlation function at zero time g(2 )(0 ) ] and the generation efficiency significantly depend on the configurations: the arrangements of single-mode optical cavities and waveguides. We found that for certain class of architecture, when the Jaynes-Cummings system (the atom-cavity system) couples to two terminated waveguides, there exists a fundamental tradeoff between high transmission and low g(2 )(0 ) , and is sensitive to dissipation. We further show that optimal antibunching can be achieved in two alternative cavity quantum electrodynamic configurations operating in the dissipatively weak coupling regime such that the two-photon transmission can be two orders of magnitude higher for the same g(2 )(0 ) .

  2. Performance Analysis of Cloud Computing Architectures Using Discrete Event Simulation

    NASA Technical Reports Server (NTRS)

    Stocker, John C.; Golomb, Andrew M.

    2011-01-01

    Cloud computing offers the economic benefit of on-demand resource allocation to meet changing enterprise computing needs. However, the flexibility of cloud computing is disadvantaged when compared to traditional hosting in providing predictable application and service performance. Cloud computing relies on resource scheduling in a virtualized network-centric server environment, which makes static performance analysis infeasible. We developed a discrete event simulation model to evaluate the overall effectiveness of organizations in executing their workflow in traditional and cloud computing architectures. The two part model framework characterizes both the demand using a probability distribution for each type of service request as well as enterprise computing resource constraints. Our simulations provide quantitative analysis to design and provision computing architectures that maximize overall mission effectiveness. We share our analysis of key resource constraints in cloud computing architectures and findings on the appropriateness of cloud computing in various applications.

  3. Quantum Computer Games: Schrodinger Cat and Hounds

    ERIC Educational Resources Information Center

    Gordon, Michal; Gordon, Goren

    2012-01-01

    The quantum computer game "Schrodinger cat and hounds" is the quantum extension of the well-known classical game fox and hounds. Its main objective is to teach the unique concepts of quantum mechanics in a fun way. "Schrodinger cat and hounds" demonstrates the effects of superposition, destructive and constructive interference, measurements and…

  4. Computational quantum-classical boundary of noisy commuting quantum circuits

    PubMed Central

    Fujii, Keisuke; Tamate, Shuhei

    2016-01-01

    It is often said that the transition from quantum to classical worlds is caused by decoherence originated from an interaction between a system of interest and its surrounding environment. Here we establish a computational quantum-classical boundary from the viewpoint of classical simulatability of a quantum system under decoherence. Specifically, we consider commuting quantum circuits being subject to decoherence. Or equivalently, we can regard them as measurement-based quantum computation on decohered weighted graph states. To show intractability of classical simulation in the quantum side, we utilize the postselection argument and crucially strengthen it by taking noise effect into account. Classical simulatability in the classical side is also shown constructively by using both separable criteria in a projected-entangled-pair-state picture and the Gottesman-Knill theorem for mixed state Clifford circuits. We found that when each qubit is subject to a single-qubit complete-positive-trace-preserving noise, the computational quantum-classical boundary is sharply given by the noise rate required for the distillability of a magic state. The obtained quantum-classical boundary of noisy quantum dynamics reveals a complexity landscape of controlled quantum systems. This paves a way to an experimentally feasible verification of quantum mechanics in a high complexity limit beyond classically simulatable region. PMID:27189039

  5. Computational quantum-classical boundary of noisy commuting quantum circuits

    NASA Astrophysics Data System (ADS)

    Fujii, Keisuke; Tamate, Shuhei

    2016-05-01

    It is often said that the transition from quantum to classical worlds is caused by decoherence originated from an interaction between a system of interest and its surrounding environment. Here we establish a computational quantum-classical boundary from the viewpoint of classical simulatability of a quantum system under decoherence. Specifically, we consider commuting quantum circuits being subject to decoherence. Or equivalently, we can regard them as measurement-based quantum computation on decohered weighted graph states. To show intractability of classical simulation in the quantum side, we utilize the postselection argument and crucially strengthen it by taking noise effect into account. Classical simulatability in the classical side is also shown constructively by using both separable criteria in a projected-entangled-pair-state picture and the Gottesman-Knill theorem for mixed state Clifford circuits. We found that when each qubit is subject to a single-qubit complete-positive-trace-preserving noise, the computational quantum-classical boundary is sharply given by the noise rate required for the distillability of a magic state. The obtained quantum-classical boundary of noisy quantum dynamics reveals a complexity landscape of controlled quantum systems. This paves a way to an experimentally feasible verification of quantum mechanics in a high complexity limit beyond classically simulatable region.

  6. Computational quantum-classical boundary of noisy commuting quantum circuits.

    PubMed

    Fujii, Keisuke; Tamate, Shuhei

    2016-01-01

    It is often said that the transition from quantum to classical worlds is caused by decoherence originated from an interaction between a system of interest and its surrounding environment. Here we establish a computational quantum-classical boundary from the viewpoint of classical simulatability of a quantum system under decoherence. Specifically, we consider commuting quantum circuits being subject to decoherence. Or equivalently, we can regard them as measurement-based quantum computation on decohered weighted graph states. To show intractability of classical simulation in the quantum side, we utilize the postselection argument and crucially strengthen it by taking noise effect into account. Classical simulatability in the classical side is also shown constructively by using both separable criteria in a projected-entangled-pair-state picture and the Gottesman-Knill theorem for mixed state Clifford circuits. We found that when each qubit is subject to a single-qubit complete-positive-trace-preserving noise, the computational quantum-classical boundary is sharply given by the noise rate required for the distillability of a magic state. The obtained quantum-classical boundary of noisy quantum dynamics reveals a complexity landscape of controlled quantum systems. This paves a way to an experimentally feasible verification of quantum mechanics in a high complexity limit beyond classically simulatable region. PMID:27189039

  7. Innovative architectures for dense multi-microprocessor computers

    NASA Technical Reports Server (NTRS)

    Donaldson, Thomas; Doty, Karl; Engle, Steven W.; Larson, Robert E.; O'Reilly, John G.

    1988-01-01

    The results of a Phase I Small Business Innovative Research (SBIR) project performed for the NASA Langley Computational Structural Mechanics Group are described. The project resulted in the identification of a family of chordal-ring interconnection architectures with excellent potential to serve as the basis for new multimicroprocessor (MMP) computers. The paper presents examples of how computational algorithms from structural mechanics can be efficiently implemented on the chordal-ring architecture.

  8. Digital quantum simulators in a scalable architecture of hybrid spin-photon qubits

    NASA Astrophysics Data System (ADS)

    Chiesa, Alessandro; Santini, Paolo; Gerace, Dario; Raftery, James; Houck, Andrew A.; Carretta, Stefano

    2015-11-01

    Resolving quantum many-body problems represents one of the greatest challenges in physics and physical chemistry, due to the prohibitively large computational resources that would be required by using classical computers. A solution has been foreseen by directly simulating the time evolution through sequences of quantum gates applied to arrays of qubits, i.e. by implementing a digital quantum simulator. Superconducting circuits and resonators are emerging as an extremely promising platform for quantum computation architectures, but a digital quantum simulator proposal that is straightforwardly scalable, universal, and realizable with state-of-the-art technology is presently lacking. Here we propose a viable scheme to implement a universal quantum simulator with hybrid spin-photon qubits in an array of superconducting resonators, which is intrinsically scalable and allows for local control. As representative examples we consider the transverse-field Ising model, a spin-1 Hamiltonian, and the two-dimensional Hubbard model and we numerically simulate the scheme by including the main sources of decoherence.

  9. Digital quantum simulators in a scalable architecture of hybrid spin-photon qubits

    PubMed Central

    Chiesa, Alessandro; Santini, Paolo; Gerace, Dario; Raftery, James; Houck, Andrew A.; Carretta, Stefano

    2015-01-01

    Resolving quantum many-body problems represents one of the greatest challenges in physics and physical chemistry, due to the prohibitively large computational resources that would be required by using classical computers. A solution has been foreseen by directly simulating the time evolution through sequences of quantum gates applied to arrays of qubits, i.e. by implementing a digital quantum simulator. Superconducting circuits and resonators are emerging as an extremely promising platform for quantum computation architectures, but a digital quantum simulator proposal that is straightforwardly scalable, universal, and realizable with state-of-the-art technology is presently lacking. Here we propose a viable scheme to implement a universal quantum simulator with hybrid spin-photon qubits in an array of superconducting resonators, which is intrinsically scalable and allows for local control. As representative examples we consider the transverse-field Ising model, a spin-1 Hamiltonian, and the two-dimensional Hubbard model and we numerically simulate the scheme by including the main sources of decoherence. PMID:26563516

  10. Digital quantum simulators in a scalable architecture of hybrid spin-photon qubits.

    PubMed

    Chiesa, Alessandro; Santini, Paolo; Gerace, Dario; Raftery, James; Houck, Andrew A; Carretta, Stefano

    2015-01-01

    Resolving quantum many-body problems represents one of the greatest challenges in physics and physical chemistry, due to the prohibitively large computational resources that would be required by using classical computers. A solution has been foreseen by directly simulating the time evolution through sequences of quantum gates applied to arrays of qubits, i.e. by implementing a digital quantum simulator. Superconducting circuits and resonators are emerging as an extremely promising platform for quantum computation architectures, but a digital quantum simulator proposal that is straightforwardly scalable, universal, and realizable with state-of-the-art technology is presently lacking. Here we propose a viable scheme to implement a universal quantum simulator with hybrid spin-photon qubits in an array of superconducting resonators, which is intrinsically scalable and allows for local control. As representative examples we consider the transverse-field Ising model, a spin-1 Hamiltonian, and the two-dimensional Hubbard model and we numerically simulate the scheme by including the main sources of decoherence. PMID:26563516

  11. Task scheduling in dataflow computer architectures

    NASA Technical Reports Server (NTRS)

    Katsinis, Constantine

    1994-01-01

    Dataflow computers provide a platform for the solution of a large class of computational problems, which includes digital signal processing and image processing. Many typical applications are represented by a set of tasks which can be repetitively executed in parallel as specified by an associated dataflow graph. Research in this area aims to model these architectures, develop scheduling procedures, and predict the transient and steady state performance. Researchers at NASA have created a model and developed associated software tools which are capable of analyzing a dataflow graph and predicting its runtime performance under various resource and timing constraints. These models and tools were extended and used in this work. Experiments using these tools revealed certain properties of such graphs that require further study. Specifically, the transient behavior at the beginning of the execution of a graph can have a significant effect on the steady state performance. Transformation and retiming of the application algorithm and its initial conditions can produce a different transient behavior and consequently different steady state performance. The effect of such transformations on the resource requirements or under resource constraints requires extensive study. Task scheduling to obtain maximum performance (based on user-defined criteria), or to satisfy a set of resource constraints, can also be significantly affected by a transformation of the application algorithm. Since task scheduling is performed by heuristic algorithms, further research is needed to determine if new scheduling heuristics can be developed that can exploit such transformations. This work has provided the initial development for further long-term research efforts. A simulation tool was completed to provide insight into the transient and steady state execution of a dataflow graph. A set of scheduling algorithms was completed which can operate in conjunction with the modeling and performance tools

  12. Geometry of Quantum Computation with Qudits

    PubMed Central

    Luo, Ming-Xing; Chen, Xiu-Bo; Yang, Yi-Xian; Wang, Xiaojun

    2014-01-01

    The circuit complexity of quantum qubit system evolution as a primitive problem in quantum computation has been discussed widely. We investigate this problem in terms of qudit system. Using the Riemannian geometry the optimal quantum circuits are equivalent to the geodetic evolutions in specially curved parametrization of SU(dn). And the quantum circuit complexity is explicitly dependent of controllable approximation error bound. PMID:24509710

  13. Determining Ramsey numbers on a quantum computer

    NASA Astrophysics Data System (ADS)

    Wang, Hefeng

    2016-03-01

    We present a quantum algorithm for computing the Ramsey numbers whose computational complexity grows superexponentially with the number of vertices of a graph on a classical computer. The problem is mapped to a decision problem on a quantum computer, and a probe qubit is coupled to a register that represents the problem and detects the energy levels of the problem Hamiltonian. The decision problem is solved by detecting the decay dynamics of the probe qubit.

