Science.gov

Sample records for quantum computing technology

  1. Some Notes on Quantum Information Theory and Emerging Computing Technologies

    E-print Network

    Alexander Yu. Vlasov

    2015-03-24

    It is considered an interdependence of the theory of quantum computing and some perspective information technologies. A couple of illustrative and useful examples are discussed. The reversible computing from very beginning had the serious impact on the design of quantum computers and it is revisited first. Some applications of ternary circuits are also quite instructive and it may be useful in the quantum information theory.

  2. Scalable trap technology for quantum computing with ions

    E-print Network

    Eltony, Amira M. (Amira Madeleine)

    2015-01-01

    Quantum computers employ quantum mechanical effects, such as superposition and entanglement, to process information in a distinctive way, with advantages for simulation and for new, and in some cases more-efficient algorithms. ...

  3. Quantum Computation Quantum Information

    E-print Network

    Lomonaco Jr., Samuel J.

    Quantum Computation and Quantum Information Samuel J. Lomonaco, Jr. and Howard E. Brandt editors pages Havel, Timothy F., and Chris J. L. Doran Quantum Computing and the Jones Polynomial. Hadi Madjid Quantum Computation by Geometrical Means .................................... 6 pages

  4. Quantum Computing Computer Scientists

    E-print Network

    Yanofsky, Noson S.

    Quantum Computing for Computer Scientists Noson S. Yanofsky and Mirco A. Mannucci #12;© May 2007 Noson S. Yanofsky Mirco A. Mannucci #12;Quantum Computing for Computer Scientists Noson S. Yanofsky.3 Towards Higher-Level Quantum Programming 7.4 Quantum Computation Before Quantum Computers 8 Theoretical

  5. Quantum Computation

    E-print Network

    Dorit Aharonov

    1998-12-15

    In the last few years, theoretical study of quantum systems serving as computational devices has achieved tremendous progress. We now have strong theoretical evidence that quantum computers, if built, might be used as a dramatically powerful computational tool. This review is about to tell the story of theoretical quantum computation. I left out the developing topic of experimental realizations of the model, and neglected other closely related topics which are quantum information and quantum communication. As a result of narrowing the scope of this paper, I hope it has gained the benefit of being an almost self contained introduction to the exciting field of quantum computation. The review begins with background on theoretical computer science, Turing machines and Boolean circuits. In light of these models, I define quantum computers, and discuss the issue of universal quantum gates. Quantum algorithms, including Shor's factorization algorithm and Grover's algorithm for searching databases, are explained. I will devote much attention to understanding what the origins of the quantum computational power are, and what the limits of this power are. Finally, I describe the recent theoretical results which show that quantum computers maintain their complexity power even in the presence of noise, inaccuracies and finite precision. I tried to put all results in their context, asking what the implications to other issues in computer science and physics are. In the end of this review I make these connections explicit, discussing the possible implications of quantum computation on fundamental physical questions, such as the transition from quantum to classical physics.

  6. QuantumQuantum Computing ?Computing ?

    E-print Network

    Lomonaco Jr., Samuel J.

    Quantum Algorithms & Beyond ·· Distributive Quantum ComputingDistributive Quantum Computing ·· Topological quantumSci. & Electrical Engineering. & Electrical Engineering University of Maryland Baltimore County systemscrypto systems ·· More accurate weather simulation andMore accurate weather simulation

  7. Quantum technology for aerospace applications

    NASA Astrophysics Data System (ADS)

    Jia, Bin; Pham, Khanh; Chen, Genshe; Shen, Dan; Wang, Zhonghai; Wang, Gang; Blasch, Erik

    2014-06-01

    In this paper, quantum technology is introduced with three key topics, including quantum computing, quantum communication, and quantum devices. Using these dimensions of quantum techniques we briefly introduce their contributions to aerospace applications. The paper will help readers to understand the basic concepts of the quantum technology and their potential applications in space, air, and ground applications such as highly accurate target positioning.

  8. 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.