  14. Multithreaded processor architecture for parallel symbolic computation. Technical report

    SciTech Connect

    Fujita, T.

    1987-09-01

    This paper describes the Multilisp Architecture for Symbolic Applications (MASA), which is a multithreaded processor architecture for parallel symbolic computation with various features intended for effective Multilisp program execution. The principal mechanisms exploited for this processor are multiple contexts, interleaved pipeline execution from separate instruction streams, and synchronization based on a bit in each memory cell. The tagged architecture approach is taken for Lisp program execution, and trap conditions are provided for future object manipulation and garbage collection.

  15. Pipeline and parallel architectures for computer communication systems

    SciTech Connect

    Reddi, A.V.

    1983-01-01

    Various existing communication precessor systems (CPSS) at different nodes in computer communication systems (CCSS) are reviewed for distributed processing systems. To meet the increasing load of messages, pipeline and parallel architectures are suggested in CPSS. Finally, pipeline, array, multi and multiple-processor architectures and their advantages in CPSS for CCSS are presented and analysed, and their performances are compared with the performance of uniprocessor architecture. 19 references.

  16. Quantum computation mediated by ancillary qudits and spin coherent states

    NASA Astrophysics Data System (ADS)

    Proctor, Timothy J.; Dooley, Shane; Kendon, Viv

    2015-01-01

    Models of universal quantum computation in which the required interactions between register (computational) qubits are mediated by some ancillary system are highly relevant to experimental realizations of a quantum computer. We introduce such a universal model that employs a d -dimensional ancillary qudit. The ancilla-register interactions take the form of controlled displacements operators, with a displacement operator defined on the periodic and discrete lattice phase space of a qudit. We show that these interactions can implement controlled phase gates on the register by utilizing geometric phases that are created when closed loops are traversed in this phase space. The extra degrees of freedom of the ancilla can be harnessed to reduce the number of operations required for certain gate sequences. In particular, we see that the computational advantages of the quantum bus (qubus) architecture, which employs a field-mode ancilla, are also applicable to this model. We then explore an alternative ancilla-mediated model which employs a spin ensemble as the ancillary system and again the interactions with the register qubits are via controlled displacement operators, with a displacement operator defined on the Bloch sphere phase space of the spin coherent states of the ensemble. We discuss the computational advantages of this model and its relationship with the qubus architecture.

  17. Experimental demonstration of deterministic one-way quantum computation on a NMR quantum computer

    SciTech Connect

    Ju, Chenyong; Zhu Jing; Peng Xinhua; Chong Bo; Zhou Xianyi; Du Jiangfeng

    2010-01-15

    One-way quantum computing is an important and novel approach to quantum computation. By exploiting the existing particle-particle interactions, we report an experimental realization of the complete process of deterministic one-way quantum Deutsch-Josza algorithm in NMR, including graph state preparation, single-qubit measurements, and feed-forward corrections. The findings in our experiment may shed light on the future scalable one-way quantum computation.

  18. Universal Matchgate Quantum Computing With Cold Polar Molecules

    NASA Astrophysics Data System (ADS)

    Herrera, Felipe

    2015-03-01

    Polar molecules in optical lattices are attractive for quantum simulation and computation due to the ability to implement a variety of spin-lattice models using static, microwave and optical fields to engineer the long-range dipolar interaction between molecular qubits. Quantum simulation of spin models requires global control over the molecular ensemble, while quantum computation requires control of individual molecules with sub-wavelength resolution. In this talk, we describe the implementation of a matchgate quantum processor with an ensemble of polar molecules in an optical lattice. The scheme uses few-body qubit encoding and sequential control of two-body dipolar interactions over small plaquetes on a square lattice to perform universal quantum computing without single-site addressing. Effective spin-spin interactions with matchgate symmetry between open-shell polar molecules (e.g., SrF, OH) are driven by two infrared control pulses in the absence of static electric fields. The resulting matchgates are robust with respect to realistic imperfections in the driving fields and lattice trapping. Applications of the architecture for the simulation of interacting fermions in quantum chemistry are discussed, considering an imperfect lattice filling.

  19. A heterogeneous hierarchical architecture for real-time computing

    SciTech Connect

    Skroch, D.A.; Fornaro, R.J.

    1988-12-01

    The need for high-speed data acquisition and control algorithms has prompted continued research in the area of multiprocessor systems and related programming techniques. The result presented here is a unique hardware and software architecture for high-speed real-time computer systems. The implementation of a prototype of this architecture has required the integration of architecture, operating systems and programming languages into a cohesive unit. This report describes a Heterogeneous Hierarchial Architecture for Real-Time (H{sup 2} ART) and system software for program loading and interprocessor communication.

  20. A Simple Physical Optics Algorithm Perfect for Parallel Computing Architecture

    NASA Technical Reports Server (NTRS)

    Imbriale, W. A.; Cwik, T.

    1994-01-01

    A reflector antenna computer program based upon a simple discreet approximation of the radiation integral has proven to be extremely easy to adapt to the parallel computing architecture of the modest number of large-gain computing elements such as are used in the Intel iPSC and Touchstone Delta parallel machines.

  1. Graph isomorphism and adiabatic quantum computing

    NASA Astrophysics Data System (ADS)

    Gaitan, Frank; Clark, Lane

    2014-02-01

    In the graph isomorphism (GI) problem two N-vertex graphs G and G' are given and the task is to determine whether there exists a permutation of the vertices of G that preserves adjacency and transforms G →G'. If yes, then G and G' are said to be isomorphic; otherwise they are nonisomorphic. The GI problem is an important problem in computer science and is thought to be of comparable difficulty to integer factorization. In this paper we present a quantum algorithm that solves arbitrary instances of GI and which also provides an approach to determining all automorphisms of a given graph. We show how the GI problem can be converted to a combinatorial optimization problem that can be solved using adiabatic quantum evolution. We numerically simulate the algorithm's quantum dynamics and show that it correctly (i) distinguishes nonisomorphic graphs; (ii) recognizes isomorphic graphs and determines the permutation(s) that connect them; and (iii) finds the automorphism group of a given graph G. We then discuss the GI quantum algorithm's experimental implementation, and close by showing how it can be leveraged to give a quantum algorithm that solves arbitrary instances of the NP-complete subgraph isomorphism problem. The computational complexity of an adiabatic quantum algorithm is largely determined by the minimum energy gap Δ (N) separating the ground and first-excited states in the limit of large problem size N ≫1. Calculating Δ (N) in this limit is a fundamental open problem in adiabatic quantum computing, and so it is not possible to determine the computational complexity of adiabatic quantum algorithms in general, nor consequently, of the specific adiabatic quantum algorithms presented here. Adiabatic quantum computing has been shown to be equivalent to the circuit model of quantum computing, and so development of adiabatic quantum algorithms continues to be of great interest.

  2. Universal quantum computation with weakly integral anyons

    NASA Astrophysics Data System (ADS)

    Cui, Shawn X.; Hong, Seung-Moon; Wang, Zhenghan

    2015-08-01

    Harnessing non-abelian statistics of anyons to perform quantum computational tasks is getting closer to reality. While the existence of universal anyons by braiding alone such as the Fibonacci anyon is theoretically a possibility, accessible anyons with current technology all belong to a class that is called weakly integral—anyons whose squared quantum dimensions are integers. We analyze the computational power of the first non-abelian anyon system with only integral quantum dimensions—, the quantum double of . Since all anyons in have finite images of braid group representations, they cannot be universal for quantum computation by braiding alone. Based on our knowledge of the images of the braid group representations, we set up three qutrit computational models. Supplementing braidings with some measurements and ancillary states, we find a universal gate set for each model.

  3. Video Encryption and Decryption on Quantum Computers

    NASA Astrophysics Data System (ADS)

    Yan, Fei; Iliyasu, Abdullah M.; Venegas-Andraca, Salvador E.; Yang, Huamin

    2015-08-01

    A method for video encryption and decryption on quantum computers is proposed based on color information transformations on each frame encoding the content of the encoding the content of the video. The proposed method provides a flexible operation to encrypt quantum video by means of the quantum measurement in order to enhance the security of the video. To validate the proposed approach, a tetris tile-matching puzzle game video is utilized in the experimental simulations. The results obtained suggest that the proposed method enhances the security and speed of quantum video encryption and decryption, both properties required for secure transmission and sharing of video content in quantum communication.

  4. Numerical computation for teaching quantum statistics

    NASA Astrophysics Data System (ADS)

    Price, Tyson; Swendsen, Robert H.

    2013-11-01

    The study of ideal quantum gases reveals surprising quantum effects that can be observed in macroscopic systems. The properties of bosons are particularly unusual because a macroscopic number of particles can occupy a single quantum state. We describe a computational approach that supplements the usual analytic derivations applicable in the thermodynamic limit. The approach involves directly summing over the quantum states for finite systems and avoids the need for doing difficult integrals. The results display the unusual behavior of quantum gases even for relatively small systems.