  9. Quantum computing and quantum information

    E-print Network

    Kais, Sabre

    Quantum computing and quantum information KAIS GROUP #12;Main themes Quantum algorithms applications of quantum computing: - Hidden abelian subgroup problem (Shor's alg., exponential speedup of qubits to surpass classical computation arXiv:quant-ph/0205095e.g. quantum chemistry: exact

  10. Unconventional Quantum Computing Devices

    E-print Network

    Seth Lloyd

    2000-03-31

    This paper investigates a variety of unconventional quantum computation devices, including fermionic quantum computers and computers that exploit nonlinear quantum mechanics. It is shown that unconventional quantum computing devices can in principle compute some quantities more rapidly than `conventional' quantum computers.

  11. 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.

  12. Quantum Computing, Metrology, and Imaging

    E-print Network

    Hwang Lee; Pavel Lougovski; Jonathan P. Dowling

    2005-06-17

    Information science is entering into a new era in which certain subtleties of quantum mechanics enables large enhancements in computational efficiency and communication security. Naturally, precise control of quantum systems required for the implementation of quantum information processing protocols implies potential breakthoughs in other sciences and technologies. We discuss recent developments in quantum control in optical systems and their applications in metrology and imaging.

  13. 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.

  14. 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.

  15. Quantum Computational Complexity

    E-print Network

    John Watrous

    2008-04-21

    This article surveys quantum computational complexity, with a focus on three fundamental notions: polynomial-time quantum computations, the efficient verification of quantum proofs, and quantum interactive proof systems. Properties of quantum complexity classes based on these notions, such as BQP, QMA, and QIP, are presented. Other topics in quantum complexity, including quantum advice, space-bounded quantum computation, and bounded-depth quantum circuits, are also discussed.

  16. Quantum Computation Zoya Gavrilov

    E-print Network

    Oliva, Aude

    Quantum Computation Zoya Gavrilov June 26, 2012 1 Introduction Quantum computation harnesses the power of nature by relying on the properties of quantum systems to both speed up classical computations, as well as to solve problems that are not classically computable. In essence, quantum computation makes

  17. Photonic quantum technologies

    NASA Astrophysics Data System (ADS)

    O'Brien, Jeremy

    2013-03-01

    Of the approaches to quantum computing, photons are appealing for their low-noise properties and ease of manipulation, and relevance to other quantum technologies, including communication, metrology and measurement. We report an integrated waveguide approach to photonic quantum circuits for high performance, miniaturization and scalability [6-10]. We address the challenges of scaling up quantum circuits using new insights into how controlled operations can be efficiently realised, demonstrating Shor's algorithm with consecutive CNOT gates and the iterative phase estimation algorithm. We have shown how quantum circuits can be reconfigured, using thermo-optic phase shifters to realise a highly reconfigurable quantum circuit, and electro-optic phase shifters in lithium niobate to rapidly manipulate the path and polarisation of telecomm wavelength single photons. We have addressed miniaturisation using multimode interference architectures to directly implement NxN Hadamard operations, and by using high refractive index contrast materials such as SiOxNy, in which we have implemented quantum walks of correlated photons, and Si, in which we have demonstrated generation of orbital angular momentum states of light. We have incorporated microfluidic channels for the delivery of samples to measure the concentration of a blood protein with entangled states of light. We have begun to address the integration of superconducting single photon detectors and diamond and non-linear single photon sources. Finally, we give an overview of recent work on fundamental aspects of quantum measurement, including a quantum version of Wheeler's delayed choice experiment.

  18. Hybrid quantum computing

    E-print Network

    Seth Lloyd

    2000-08-11

    Necessary and sufficient conditions are given for the construction of a hybrid quantum computer that operates on both continuous and discrete quantum variables. Such hybrid computers are shown to be more efficient than conventional quantum computers for performing a variety of quantum algorithms, such as computing eigenvectors and eigenvalues.