  5. Quantum Monte Carlo Endstation for Petascale Computing

    SciTech Connect

    Lubos Mitas

    2011-01-26

    NCSU research group has been focused on accomplising the key goals of this initiative: establishing new generation of quantum Monte Carlo (QMC) computational tools as a part of Endstation petaflop initiative for use at the DOE ORNL computational facilities and for use by computational electronic structure community at large; carrying out high accuracy quantum Monte Carlo demonstration projects in application of these tools to the forefront electronic structure problems in molecular and solid systems; expanding the impact of QMC methods and approaches; explaining and enhancing the impact of these advanced computational approaches. In particular, we have developed quantum Monte Carlo code (QWalk, www.qwalk.org) which was significantly expanded and optimized using funds from this support and at present became an actively used tool in the petascale regime by ORNL researchers and beyond. These developments have been built upon efforts undertaken by the PI's group and collaborators over the period of the last decade. The code was optimized and tested extensively on a number of parallel architectures including petaflop ORNL Jaguar machine. We have developed and redesigned a number of code modules such as evaluation of wave functions and orbitals, calculations of pfaffians and introduction of backflow coordinates together with overall organization of the code and random walker distribution over multicore architectures. We have addressed several bottlenecks such as load balancing and verified efficiency and accuracy of the calculations with the other groups of the Endstation team. The QWalk package contains about 50,000 lines of high quality object-oriented C++ and includes also interfaces to data files from other conventional electronic structure codes such as Gamess, Gaussian, Crystal and others. This grant supported PI for one month during summers, a full-time postdoc and partially three graduate students over the period of the grant duration, it has resulted in 13

  6. Integrated computer control system architectural overview

    SciTech Connect

    Van Arsdall, P.

    1997-06-18

    This overview introduces the NIF Integrated Control System (ICCS) architecture. The design is abstract to allow the construction of many similar applications from a common framework. This summary lays the essential foundation for understanding the model-based engineering approach used to execute the design.

  7. Quantum Computation Using Optically Coupled Quantum Dot Arrays

    NASA Technical Reports Server (NTRS)

    Pradhan, Prabhakar; Anantram, M. P.; Wang, K. L.; Roychowhury, V. P.; Saini, Subhash (Technical Monitor)

    1998-01-01

    A solid state model for quantum computation has potential advantages in terms of the ease of fabrication, characterization, and integration. The fundamental requirements for a quantum computer involve the realization of basic processing units (qubits), and a scheme for controlled switching and coupling among the qubits, which enables one to perform controlled operations on qubits. We propose a model for quantum computation based on optically coupled quantum dot arrays, which is computationally similar to the atomic model proposed by Cirac and Zoller. In this model, individual qubits are comprised of two coupled quantum dots, and an array of these basic units is placed in an optical cavity. Switching among the states of the individual units is done by controlled laser pulses via near field interaction using the NSOM technology. Controlled rotations involving two or more qubits are performed via common cavity mode photon. We have calculated critical times, including the spontaneous emission and switching times, and show that they are comparable to the best times projected for other proposed models of quantum computation. We have also shown the feasibility of accessing individual quantum dots using the NSOM technology by calculating the photon density at the tip, and estimating the power necessary to perform the basic controlled operations. We are currently in the process of estimating the decoherence times for this system; however, we have formulated initial arguments which seem to indicate that the decoherence times will be comparable, if not longer, than many other proposed models.

  8. Rate-loss analysis of an efficient quantum repeater architecture

    NASA Astrophysics Data System (ADS)

    Guha, Saikat; Krovi, Hari; Fuchs, Christopher A.; Dutton, Zachary; Slater, Joshua A.; Simon, Christoph; Tittel, Wolfgang

    2015-08-01

    We analyze an entanglement-based quantum key distribution (QKD) architecture that uses a linear chain of quantum repeaters employing photon-pair sources, spectral-multiplexing, linear-optic Bell-state measurements, multimode quantum memories, and classical-only error correction. Assuming perfect sources, we find an exact expression for the secret-key rate, and an analytical description of how errors propagate through the repeater chain, as a function of various loss-and-noise parameters of the devices. We show via an explicit analytical calculation, which separately addresses the effects of the principle nonidealities, that this scheme achieves a secret-key rate that surpasses the Takeoka-Guha-Wilde bound—a recently found fundamental limit to the rate-vs-loss scaling achievable by any QKD protocol over a direct optical link—thereby providing one of the first rigorous proofs of the efficacy of a repeater protocol. We explicitly calculate the end-to-end shared noisy quantum state generated by the repeater chain, which could be useful for analyzing the performance of other non-QKD quantum protocols that require establishing long-distance entanglement. We evaluate that shared state's fidelity and the achievable entanglement-distillation rate, as a function of the number of repeater nodes, total range, and various loss-and-noise parameters of the system. We extend our theoretical analysis to encompass sources with nonzero two-pair-emission probability, using an efficient exact numerical evaluation of the quantum state propagation and measurements. We expect our results to spur formal rate-loss analysis of other repeater protocols and also to provide useful abstractions to seed analyses of quantum networks of complex topologies.

  9. A scalable quantum computer with ions in an array of microtraps

    PubMed

    Cirac; Zoller

    2000-04-01

    Quantum computers require the storage of quantum information in a set of two-level systems (called qubits), the processing of this information using quantum gates and a means of final readout. So far, only a few systems have been identified as potentially viable quantum computer models--accurate quantum control of the coherent evolution is required in order to realize gate operations, while at the same time decoherence must be avoided. Examples include quantum optical systems (such as those utilizing trapped ions or neutral atoms, cavity quantum electrodynamics and nuclear magnetic resonance) and solid state systems (using nuclear spins, quantum dots and Josephson junctions). The most advanced candidates are the quantum optical and nuclear magnetic resonance systems, and we expect that they will allow quantum computing with about ten qubits within the next few years. This is still far from the numbers required for useful applications: for example, the factorization of a 200-digit number requires about 3,500 qubits, rising to 100,000 if error correction is implemented. Scalability of proposed quantum computer architectures to many qubits is thus of central importance. Here we propose a model for an ion trap quantum computer that combines scalability (a feature usually associated with solid state proposals) with the advantages of quantum optical systems (in particular, quantum control and long decoherence times). PMID:10766235

  10. Differential geometric treewidth estimation in adiabatic quantum computation

    NASA Astrophysics Data System (ADS)

    Wang, Chi; Jonckheere, Edmond; Brun, Todd

    2016-07-01

    The D-Wave adiabatic quantum computing platform is designed to solve a particular class of problems—the Quadratic Unconstrained Binary Optimization (QUBO) problems. Due to the particular "Chimera" physical architecture of the D-Wave chip, the logical problem graph at hand needs an extra process called minor embedding in order to be solvable on the D-Wave architecture. The latter problem is itself NP-hard. In this paper, we propose a novel polynomial-time approximation to the closely related treewidth based on the differential geometric concept of Ollivier-Ricci curvature. The latter runs in polynomial time and thus could significantly reduce the overall complexity of determining whether a QUBO problem is minor embeddable, and thus solvable on the D-Wave architecture.

  11. Quantum computer simulation using the CUDA programming model

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Eladio; Romero, Sergio; Trenas, María A.; Zapata, Emilio L.

    2010-02-01

    Quantum computing emerges as a field that captures a great theoretical interest. Its simulation represents a problem with high memory and computational requirements which makes advisable the use of parallel platforms. In this work we deal with the simulation of an ideal quantum computer on the Compute Unified Device Architecture (CUDA), as such a problem can benefit from the high computational capacities of Graphics Processing Units (GPU). After all, modern GPUs are becoming very powerful computational architectures which is causing a growing interest in their application for general purpose. CUDA provides an execution model oriented towards a more general exploitation of the GPU allowing to use it as a massively parallel SIMT (Single-Instruction Multiple-Thread) multiprocessor. A simulator that takes into account memory reference locality issues is proposed, showing that the challenge of achieving a high performance depends strongly on the explicit exploitation of memory hierarchy. Several strategies have been experimentally evaluated obtaining good performance results in comparison with conventional platforms.

  12. Conceptual aspects of geometric quantum computation

    NASA Astrophysics Data System (ADS)

    Sjöqvist, Erik; Azimi Mousolou, Vahid; Canali, Carlo M.

    2016-07-01

    Geometric quantum computation is the idea that geometric phases can be used to implement quantum gates, i.e., the basic elements of the Boolean network that forms a quantum computer. Although originally thought to be limited to adiabatic evolution, controlled by slowly changing parameters, this form of quantum computation can as well be realized at high speed by using nonadiabatic schemes. Recent advances in quantum gate technology have allowed for experimental demonstrations of different types of geometric gates in adiabatic and nonadiabatic evolution. Here, we address some conceptual issues that arise in the realizations of geometric gates. We examine the appearance of dynamical phases in quantum evolution and point out that not all dynamical phases need to be compensated for in geometric quantum computation. We delineate the relation between Abelian and non-Abelian geometric gates and find an explicit physical example where the two types of gates coincide. We identify differences and similarities between adiabatic and nonadiabatic realizations of quantum computation based on non-Abelian geometric phases.

  13. Effective pure states for bulk quantum computation

    SciTech Connect

    Knill, E.; Chuang, I.; Laflamme, R.

    1997-11-01

    In bulk quantum computation one can manipulate a large number of indistinguishable quantum computers by parallel unitary operations and measure expectation values of certain observables with limited sensitivity. The initial state of each computer in the ensemble is known but not pure. Methods for obtaining effective pure input states by a series of manipulations have been described by Gershenfeld and Chuang (logical labeling) and Corey et al. (spatial averaging) for the case of quantum computation with nuclear magnetic resonance. We give a different technique called temporal averaging. This method is based on classical randomization, requires no ancilla qubits and can be implemented in nuclear magnetic resonance without using gradient fields. We introduce several temporal averaging algorithms suitable for both high temperature and low temperature bulk quantum computing and analyze the signal to noise behavior of each.

  14. Magnetic resonance force microscopy and a solid state quantum computer.

    SciTech Connect

    Pelekhov, D. V.; Martin, I.; Suter, A.; Reagor, D. W.; Hammel, P. C.

    2001-01-01

    A Quantum Computer (QC) is a device that utilizes the principles of Quantum Mechanics to perform computations. Such a machine would be capable of accomplishing tasks not achievable by means of any conventional digital computer, for instance factoring large numbers. Currently it appears that the QC architecture based on an array of spin quantum bits (qubits) embedded in a solid-state matrix is one of the most promising approaches to fabrication of a scalable QC. However, the fabrication and operation of a Solid State Quantum Computer (SSQC) presents very formidable challenges; primary amongst these are: (1) the characterization and control of the fabrication process of the device during its construction and (2) the readout of the computational result. Magnetic Resonance Force Microscopy (MRFM)--a novel scanning probe technique based on mechanical detection of magnetic resonance-provides an attractive means of addressing these requirements. The sensitivity of the MRFM significantly exceeds that of conventional magnetic resonance measurement methods, and it has the potential for single electron spin detection. Moreover, the MRFM is capable of true 3D subsurface imaging. These features will make MRFM an invaluable tool for the implementation of a spin-based QC. Here we present the general principles of MRFM operation, the current status of its development and indicate future directions for its improvement.

  15. Hyper-parallel photonic quantum computation with coupled quantum dots

    NASA Astrophysics Data System (ADS)

    Ren, Bao-Cang; Deng, Fu-Guo

    2014-04-01

    It is well known that a parallel quantum computer is more powerful than a classical one. So far, there are some important works about the construction of universal quantum logic gates, the key elements in quantum computation. However, they are focused on operating on one degree of freedom (DOF) of quantum systems. Here, we investigate the possibility of achieving scalable hyper-parallel quantum computation based on two DOFs of photon systems. We construct a deterministic hyper-controlled-not (hyper-CNOT) gate operating on both the spatial-mode and the polarization DOFs of a two-photon system simultaneously, by exploiting the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics (QED). This hyper-CNOT gate is implemented by manipulating the four qubits in the two DOFs of a two-photon system without auxiliary spatial modes or polarization modes. It reduces the operation time and the resources consumed in quantum information processing, and it is more robust against the photonic dissipation noise, compared with the integration of several cascaded CNOT gates in one DOF.

  16. Expandable computed-tomography architecture for nondestructive inspection

    NASA Astrophysics Data System (ADS)

    Agi, Iskender; Hurst, Paul J.; Current, K. W.

    1993-04-01

    The Radon transform and its inverse, commonly used for computed tomography (CT), are computationally burdensome for single processor computers. Since projection-based computations are easily executed in parallel, multiprocessor architectures have been proposed for high-speed operation. In this paper, we describe an architecture for a high-speed (30 MHz raster-scan image data rate), high accuracy (12-bits per pixel) computed-tomography system for use in non-destructive inspection system. This architecture reconstructs images from fan- or parallel-beam data using either single-pass or iterative reconstruction techniques. Our architecture uses a number of identical processor modules in a pipeline. Each processor module consists of memory for data storage, a commercially available digital signal processing (DSP) chip for filtering, and our custom IC which performs 450 million mathematical operations per second (MOPS). This architecture can reconstruct CT images as large as 1024 X 1024 pixels from a variety of image reconstruction algorithms. The details of the implementation and performance of our expandable architecture are discussed.

  17. Concatenated codes for fault tolerant quantum computing

    SciTech Connect

    Knill, E.; Laflamme, R.; Zurek, W.

    1995-05-01

    The application of concatenated codes to fault tolerant quantum computing is discussed. We have previously shown that for quantum memories and quantum communication, a state can be transmitted with error {epsilon} provided each gate has error at most c{epsilon}. We show how this can be used with Shor`s fault tolerant operations to reduce the accuracy requirements when maintaining states not currently participating in the computation. Viewing Shor`s fault tolerant operations as a method for reducing the error of operations, we give a concatenated implementation which promises to propagate the reduction hierarchically. This has the potential of reducing the accuracy requirements in long computations.

  18. A computational architecture for social agents

    SciTech Connect

    Bond, A.H.

    1996-12-31

    This article describes a new class of information-processing models for social agents. They axe derived from primate brain architecture, the processing in brain regions, the interactions among brain regions, and the social behavior of primates. In another paper, we have reviewed the neuroanatomical connections and functional involvements of cortical regions. We reviewed the evidence for a hierarchical architecture in the primate brain. By examining neuroanatomical evidence for connections among neural areas, we were able to establish anatomical regions and connections. We then examined evidence for specific functional involvements of the different neural axeas and found some support for hierarchical functioning, not only for the perception hierarchies but also for the planning and action hierarchy in the frontal lobes.

  19. Faster quantum chemistry simulation on fault-tolerant quantum computers

    NASA Astrophysics Data System (ADS)

    Cody Jones, N.; Whitfield, James D.; McMahon, Peter L.; Yung, Man-Hong; Van Meter, Rodney; Aspuru-Guzik, Alán; Yamamoto, Yoshihisa

    2012-11-01

    Quantum computers can in principle simulate quantum physics exponentially faster than their classical counterparts, but some technical hurdles remain. We propose methods which substantially improve the performance of a particular form of simulation, ab initio quantum chemistry, on fault-tolerant quantum computers; these methods generalize readily to other quantum simulation problems. Quantum teleportation plays a key role in these improvements and is used extensively as a computing resource. To improve execution time, we examine techniques for constructing arbitrary gates which perform substantially faster than circuits based on the conventional Solovay-Kitaev algorithm (Dawson and Nielsen 2006 Quantum Inform. Comput. 6 81). For a given approximation error ɛ, arbitrary single-qubit gates can be produced fault-tolerantly and using a restricted set of gates in time which is O(log ɛ) or O(log log ɛ) with sufficient parallel preparation of ancillas, constant average depth is possible using a method we call programmable ancilla rotations. Moreover, we construct and analyze efficient implementations of first- and second-quantized simulation algorithms using the fault-tolerant arbitrary gates and other techniques, such as implementing various subroutines in constant time. A specific example we analyze is the ground-state energy calculation for lithium hydride.

  20. Materials Frontiers to Empower Quantum Computing

    SciTech Connect

    Taylor, Antoinette Jane; Sarrao, John Louis; Richardson, Christopher

    2015-06-11

    This is an exciting time at the nexus of quantum computing and materials research. The materials frontiers described in this report represent a significant advance in electronic materials and our understanding of the interactions between the local material and a manufactured quantum state. Simultaneously, directed efforts to solve materials issues related to quantum computing provide an opportunity to control and probe the fundamental arrangement of matter that will impact all electronic materials. An opportunity exists to extend our understanding of materials functionality from electronic-grade to quantum-grade by achieving a predictive understanding of noise and decoherence in qubits and their origins in materials defects and environmental coupling. Realizing this vision systematically and predictively will be transformative for quantum computing and will represent a qualitative step forward in materials prediction and control.

  1. Superadiabatic Controlled Evolutions and Universal Quantum Computation

    PubMed Central

    Santos, Alan C.; Sarandy, Marcelo S.

    2015-01-01

    Adiabatic state engineering is a powerful technique in quantum information and quantum control. However, its performance is limited by the adiabatic theorem of quantum mechanics. In this scenario, shortcuts to adiabaticity, such as provided by the superadiabatic theory, constitute a valuable tool to speed up the adiabatic quantum behavior. Here, we propose a superadiabatic route to implement universal quantum computation. Our method is based on the realization of piecewise controlled superadiabatic evolutions. Remarkably, they can be obtained by simple time-independent counter-diabatic Hamiltonians. In particular, we discuss the implementation of fast rotation gates and arbitrary n-qubit controlled gates, which can be used to design different sets of universal quantum gates. Concerning the energy cost of the superadiabatic implementation, we show that it is dictated by the quantum speed limit, providing an upper bound for the corresponding adiabatic counterparts. PMID:26511064

  2. Superadiabatic Controlled Evolutions and Universal Quantum Computation

    NASA Astrophysics Data System (ADS)

    Santos, Alan C.; Sarandy, Marcelo S.

    2015-10-01

    Adiabatic state engineering is a powerful technique in quantum information and quantum control. However, its performance is limited by the adiabatic theorem of quantum mechanics. In this scenario, shortcuts to adiabaticity, such as provided by the superadiabatic theory, constitute a valuable tool to speed up the adiabatic quantum behavior. Here, we propose a superadiabatic route to implement universal quantum computation. Our method is based on the realization of piecewise controlled superadiabatic evolutions. Remarkably, they can be obtained by simple time-independent counter-diabatic Hamiltonians. In particular, we discuss the implementation of fast rotation gates and arbitrary n-qubit controlled gates, which can be used to design different sets of universal quantum gates. Concerning the energy cost of the superadiabatic implementation, we show that it is dictated by the quantum speed limit, providing an upper bound for the corresponding adiabatic counterparts.

  3. Reducing computational complexity of quantum correlations

    NASA Astrophysics Data System (ADS)

    Chanda, Titas; Das, Tamoghna; Sadhukhan, Debasis; Pal, Amit Kumar; SenDe, Aditi; Sen, Ujjwal

    2015-12-01

    We address the issue of reducing the resource required to compute information-theoretic quantum correlation measures such as quantum discord and quantum work deficit in two qubits and higher-dimensional systems. We show that determination of the quantum correlation measure is possible even if we utilize a restricted set of local measurements. We find that the determination allows us to obtain a closed form of quantum discord and quantum work deficit for several classes of states, with a low error. We show that the computational error caused by the constraint over the complete set of local measurements reduces fast with an increase in the size of the restricted set, implying usefulness of constrained optimization, especially with the increase of dimensions. We perform quantitative analysis to investigate how the error scales with the system size, taking into account a set of plausible constructions of the constrained set. Carrying out a comparative study, we show that the resource required to optimize quantum work deficit is usually higher than that required for quantum discord. We also demonstrate that minimization of quantum discord and quantum work deficit is easier in the case of two-qubit mixed states of fixed ranks and with positive partial transpose in comparison to the corresponding states having nonpositive partial transpose. Applying the methodology to quantum spin models, we show that the constrained optimization can be used with advantage in analyzing such systems in quantum information-theoretic language. For bound entangled states, we show that the error is significantly low when the measurements correspond to the spin observables along the three Cartesian coordinates, and thereby we obtain expressions of quantum discord and quantum work deficit for these bound entangled states.

  4. Is the Brain a Quantum Computer?

    ERIC Educational Resources Information Center

    Litt, Abninder; Eliasmith, Chris; Kroon, Frederick W.; Weinstein, Steven; Thagard, Paul

    2006-01-01

    We argue that computation via quantum mechanical processes is irrelevant to explaining how brains produce thought, contrary to the ongoing speculations of many theorists. First, quantum effects do not have the temporal properties required for neural information processing. Second, there are substantial physical obstacles to any organic…

  5. Iterated Gate Teleportation and Blind Quantum Computation

    NASA Astrophysics Data System (ADS)

    Pérez-Delgado, Carlos A.; Fitzsimons, Joseph F.

    2015-06-01

    Blind quantum computation allows a user to delegate a computation to an untrusted server while keeping the computation hidden. A number of recent works have sought to establish bounds on the communication requirements necessary to implement blind computation, and a bound based on the no-programming theorem of Nielsen and Chuang has emerged as a natural limiting factor. Here we show that this constraint only holds in limited scenarios, and show how to overcome it using a novel method of iterated gate teleportations. This technique enables drastic reductions in the communication required for distributed quantum protocols, extending beyond the blind computation setting. Applied to blind quantum computation, this technique offers significant efficiency improvements, and in some scenarios offers an exponential reduction in communication requirements.