  19. Photonic quantum technologies (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    O'Brien, Jeremy L.

    2015-09-01

    The impact of quantum technology will be profound and far-reaching: secure communication networks for consumers, corporations and government; precision sensors for biomedical technology and environmental monitoring; quantum simulators for the design of new materials, pharmaceuticals and clean energy devices; and ultra-powerful quantum computers for addressing otherwise impossibly large datasets for machine learning and artificial intelligence applications. However, engineering quantum systems and controlling them is an immense technological challenge: they are inherently fragile; and information extracted from a quantum system necessarily disturbs the system itself. Of the various approaches to quantum technologies, photons are particularly appealing for their low-noise properties and ease of manipulation at the single qubit level. We have developed an integrated waveguide approach to photonic quantum circuits for high performance, miniaturization and scalability. We will described our latest progress in generating, manipulating and interacting single photons in waveguide circuits on silicon chips.

  20. 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

  1. 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 scanning-tunneling microscopy. I will review our experimental and theoretical progress in this plenary talk.[4pt] This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  2. Topological Quantum Computing Jacob Colbert

    E-print Network

    Rosner, Jonathan L.

    Topological Quantum Computing Jacob Colbert 3/5/2011 Contents 1 Introduction 1 2 Typical Quantum Computing 2 2.1 What is Quantum Computing? . . . . . . . . . . . . . . . . . . . . . . . 2 2.2 Quantum Error Channels . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4 Topological Quantum Computing

  3. 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.

  4. Quantum Robots and Quantum Computers

    E-print Network

    Paul Benioff

    1997-12-18

    Validation of a presumably universal theory, such as quantum mechanics, requires a quantum mechanical description of systems that carry out theoretical calculations and 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 environments. Some properties of these systems are discussed. A specific model based on the literature descriptions of quantum Turing machines is presented.

  5. Quantum Computing Abbas Edalat

    E-print Network

    Edalat, Abbas

    Quantum Computing Abbas Edalat 18 lectures + 9 tutorials Lecture Notes and Exercise Sheets London SW7 2BZ #12;Recommended Texts · Textbooks: ­ Jozef Gruska, Quantum Computing, (McGraw-Hill, 1999). ­ Michael A. Nielsen and Issac L. Chuang, Quantum Computation and Quantum Information, (Cambridge University

  6. Quantum Computing Abbas Edalat

    E-print Network

    Edalat, Abbas

    Quantum Computing Abbas Edalat 18 lectures + 9 tutorials Lecture Notes and Exercise Sheets London SW7 2BZ Recommended Texts . Textbooks: -- Jozef Gruska, Quantum Computing, (McGraw­Hill, 1999). -- Michael A. Nielsen and Issac L. Chuang, Quantum Computation and Quantum Information, (Cambridge University

  7. Integrable Quantum Computation

    E-print Network

    Yong Zhang

    2011-11-16

    Integrable quantum computation is defined as quantum computing via the integrable condition, in which two-qubit gates are either nontrivial unitary solutions of the Yang--Baxter equation or the Swap gate (permutation). To make the definition clear, in this article, we explore the physics underlying the quantum circuit model, and then present a unified description on both quantum computing via the Bethe ansatz and quantum computing via the Yang--Baxter equation.

  8. Blind topological measurement-based quantum computation

    E-print Network

    Tomoyuki Morimae; Keisuke Fujii

    2012-09-06

    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 0.0043, which is comparable to that (0.0075) of non-blind topological quantum computation. As the error per gate of the order 0.001 was already achieved in some experimental systems, our result implies that secure cloud quantum computation is within reach.

  9. Searching with Quantum Computers

    E-print Network

    Lov K. Grover

    2000-11-30

    This article introduces quantum computation by analogy with probabilistic computation. A basic description of the quantum search algorithm is given by representing the algorithm as a C program in a novel way.

  10. Quantum Computation: Introduction

    E-print Network

    de Wolf, Ronald

    "weird" effects: superposition, interference, entanglement Quantum Computation: Introduction ­ p. 2/2 #12, Benioff (±1982): What about quantum mechanical computers? Can we use those weird effects for useful

  11. Instrumentation for quantum computers

    E-print Network

    Huang, Wei-Han, 1979-

    2004-01-01

    Quantum computation poses challenging engineering and basic physics issues for the control of nanoscale systems. In particular, experimental realizations of up to seven-qubit NMR quantum computers have acutely illustrated ...