  6. Iterated Gate Teleportation and Blind Quantum Computation.

    PubMed

    Pérez-Delgado, Carlos A; Fitzsimons, Joseph F

    2015-06-01

    Blind quantum computation allows a user to delegate a computation to an untrusted server while keeping the computation hidden. A number of recent works have sought to establish bounds on the communication requirements necessary to implement blind computation, and a bound based on the no-programming theorem of Nielsen and Chuang has emerged as a natural limiting factor. Here we show that this constraint only holds in limited scenarios, and show how to overcome it using a novel method of iterated gate teleportations. This technique enables drastic reductions in the communication required for distributed quantum protocols, extending beyond the blind computation setting. Applied to blind quantum computation, this technique offers significant efficiency improvements, and in some scenarios offers an exponential reduction in communication requirements. PMID:26196609

  7. A high performance parallel computing architecture for robust image features

    NASA Astrophysics Data System (ADS)

    Zhou, Renyan; Liu, Leibo; Wei, Shaojun

    2014-03-01

    A design of parallel architecture for image feature detection and description is proposed in this article. The major component of this architecture is a 2D cellular network composed of simple reprogrammable processors, enabling the Hessian Blob Detector and Haar Response Calculation, which are the most computing-intensive stage of the Speeded Up Robust Features (SURF) algorithm. Combining this 2D cellular network and dedicated hardware for SURF descriptors, this architecture achieves real-time image feature detection with minimal software in the host processor. A prototype FPGA implementation of the proposed architecture achieves 1318.9 GOPS general pixel processing @ 100 MHz clock and achieves up to 118 fps in VGA (640 × 480) image feature detection. The proposed architecture is stand-alone and scalable so it is easy to be migrated into VLSI implementation.

  8. Middleware in Modern High Performance Computing System Architectures

    SciTech Connect

    Engelmann, Christian; Ong, Hong Hoe; Scott, Stephen L

    2007-01-01

    A recent trend in modern high performance computing (HPC) system architectures employs ''lean'' compute nodes running a lightweight operating system (OS). Certain parts of the OS as well as other system software services are moved to service nodes in order to increase performance and scalability. This paper examines the impact of this HPC system architecture trend on HPC ''middleware'' software solutions, which traditionally equip HPC systems with advanced features, such as parallel and distributed programming models, appropriate system resource management mechanisms, remote application steering and user interaction techniques. Since the approach of keeping the compute node software stack small and simple is orthogonal to the middleware concept of adding missing OS features between OS and application, the role and architecture of middleware in modern HPC systems needs to be revisited. The result is a paradigm shift in HPC middleware design, where single middleware services are moved to service nodes, while runtime environments (RTEs) continue to reside on compute nodes.

  9. Architecture and applications of the HEP multiprocessor computer system

    SciTech Connect

    Smith, B.J.; Fink, D.J.

    1982-01-01

    The HEP computer system is a large scale scientific parallel computer employing shared resource MIMD architecture. The hardware and software facilities provided by the system are described, and techniques found to be useful in programming the system are also discussed. 3 references.

  10. Computer Architecture. (Latest Citations from the Aerospace Database)

    NASA Technical Reports Server (NTRS)

    1996-01-01

    The bibliography contains citations concerning research and development in the field of computer architecture. Design of computer systems, microcomputer components, and digital networks are among the topics discussed. Multimicroprocessor system performance, software development, and aerospace avionics applications are also included. (Contains 50-250 citations and includes a subject term index and title list.)

  11. The Contribution of Visualization to Learning Computer Architecture

    ERIC Educational Resources Information Center

    Yehezkel, Cecile; Ben-Ari, Mordechai; Dreyfus, Tommy

    2007-01-01

    This paper describes a visualization environment and associated learning activities designed to improve learning of computer architecture. The environment, EasyCPU, displays a model of the components of a computer and the dynamic processes involved in program execution. We present the results of a research program that analysed the contribution of…

  12. Braid group representation on quantum computation

    SciTech Connect

    Aziz, Ryan Kasyfil; Muchtadi-Alamsyah, Intan

    2015-09-30

    There are many studies about topological representation of quantum computation recently. One of diagram representation of quantum computation is by using ZX-Calculus. In this paper we will make a diagrammatical scheme of Dense Coding. We also proved that ZX-Calculus diagram of maximally entangle state satisfies Yang-Baxter Equation and therefore, we can construct a Braid Group representation of set of maximally entangle state.

  13. Delayed commutation in quantum computer networks.

    PubMed

    García-Escartín, Juan Carlos; Chamorro-Posada, Pedro

    2006-09-15

    In the same way that classical computer networks connect and enhance the capabilities of classical computers, quantum networks can combine the advantages of quantum information and communication. We propose a nonclassical network element, a delayed commutation switch, that can solve the problem of switching time in packet switching networks. With the help of some local ancillary qubits and superdense codes, we can route a qubit packet after part of it has left the network node. PMID:17025870

  14. Fault tolerant hypercube computer system architecture

    NASA Technical Reports Server (NTRS)

    Madan, Herb S. (Inventor); Chow, Edward (Inventor)

    1989-01-01

    A fault-tolerant multiprocessor computer system of the hypercube type comprising a hierarchy of computers of like kind which can be functionally substituted for one another as necessary is disclosed. Communication between the working nodes is via one communications network while communications between the working nodes and watch dog nodes and load balancing nodes higher in the structure is via another communications network separate from the first. A typical branch of the hierarchy reporting to a master node or host computer comprises, a plurality of first computing nodes; a first network of message conducting paths for interconnecting the first computing nodes as a hypercube. The first network provides a path for message transfer between the first computing nodes; a first watch dog node; and a second network of message connecting paths for connecting the first computing nodes to the first watch dog node independent from the first network, the second network provides an independent path for test message and reconfiguration affecting transfers between the first computing nodes and the first switch watch dog node. There is additionally, a plurality of second computing nodes; a third network of message conducting paths for interconnecting the second computing nodes as a hypercube. The third network provides a path for message transfer between the second computing nodes; a fourth network of message conducting paths for connecting the second computing nodes to the first watch dog node independent from the third network. The fourth network provides an independent path for test message and reconfiguration affecting transfers between the second computing nodes and the first watch dog node; and a first multiplexer disposed between the first watch dog node and the second and fourth networks for allowing the first watch dog node to selectively communicate with individual ones of the computing nodes through the second and fourth networks; as well as, a second watch dog node

  15. A memory-array architecture for computer vision

    SciTech Connect

    Balsara, P.T.

    1989-01-01

    With the fast advances in the area of computer vision and robotics there is a growing need for machines that can understand images at a very high speed. A conventional von Neumann computer is not suited for this purpose because it takes a tremendous amount of time to solve most typical image processing problems. Exploiting the inherent parallelism present in various vision tasks can significantly reduce the processing time. Fortunately, parallelism is increasingly affordable as hardware gets cheaper. Thus it is now imperative to study computer vision in a parallel processing framework. The author should first design a computational structure which is well suited for a wide range of vision tasks and then develop parallel algorithms which can run efficiently on this structure. Recent advances in VLSI technology have led to several proposals for parallel architectures for computer vision. In this thesis he demonstrates that a memory array architecture with efficient local and global communication capabilities can be used for high speed execution of a wide range of computer vision tasks. This architecture, called the Access Constrained Memory Array Architecture (ACMAA), is efficient for VLSI implementation because of its modular structure, simple interconnect and limited global control. Several parallel vision algorithms have been designed for this architecture. The choice of vision problems demonstrates the versatility of ACMAA for a wide range of vision tasks. These algorithms were simulated on a high level ACMAA simulator running on the Intel iPSC/2 hypercube, a parallel architecture. The results of this simulation are compared with those of sequential algorithms running on a single hypercube node. Details of the ACMAA processor architecture are also presented.

  16. Acausal measurement-based quantum computing

    NASA Astrophysics Data System (ADS)

    Morimae, Tomoyuki

    2014-07-01

    In measurement-based quantum computing, there is a natural "causal cone" among qubits of the resource state, since the measurement angle on a qubit has to depend on previous measurement results in order to correct the effect of by-product operators. If we respect the no-signaling principle, by-product operators cannot be avoided. Here we study the possibility of acausal measurement-based quantum computing by using the process matrix framework [Oreshkov, Costa, and Brukner, Nat. Commun. 3, 1092 (2012), 10.1038/ncomms2076]. We construct a resource process matrix for acausal measurement-based quantum computing restricting local operations to projective measurements. The resource process matrix is an analog of the resource state of the standard causal measurement-based quantum computing. We find that if we restrict local operations to projective measurements the resource process matrix is (up to a normalization factor and trivial ancilla qubits) equivalent to the decorated graph state created from the graph state of the corresponding causal measurement-based quantum computing. We also show that it is possible to consider a causal game whose causal inequality is violated by acausal measurement-based quantum computing.

  17. Architecture independent environment for developing engineering software on MIMD computers

    NASA Technical Reports Server (NTRS)

    Valimohamed, Karim A.; Lopez, L. A.

    1990-01-01

    Engineers are constantly faced with solving problems of increasing complexity and detail. Multiple Instruction stream Multiple Data stream (MIMD) computers have been developed to overcome the performance limitations of serial computers. The hardware architectures of MIMD computers vary considerably and are much more sophisticated than serial computers. Developing large scale software for a variety of MIMD computers is difficult and expensive. There is a need to provide tools that facilitate programming these machines. First, the issues that must be considered to develop those tools are examined. The two main areas of concern were architecture independence and data management. Architecture independent software facilitates software portability and improves the longevity and utility of the software product. It provides some form of insurance for the investment of time and effort that goes into developing the software. The management of data is a crucial aspect of solving large engineering problems. It must be considered in light of the new hardware organizations that are available. Second, the functional design and implementation of a software environment that facilitates developing architecture independent software for large engineering applications are described. The topics of discussion include: a description of the model that supports the development of architecture independent software; identifying and exploiting concurrency within the application program; data coherence; engineering data base and memory management.

  18. Thrifty: An Exascale Architecture for Energy Proportional Computing

    SciTech Connect

    Torrellas, Josep

    2014-12-23

    The objective of this project is to design key aspects of an exascale architecture called Thrifty that addresses the challenges of power/energy efficiency, resiliency, and performance in exascale systems. The project includes work on computer architecture (Josep Torrellas from University of Illinois), compilation (Daniel Quinlan from Lawrence Livermore National Laboratory), runtime and applications (Laura Carrington from University of California San Diego), and circuits (Wilfred Pinfold from Intel Corporation).