  12. 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.

  13. Optimal Blind Quantum Computation

    E-print Network

    Atul Mantri; Carlos A. Perez-Delgado; Joseph F. Fitzsimons

    2013-06-16

    Blind quantum computation allows a client with limited quantum capabilities to interact with a remote quantum computer to perform an arbitrary quantum computation, while keeping the description of that computation hidden from the remote quantum computer. While a number of protocols have been proposed in recent years, little is currently understood about the resources necessary to accomplish the task. Here we present general techniques for upper and lower bounding the quantum communication necessary to perform blind quantum computation, and use these techniques to establish a concrete bounds for common choices of the client's quantum capabilities. Our results show that the UBQC protocol of Broadbent, Fitzsimons and Kashefi [1], comes within a factor of 8/3 of optimal when the client is restricted to preparing single qubits. However, we describe a generalization of this protocol which requires exponentially less quantum communication when the client has a more sophisticated device.

  14. Quantum Analogue Computing

    E-print Network

    Vivien M. Kendon; Kae Nemoto; William J. Munro

    2010-01-13

    We briefly review what a quantum computer is, what it promises to do for us, and why it is so hard to build one. Among the first applications anticipated to bear fruit is quantum simulation of quantum systems. While most quantum computation is an extension of classical digital computation, quantum simulation differs fundamentally in how the data is encoded in the quantum computer. To perform a quantum simulation, the Hilbert space of the system to be simulated is mapped directly onto the Hilbert space of the (logical) qubits in the quantum computer. This type of direct correspondence is how data is encoded in a classical analogue computer. There is no binary encoding, and increasing precision becomes exponentially costly: an extra bit of precision doubles the size of the computer. This has important consequences for both the precision and error correction requirements of quantum simulation, and significant open questions remain about its practicality. It also means that the quantum version of analogue computers, continuous variable quantum computers (CVQC) becomes an equally efficient architecture for quantum simulation. Lessons from past use of classical analogue computers can help us to build better quantum simulators in future.

  15. 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 DOEs 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 DOEs mission as well as the additional research required to bring quantum computing to the point where it can have such impact.

  16. 'Photosynthetic' Quantum Computers?

    E-print Network

    Scott M. Hitchcock

    2001-08-20

    Do quantum computers already exist in Nature? It is proposed that they do. Photosynthesis is one example in which a 'quantum computer' component may play a role in the 'classical' world of complex biological systems. A 'translation' of the standard metabolic description of the 'front-end' light harvesting complex in photosynthesis into the language of quantum computers is presented. Biological systems represent an untapped resource for thinking about the design and operation of hybrid quantum-classical computers and expanding our current conceptions of what defines a 'quantum computer' in Nature.

  17. 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)

  18. Quantum computing via measurements only

    E-print Network

    Robert Raussendorf; Hans J. Briegel

    2000-10-07

    A quantum computer promises efficient processing of certain computational tasks that are intractable with classical computer technology. While basic principles of a quantum computer have been demonstrated in the laboratory, scalability of these systems to a large number of qubits, essential for practical applications such as the Shor algorithm, represents a formidable challenge. Most of the current experiments are designed to implement sequences of highly controlled interactions between selected particles (qubits), thereby following models of a quantum computer as a (sequential) network of quantum logic gates. Here we propose a different model of a scalable quantum computer. In our model, the entire resource for the quantum computation is provided initially in form of a specific entangled state (a so-called cluster state) of a large number of qubits. Information is then written onto the cluster, processed, and read out form the cluster by one-particle measurements only. The entangled state of the cluster thus serves as a universal substrate for any quantum computation. Cluster states can be created efficiently in any system with a quantum Ising-type interaction (at very low temperatures) between two-state particles in a lattice configuration.