  19. Generating Efficient Quantum Chemistry Codes for Novel Architectures.

    PubMed

    Titov, Alexey V; Ufimtsev, Ivan S; Luehr, Nathan; Martinez, Todd J

    2013-01-01

    We describe an extension of our graphics processing unit (GPU) electronic structure program TeraChem to include atom-centered Gaussian basis sets with d angular momentum functions. This was made possible by a "meta-programming" strategy that leverages computer algebra systems for the derivation of equations and their transformation to correct code. We generate a multitude of code fragments that are formally mathematically equivalent, but differ in their memory and floating-point operation footprints. We then select between different code fragments using empirical testing to find the highest performing code variant. This leads to an optimal balance of floating-point operations and memory bandwidth for a given target architecture without laborious manual tuning. We show that this approach is capable of similar performance compared to our hand-tuned GPU kernels for basis sets with s and p angular momenta. We also demonstrate that mixed precision schemes (using both single and double precision) remain stable and accurate for molecules with d functions. We provide benchmarks of the execution time of entire self-consistent field (SCF) calculations using our GPU code and compare to mature CPU based codes, showing the benefits of the GPU architecture for electronic structure theory with appropriately redesigned algorithms. We suggest that the meta-programming and empirical performance optimization approach may be important in future computational chemistry applications, especially in the face of quickly evolving computer architectures. PMID:26589024

  20. Heavy Lift Vehicle (HLV) Avionics Flight Computing Architecture Study

    NASA Technical Reports Server (NTRS)

    Hodson, Robert F.; Chen, Yuan; Morgan, Dwayne R.; Butler, A. Marc; Sdhuh, Joseph M.; Petelle, Jennifer K.; Gwaltney, David A.; Coe, Lisa D.; Koelbl, Terry G.; Nguyen, Hai D.

    2011-01-01

    A NASA multi-Center study team was assembled from LaRC, MSFC, KSC, JSC and WFF to examine potential flight computing architectures for a Heavy Lift Vehicle (HLV) to better understand avionics drivers. The study examined Design Reference Missions (DRMs) and vehicle requirements that could impact the vehicles avionics. The study considered multiple self-checking and voting architectural variants and examined reliability, fault-tolerance, mass, power, and redundancy management impacts. Furthermore, a goal of the study was to develop the skills and tools needed to rapidly assess additional architectures should requirements or assumptions change.

  1. Waveguide-QED-Based Photonic Quantum Computation

    NASA Astrophysics Data System (ADS)

    Zheng, Huaixiu; Gauthier, Daniel J.; Baranger, Harold U.

    2013-08-01

    We propose a new scheme for quantum computation using flying qubits—propagating photons in a one-dimensional waveguide interacting with matter qubits. Photon-photon interactions are mediated by the coupling to a four-level system, based on which photon-photon π-phase gates (controlled-not) can be implemented for universal quantum computation. We show that high gate fidelity is possible, given recent dramatic experimental progress in superconducting circuits and photonic-crystal waveguides. The proposed system can be an important building block for future on-chip quantum networks.

  2. Hamiltonian quantum computer in one dimension

    NASA Astrophysics Data System (ADS)

    Wei, Tzu-Chieh; Liang, John C.

    2015-12-01

    Quantum computation can be achieved by preparing an appropriate initial product state of qudits and then letting it evolve under a fixed Hamiltonian. The readout is made by measurement on individual qudits at some later time. This approach is called the Hamiltonian quantum computation and it includes, for example, the continuous-time quantum cellular automata and the universal quantum walk. We consider one spatial dimension and study the compromise between the locality k and the local Hilbert space dimension d . For geometrically 2-local (i.e., k =2 ), it is known that d =8 is already sufficient for universal quantum computation but the Hamiltonian is not translationally invariant. As the locality k increases, it is expected that the minimum required d should decrease. We provide a construction of a Hamiltonian quantum computer for k =3 with d =5 . One implication is that simulating one-dimensional chains of spin-2 particles is BQP-complete (BQP denotes "bounded error, quantum polynomial time"). Imposing translation invariance will increase the required d . For this we also construct another 3-local (k =3 ) Hamiltonian that is invariant under translation of a unit cell of two sites but that requires d to be 8.

  3. Aerodynamic optimization studies on advanced architecture computers

    NASA Technical Reports Server (NTRS)

    Chawla, Kalpana

    1995-01-01

    The approach to carrying out multi-discipline aerospace design studies in the future, especially in massively parallel computing environments, comprises of choosing (1) suitable solvers to compute solutions to equations characterizing a discipline, and (2) efficient optimization methods. In addition, for aerodynamic optimization problems, (3) smart methodologies must be selected to modify the surface shape. In this research effort, a 'direct' optimization method is implemented on the Cray C-90 to improve aerodynamic design. It is coupled with an existing implicit Navier-Stokes solver, OVERFLOW, to compute flow solutions. The optimization method is chosen such that it can accomodate multi-discipline optimization in future computations. In the work , however, only single discipline aerodynamic optimization will be included.

  4. Simulating physical phenomena with a quantum computer

    NASA Astrophysics Data System (ADS)

    Ortiz, Gerardo

    2003-03-01

    In a keynote speech at MIT in 1981 Richard Feynman raised some provocative questions in connection to the exact simulation of physical systems using a special device named a ``quantum computer'' (QC). At the time it was known that deterministic simulations of quantum phenomena in classical computers required a number of resources that scaled exponentially with the number of degrees of freedom, and also that the probabilistic simulation of certain quantum problems were limited by the so-called sign or phase problem, a problem believed to be of exponential complexity. Such a QC was intended to mimick physical processes exactly the same as Nature. Certainly, remarks coming from such an influential figure generated widespread interest in these ideas, and today after 21 years there are still some open questions. What kind of physical phenomena can be simulated with a QC?, How?, and What are its limitations? Addressing and attempting to answer these questions is what this talk is about. Definitively, the goal of physics simulation using controllable quantum systems (``physics imitation'') is to exploit quantum laws to advantage, and thus accomplish efficient imitation. Fundamental is the connection between a quantum computational model and a physical system by transformations of operator algebras. This concept is a necessary one because in Quantum Mechanics each physical system is naturally associated with a language of operators and thus can be considered as a possible model of quantum computation. The remarkable result is that an arbitrary physical system is naturally simulatable by another physical system (or QC) whenever a ``dictionary'' between the two operator algebras exists. I will explain these concepts and address some of Feynman's concerns regarding the simulation of fermionic systems. Finally, I will illustrate the main ideas by imitating simple physical phenomena borrowed from condensed matter physics using quantum algorithms, and present experimental

  5. CALL FOR PAPERS: Optical implementation of quantum computers

    NASA Astrophysics Data System (ADS)

    Rarity, John; Weinfurter, Harald

    2004-09-01

    A topical issue of Journal of Optics B: Quantum and Semiclassical Optics will be devoted to recent advances in optical implementation of quantum computers. The topics to be covered will include, but are not limited to: bullet Linear optics quantum gates bullet Progress towards nonlinear optics quantum gates bullet Interface between optical qubits and atomic/solid state qubits bullet Novel architectures bullet Single-photon sources and detectors bullet Photonic quantum networks bullet Few-qubit applications The DEADLINE for submission of contributions is 15 January 2005 to allow the topical issue to be published in about October 2005. All contributions will be peer-reviewed in accordance with the normal refereeing procedures and standards of Journal of Optics B: Quantum and Semiclassical Optics. Submissions should preferably be in either standard LaTeX form or Microsoft Word. Advice on publishing your work in the journal may be found at www.iop.org/journals/authors/jopb. There are no page charges for publication. The corresponding author of each paper published will receive a complimentary copy of the topical issue. Contributions to the topical issue should preferably be submitted electronically at www.iop.org/journals/authors/jopb or by e-mail to jopb@iop.org. Authors unable to submit online or by e-mail may send hard copy contributions (enclosing the electronic code) to: Dr Claire Bedrock (Publisher), Journal of Optics B: Quantum and Semiclassical Optics, Institute of Physics Publishing, Dirac House, Temple Back, Bristol BS1 6BE, UK. All contributions should be accompanied by a readme file or covering letter, quoting `JOPB Topical Issue - Optical implementation of quantum computers', giving the postal and e-mail addresses for correspondence. Any subsequent change of address should be notified to the publishing office. We look forward to receiving your contribution to this topical issue.

  6. Prospects for quantum computing: Extremely doubtful

    NASA Astrophysics Data System (ADS)

    Dyakonov, M. I.

    2014-09-01

    The quantum computer is supposed to process information by applying unitary transformations to 2N complex amplitudes defining the state of N qubits. A useful machine needing N 103 or more, the number of continuous parameters describing the state of a quantum computer at any given moment is at least 21000 10300 which is much greater than the number of protons in the Universe. However, the theorists believe that the feasibility of large-scale quantum computing has been proved via the “threshold theorem”. Like for any theorem, the proof is based on a number of assumptions considered as axioms. However, in the physical world none of these assumptions can be fulfilled exactly. Any assumption can be only approached with some limited precision. So, the rather meaningless “error per qubit per gate” threshold must be supplemented by a list of the precisions with which all assumptions behind the threshold theorem should hold. Such a list still does not exist. The theory also seems to ignore the undesired free evolution of the quantum computer caused by the energy differences of quantum states entering any given superposition. Another important point is that the hypothetical quantum computer will be a system of 103 -106 qubits PLUS an extremely complex and monstrously sophisticated classical apparatus. This huge and strongly nonlinear system will generally exhibit instabilities and chaotic behavior.

  7. Irreconcilable difference between quantum walks and adiabatic quantum computing

    NASA Astrophysics Data System (ADS)

    Wong, Thomas G.; Meyer, David A.

    2016-06-01

    Continuous-time quantum walks and adiabatic quantum evolution are two general techniques for quantum computing, both of which are described by Hamiltonians that govern their evolutions by Schrödinger's equation. In the former, the Hamiltonian is fixed, while in the latter, the Hamiltonian varies with time. As a result, their formulations of Grover's algorithm evolve differently through Hilbert space. We show that this difference is fundamental; they cannot be made to evolve along each other's path without introducing structure more powerful than the standard oracle for unstructured search. For an adiabatic quantum evolution to evolve like the quantum walk search algorithm, it must interpolate between three fixed Hamiltonians, one of which is complex and introduces structure that is stronger than the oracle for unstructured search. Conversely, for a quantum walk to evolve along the path of the adiabatic search algorithm, it must be a chiral quantum walk on a weighted, directed star graph with structure that is also stronger than the oracle for unstructured search. Thus, the two techniques, although similar in being described by Hamiltonians that govern their evolution, compute by fundamentally irreconcilable means.

  8. LINCS: Livermore's network architecture. [Octopus computing network

    SciTech Connect

    Fletcher, J.G.

    1982-01-01

    Octopus, a local computing network that has been evolving at the Lawrence Livermore National Laboratory for over fifteen years, is currently undergoing a major revision. The primary purpose of the revision is to consolidate and redefine the variety of conventions and formats, which have grown up over the years, into a single standard family of protocols, the Livermore Interactive Network Communication Standard (LINCS). This standard treats the entire network as a single distributed operating system such that access to a computing resource is obtained in a single way, whether that resource is local (on the same computer as the accessing process) or remote (on another computer). LINCS encompasses not only communication but also such issues as the relationship of customer to server processes and the structure, naming, and protection of resources. The discussion includes: an overview of the Livermore user community and computing hardware, the functions and structure of each of the seven layers of LINCS protocol, the reasons why we have designed our own protocols and why we are dissatisfied by the directions that current protocol standards are taking.

  9. Quantum Computing in Silicon with Donor Electron Spins

    NASA Astrophysics Data System (ADS)

    Simmons, Michelle

    2014-03-01

    Extremely long electron and nuclear spin coherence times have recently been demonstrated in isotopically pure Si-28 making silicon one of the most promising semiconductor materials for spin based quantum information. The two level spin state of single electrons bound to shallow phosphorus donors in silicon in particular provide well defined, reproducible qubits and represent a promising system for a scalable quantum computer in silicon. An important challenge in these systems is the realisation of an architecture, where we can position donors within a crystalline environment with approx. 20-50nm separation, individually address each donor, manipulate the electron spins using ESR techniques and read-out their spin states. We have developed a unique fabrication strategy for a scalable quantum computer in silicon using scanning tunneling microscope hydrogen lithography to precisely position individual P donors in a Si crystal aligned with nanoscale precision to local control gates necessary to initialize, manipulate, and read-out the spin states. During this talk I will focus on demonstrating electronic transport characteristics and single-shot spin read-out of precisely-positioned P donors in Si. Additionally I will report on our recent progress in performing single spin rotations by locally applying oscillating magnetic fields and initial characterization of transport devices with two and three single donors. The challenges of scaling up to practical 2D architectures will also be discussed.

  10. Classical versus quantum errors in quantum computation of dynamical systems.

    PubMed

    Rossini, Davide; Benenti, Giuliano; Casati, Giulio

    2004-11-01

    We analyze the stability of a quantum algorithm simulating the quantum dynamics of a system with different regimes, ranging from global chaos to integrability. We compare, in these different regimes, the behavior of the fidelity of quantum motion when the system's parameters are perturbed or when there are unitary errors in the quantum gates implementing the quantum algorithm. While the first kind of errors has a classical limit, the second one has no classical analog. It is shown that, whereas in the first case ("classical errors") the decay of fidelity is very sensitive to the dynamical regime, in the second case ("quantum errors") it is almost independent of the dynamical behavior of the simulated system. Therefore, the rich variety of behaviors found in the study of the stability of quantum motion under "classical" perturbations has no correspondence in the fidelity of quantum computation under its natural perturbations. In particular, in this latter case it is not possible to recover the semiclassical regime in which the fidelity decays with a rate given by the classical Lyapunov exponent. PMID:15600737

  11. Computational architecture for integrated controls and structures design

    NASA Technical Reports Server (NTRS)

    Belvin, W. Keith; Park, K. C.

    1989-01-01

    To facilitate the development of control structure interaction (CSI) design methodology, a computational architecture for interdisciplinary design of active structures is presented. The emphasis of the computational procedure is to exploit existing sparse matrix structural analysis techniques, in-core data transfer with control synthesis programs, and versatility in the optimization methodology to avoid unnecessary structural or control calculations. The architecture is designed such that all required structure, control and optimization analyses are performed within one program. Hence, the optimization strategy is not unduly constrained by cold starts of existing structural analysis and control synthesis packages.

  12. Panel on future directions in parallel computer architecture

    SciTech Connect

    VanTilborg, A.M. )

    1989-06-01

    One of the program highlights of the 15th Annual International Symposium on Computer Architecture, held May 30 - June 2, 1988 in Honolulu, was a panel session on future directions in parallel computer architecture. The panel was organized and chaired by the author, and was comprised of Prof. Jack Dennis (NASA Ames Research Institute for Advanced Computer Science), Prof. H.T. Kung (Carnegie Mellon), and Dr. Burton Smith (Tera Computer Company). The objective of the panel was to identify the likely trajectory of future parallel computer system progress, particularly from the sandpoint of marketplace acceptance. Approximately 250 attendees participated in the session, in which each panelist began with a ten minute viewgraph explanation of his views, followed by an open and sometimes lively exchange with the audience and fellow panelists. The session ran for ninety minutes.

  13. Qubus ancilla-driven quantum computation

    SciTech Connect

    Brown, Katherine Louise; De, Suvabrata; Kendon, Viv; Munro, Bill

    2014-12-04

    Hybrid matter-optical systems offer a robust, scalable path to quantum computation. Such systems have an ancilla which acts as a bus connecting the qubits. We demonstrate how using a continuous variable qubus as the ancilla provides savings in the total number of operations required when computing with many qubits.

  14. Architecture and grid application of cluster computing system

    NASA Astrophysics Data System (ADS)

    Lv, Yi; Yu, Shuiqin; Mao, Youju

    2004-11-01

    Recently, people pay more attention to the grid technology. It can not only connect all kinds of resources in the network, but also put them into a super transparent computing environment for customers to realize mete-computing which can share computing resources. Traditional parallel computing system, such as SMP(Symmetrical multiprocessor) and MPP(massively parallel processor), use multi-processors to raise computing speed in a close coupling way, so the flexible and scalable performance of the system are limited, as a result of it, the system can't meet the requirement of the grid technology. In this paper, the architecture of cluster computing system applied in grid nodes is introduced. It mainly includes the following aspects. First, the network architecture of cluster computing system in grid nodes is analyzed and designed. Second, how to realize distributing computing (including coordinating computing and sharing computing) of cluster computing system in grid nodes to construct virtual node computers is discussed. Last, communication among grid nodes is analyzed. In other words, it discusses how to realize single reflection to let all the service requirements from customers be met through sending to the grid nodes.

  15. Neuromorphic Computing – From Materials Research to Systems Architecture Roundtable

    SciTech Connect

    Schuller, Ivan K.; Stevens, Rick; Pino, Robinson; Pechan, Michael

    2015-10-29

    Computation in its many forms is the engine that fuels our modern civilization. Modern computation—based on the von Neumann architecture—has allowed, until now, the development of continuous improvements, as predicted by Moore’s law. However, computation using current architectures and materials will inevitably—within the next 10 years—reach a limit because of fundamental scientific reasons. DOE convened a roundtable of experts in neuromorphic computing systems, materials science, and computer science in Washington on October 29-30, 2015 to address the following basic questions: Can brain-like (“neuromorphic”) computing devices based on new material concepts and systems be developed to dramatically outperform conventional CMOS based technology? If so, what are the basic research challenges for materials sicence and computing? The overarching answer that emerged was: The development of novel functional materials and devices incorporated into unique architectures will allow a revolutionary technological leap toward the implementation of a fully “neuromorphic” computer. To address this challenge, the following issues were considered: The main differences between neuromorphic and conventional computing as related to: signaling models, timing/clock, non-volatile memory, architecture, fault tolerance, integrated memory and compute, noise tolerance, analog vs. digital, and in situ learning New neuromorphic architectures needed to: produce lower energy consumption, potential novel nanostructured materials, and enhanced computation Device and materials properties needed to implement functions such as: hysteresis, stability, and fault tolerance Comparisons of different implementations: spin torque, memristors, resistive switching, phase change, and optical schemes for enhanced breakthroughs in performance, cost, fault tolerance, and/or manufacturability.

  16. Biologically inspired path to quantum computer

    NASA Astrophysics Data System (ADS)

    Ogryzko, Vasily; Ozhigov, Yuri

    2014-12-01

    We describe an approach to quantum computer inspired by the information processing at the molecular level in living cells. It is based on the separation of a small ensemble of qubits inside the living system (e.g., a bacterial cell), such that coherent quantum states of this ensemble remain practically unchanged for a long time. We use the notion of a quantum kernel to describe such an ensemble. Quantum kernel is not strictly connected with certain particles; it permanently exchanges atoms and molecules with the environment, which makes quantum kernel a virtual notion. There are many reasons to expect that the state of quantum kernel of a living system can be treated as the stationary state of some Hamiltonian. While the quantum kernel is responsible for the stability of dynamics at the time scale of cellular life, at the longer inter-generation time scale it can change, varying smoothly in the course of biological evolution. To the first level of approximation, quantum kernel can be described in the framework of qubit modification of Jaynes-Cummings-Hubbard model, in which the relaxation corresponds to the exchange of matter between quantum kernel and the rest of the cell and is represented as Lindblad super-operators.

  17. Effective pure states for bulk quantum computation

    SciTech Connect

    Knill, E.; Chuang, I.; Laflamme, R.

    1998-05-01

    In bulk quantum computation one can manipulate a large number of indistinguishable quantum computers by parallel unitary operations and measure expectation values of certain observables with limited sensitivity. The initial state of each computer in the ensemble is known but not pure. Methods for obtaining effective pure input states by a series of manipulations have been described by Gershenfeld and Chuang (logical labeling) [Science {bold 275}, 350 (1997)] and Cory {ital et al.} (spatial averaging) [Proc. Natl. Acad. Sci. USA {bold 94}, 1634 (1997)] for the case of quantum computation with nuclear magnetic resonance. We give a different technique called temporal averaging. This method is based on classical randomization, requires no ancilla quantum bits, and can be implemented in nuclear magnetic resonance without using gradient fields. We introduce several temporal averaging algorithms suitable for both high-temperature and low-temperature bulk quantum computing and analyze the signal-to-noise behavior of each. Most of these algorithms require only a constant multiple of the number of experiments needed by the other methods for creating effective pure states. {copyright} {ital 1998} {ital The American Physical Society}

  18. Quantum computations: algorithms and error correction

    NASA Astrophysics Data System (ADS)

    Kitaev, A. Yu

    1997-12-01

    Contents §0. Introduction §1. Abelian problem on the stabilizer §2. Classical models of computations2.1. Boolean schemes and sequences of operations2.2. Reversible computations §3. Quantum formalism3.1. Basic notions and notation3.2. Transformations of mixed states3.3. Accuracy §4. Quantum models of computations4.1. Definitions and basic properties4.2. Construction of various operators from the elements of a basis4.3. Generalized quantum control and universal schemes §5. Measurement operators §6. Polynomial quantum algorithm for the stabilizer problem §7. Computations with perturbations: the choice of a model §8. Quantum codes (definitions and general properties)8.1. Basic notions and ideas8.2. One-to-one codes8.3. Many-to-one codes §9. Symplectic (additive) codes9.1. Algebraic preparation9.2. The basic construction9.3. Error correction procedure9.4. Torus codes §10. Error correction in the computation process: general principles10.1. Definitions and results10.2. Proofs §11. Error correction: concrete procedures11.1. The symplecto-classical case11.2. The case of a complete basis Bibliography

  19. Power of one qumode for quantum computation

    NASA Astrophysics Data System (ADS)

    Liu, Nana; Thompson, Jayne; Weedbrook, Christian; Lloyd, Seth; Vedral, Vlatko; Gu, Mile; Modi, Kavan

    2016-05-01

    Although quantum computers are capable of solving problems like factoring exponentially faster than the best-known classical algorithms, determining the resources responsible for their computational power remains unclear. An important class of problems where quantum computers possess an advantage is phase estimation, which includes applications like factoring. We introduce a computational model based on a single squeezed state resource that can perform phase estimation, which we call the power of one qumode. This model is inspired by an interesting computational model known as deterministic quantum computing with one quantum bit (DQC1). Using the power of one qumode, we identify that the amount of squeezing is sufficient to quantify the resource requirements of different computational problems based on phase estimation. In particular, we can use the amount of squeezing to quantitatively relate the resource requirements of DQC1 and factoring. Furthermore, we can connect the squeezing to other known resources like precision, energy, qudit dimensionality, and qubit number. We show the circumstances under which they can likewise be considered good resources.

  20. Universal quantum computation with unlabelled qubits

    NASA Astrophysics Data System (ADS)

    Severini, Simone

    2006-06-01

    We show that an nth root of the Walsh-Hadamard transform (obtained from the Hadamard gate and a cyclic permutation of the qubits), together with two diagonal matrices, namely a local qubit-flip (for a fixed but arbitrary qubit) and a non-local phase-flip (for a fixed but arbitrary coefficient), can do universal quantum computation on n qubits. A quantum computation, making use of n qubits and based on these operations, is then a word of variable length, but whose letters are always taken from an alphabet of cardinality three. Therefore, in contrast with other universal sets, no choice of qubit lines is needed for the application of the operations described here. A quantum algorithm based on this set can be interpreted as a discrete diffusion of a quantum particle on a de Bruijn graph, corrected on-the-fly by auxiliary modifications of the phases associated with the arcs.

  1. Accelerating commutation circuits in quantum computer networks

    NASA Astrophysics Data System (ADS)

    Jiang, Min; Huang, Xu; Chen, Xiaoping; Zhang, Zeng-ke

    2012-12-01

    In a high speed and packet-switched quantum computer network, a packet routing delay often leads to traffic jams, becoming a severe bottleneck for speeding up the transmission rate. Based on the delayed commutation circuit proposed in Phys. Rev. Lett. 97, 110502 (2006), we present an improved scheme for accelerating network transmission. For two more realistic scenarios, we utilize the characteristic of a quantum state to simultaneously implement a data switch and transmission that makes it possible to reduce the packet delay and route a qubit packet even before its address is determined. This circuit is further extended to the quantum network for the transmission of the unknown quantum information. The analysis demonstrates that quantum communication technology can considerably reduce the processing delay time and build faster and more efficient packet-switched networks.

  2. Quantum learning in a quantum lattice gas computer

    NASA Astrophysics Data System (ADS)

    Behrman, Elizabeth; Steck, James

    2015-04-01

    Quantum lattice gas is the logical generalization of quantum cellular automata. At low energy the dynamics are well described by the Gross-Pitaevskii equation in the mean field limit, which is an effective nonlinear interaction model of a Bose-Einstein condensate. In previous work, we have shown in simulation that both spatial and temporal models of quantum learning computers can be used to ``design'' non-trivial quantum algorithms. The advantages of quantum learning over the usual practice of using quantum gate building blocks are, first, the rapidity with which the problem can be solved, without having to decompose the problem; second, the fact that our technique can be used readily even when the problem, or the operator, is not well understood; and, third, that because the interactions are a natural part of the physical system, connectivity is automatic. The advantage to quantum learning obviously grows with the size and the complexity of the problem. We develop and present our learning algorithm as applied to the mean field lattice gas equation, and present a few preliminary results.

  3. Quantum learning for a quantum lattice gas computer

    NASA Astrophysics Data System (ADS)

    Behrman, Elizabeth; Steck, James

    2015-03-01

    Quantum lattice gas is the logical generalization of quantum cellular automata. In low energy the dynamics are well described by the Gross-Pitaevskii equation in the mean field limit, which is an effective nonlinear interaction model of a Bose-Einstein condensate. In previous work, we have shown in simulation that both spatial and temporal models of quantum learning computers can be used to ``design'' non-trivial quantum algorithms. The advantages of quantum learning over the usual practice of using quantum gate building blocks are, first, the rapidity with which the problem can be solved, without having to decompose the problem; second, the fact that our technique can be used readily even when the problem, or the operator, is not well understood; and, third, that because the interactions are a natural part of the physical system, connectivity is automatic. The advantage to quantum learning obviously grows with the size and the complexity of the problem. We develop and present our learning algorithm as applied to the mean field lattice gas equation, and present a few preliminary results.

  4. Entanglement and Quantum Computation: An Overview

    SciTech Connect

    Perez, R.B.

    2000-06-27

    This report presents a selective compilation of basic facts from the fields of particle entanglement and quantum information processing prepared for those non-experts in these fields that may have interest in an area of physics showing counterintuitive, ''spooky'' (Einstein's words) behavior. In fact, quantum information processing could, in the near future, provide a new technology to sustain the benefits to the U.S. economy due to advanced computer technology.

  5. Computations in quantum mechanics made easy

    NASA Astrophysics Data System (ADS)

    Korsch, H. J.; Rapedius, K.

    2016-09-01

    Convenient and simple numerical techniques for performing quantum computations based on matrix representations of Hilbert space operators are presented and illustrated by various examples. The applications include the calculations of spectral and dynamical properties for one-dimensional and two-dimensional single-particle systems as well as bosonic many-particle and open quantum systems. Due to their technical simplicity these methods are well suited as a tool for teaching quantum mechanics to undergraduates and graduates. Explicit implementations of the presented numerical methods in Matlab are given.

  6. Information-theoretic temporal Bell inequality and quantum computation

    SciTech Connect

    Morikoshi, Fumiaki

    2006-05-15

    An information-theoretic temporal Bell inequality is formulated to contrast classical and quantum computations. Any classical algorithm satisfies the inequality, while quantum ones can violate it. Therefore, the violation of the inequality is an immediate consequence of the quantumness in the computation. Furthermore, this approach suggests a notion of temporal nonlocality in quantum computation.

  7. Pipelined CPU Design with FPGA in Teaching Computer Architecture

    ERIC Educational Resources Information Center

    Lee, Jong Hyuk; Lee, Seung Eun; Yu, Heon Chang; Suh, Taeweon

    2012-01-01

    This paper presents a pipelined CPU design project with a field programmable gate array (FPGA) system in a computer architecture course. The class project is a five-stage pipelined 32-bit MIPS design with experiments on the Altera DE2 board. For proper scheduling, milestones were set every one or two weeks to help students complete the project on…

  8. In-Memory Computing Architectures for Sparse Distributed Memory.

    PubMed

    Kang, Mingu; Shanbhag, Naresh R

    2016-08-01

    This paper presents an energy-efficient and high-throughput architecture for Sparse Distributed Memory (SDM)-a computational model of the human brain [1]. The proposed SDM architecture is based on the recently proposed in-memory computing kernel for machine learning applications called Compute Memory (CM) [2], [3]. CM achieves energy and throughput efficiencies by deeply embedding computation into the memory array. SDM-specific techniques such as hierarchical binary decision (HBD) are employed to reduce the delay and energy further. The CM-based SDM (CM-SDM) is a mixed-signal circuit, and hence circuit-aware behavioral, energy, and delay models in a 65 nm CMOS process are developed in order to predict system performance of SDM architectures in the auto- and hetero-associative modes. The delay and energy models indicate that CM-SDM, in general, can achieve up to 25 × and 12 × delay and energy reduction, respectively, over conventional SDM. When classifying 16 × 16 binary images with high noise levels (input bad pixel ratios: 15%-25%) into nine classes, all SDM architectures are able to generate output bad pixel ratios (Bo) ≤ 2%. The CM-SDM exhibits negligible loss in accuracy, i.e., its Bo degradation is within 0.4% as compared to that of the conventional SDM. PMID:27305686

  9. Phonon-based scalable quantum computing and sensing (Presentation Video)

    NASA Astrophysics Data System (ADS)

    El-Kady, Ihab

    2015-04-01

    Quantum computing fundamentally depends on the ability to concurrently entangle and individually address/control a large number of qubits. In general, the primary inhibitors of large scale entanglement are qubit dependent; for example inhomogeneity in quantum dots, spectral crowding brought about by proximity-based entanglement in ions, weak interactions of neutral atoms, and the fabrication tolerances in the case of Si-vacancies or SQUIDs. We propose an inherently scalable solid-state qubit system with individually addressable qubits based on the coupling of a phonon with an acceptor impurity in a high-Q Phononic Crystal resonant cavity. Due to their unique nonlinear properties, phonons enable new opportunities for quantum devices and physics. We present a phononic crystal-based platform for observing the phonon analogy of cavity quantum electrodynamics, called phonodynamics, in a solid-state system. Practical schemes involve selective placement of a single acceptor atom in the peak of the strain field in a high-Q phononic crystal cavity that enables strong coupling of the phonon modes to the energy levels of the atom. A qubit is then created by entangling a phonon at the resonance frequency of the cavity with the atomic acceptor states. We show theoretical optimization of the cavity design and excitation waveguides, along with estimated performance figures of the phoniton system. Qubits based on this half-sound, half-matter quasi-particle, may outcompete other quantum architectures in terms of combined emission rate, coherence lifetime, and fabrication demands.

  10. Trading Classical and Quantum Computational Resources

    NASA Astrophysics Data System (ADS)

    Bravyi, Sergey; Smith, Graeme; Smolin, John A.

    2016-04-01

    We propose examples of a hybrid quantum-classical simulation where a classical computer assisted by a small quantum processor can efficiently simulate a larger quantum system. First, we consider sparse quantum circuits such that each qubit participates in O (1 ) two-qubit gates. It is shown that any sparse circuit on n +k qubits can be simulated by sparse circuits on n qubits and a classical processing that takes time 2O (k )poly (n ) . Second, we study Pauli-based computation (PBC), where allowed operations are nondestructive eigenvalue measurements of n -qubit Pauli operators. The computation begins by initializing each qubit in the so-called magic state. This model is known to be equivalent to the universal quantum computer. We show that any PBC on n +k qubits can be simulated by PBCs on n qubits and a classical processing that takes time 2O (k )poly (n ). Finally, we propose a purely classical algorithm that can simulate a PBC on n qubits in a time 2α npoly (n ) , where α ≈0.94 . This improves upon the brute-force simulation method, which takes time 2npoly (n ). Our algorithm exploits the fact that n -fold tensor products of magic states admit a low-rank decomposition into n -qubit stabilizer states.