  19. Authorized quantum computation

    E-print Network

    Yu Tanaka; Mio Murao

    2009-03-12

    We present authorized quantum computation, where only a user with a non-cloneable quantum authorization key can perform a unitary operation created by an authenticated programmer. The security of our authorized quantum computation is based on the quantum computational complexity problem of forging the keys from an obfuscated quantum gate sequence. Under the assumption of the existence of a \\textit{sufficiently-random gate shuffling algorithm}, the problem is shown to be in the NQP (Non-deterministic Quantum Polynomial)-hard class by reducing it to a NQP-Complete problem, the exact non-identity check problem. Therefore, our authorized quantum computation can be computationally secure against attacks using quantum computers.

  20. Continuous-variable blind quantum computation

    E-print Network

    Tomoyuki Morimae

    2012-12-05

    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 qubit 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.

  1. Quantum Computing since Democritus

    NASA Astrophysics Data System (ADS)

    Aaronson, Scott

    2013-03-01

    1. Atoms and the void; 2. Sets; 3. Gdel, 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.

  2. Topological Quantum Computation Zhenghan Wang

    E-print Network

    Rowell, Eric C.

    Topological Quantum Computation Zhenghan Wang Microsoft Station Q & UC Sana Barbara Texas, March 26, 2015 #12;Classical Physics Turing Model Quantum Mechanics Quantum Computing Quantum Field Theory ??? String Theory ?????? Quantum field computing is the same as quantum computing. True for TQFTs (Freedman

  3. Ancilla-Driven Universal Blind Quantum Computation

    E-print Network

    Takahiro Sueki; Takeshi Koshiba; Tomoyuki Morimae

    2013-04-02

    Blind quantum computation is a new quantum secure protocol, which enables Alice who does not have enough quantum technology to delegate her computation to Bob who has a fully-fledged quantum power without revealing her input, output and algorithm. So far, blind quantum computation has been considered only for the circuit model and the measurement-based model. Here we consider the possibility and the limitation of blind quantum computation in the ancilla-driven model, which is a hybrid of the circuit and the measurement-based models.

  4. 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.

  5. Cloning and quantum computation

    E-print Network

    Ernesto F. Galvao; Lucien Hardy

    2000-02-18

    We discuss how quantum information distribution can improve the performance of some quantum computation tasks. This distribution can be naturally implemented with different types of quantum cloning procedures. We give two examples of tasks for which cloning provides some enhancement in performance, and briefly discuss possible extensions of the idea.

  6. Quantum computing Hamiltonian cycles

    E-print Network

    T. Rudolph

    1996-03-03

    An algorithm for quantum computing Hamiltonian cycles of simple, cubic, bipartite graphs is discussed. It is shown that it is possible to evolve a quantum computer into an entanglement of states which map onto the set of all possible paths originating from a chosen vertex, and furthermore to subsequently project out all states not corresponding to Hamiltonian cycles.

  7. 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.

  8. Quantum computation Samuel L. Braunstein

    E-print Network

    Braunstein, Samuel L.

    Quantum computation Samuel L. Braunstein Computer Science, University of York, York YO10 5DD, UK and logic gates 3.1. FANOUT and ERASE 3.2. Computation without ERASE 4. Elementary quantum notation 5. Logic gates for quantum bits 6. Logic gates in the laboratory 7. Model quantum computer and quantum code 8

  9. Quantum Holonomies for Quantum Computing

    E-print Network

    Jiannis Pachos; Paolo Zanardi

    2001-03-19

    Holonomic Quantum Computation (HQC) is an all-geometrical approach to quantum information processing. In the HQC strategy information is encoded in degenerate eigen-spaces of a parametric family of Hamiltonians. The computational network of unitary quantum gates is realized by driving adiabatically the Hamiltonian parameters along loops in a control manifold. By properly designing such loops the non-trivial curvature of the underlying bundle geometry gives rise to unitary transformations i.e., holonomies that implement the desired unitary transformations. Conditions necessary for universal QC are stated in terms of the curvature associated to the non-abelian gauge potential (connection) over the control manifold. In view of their geometrical nature the holonomic gates are robust against several kind of perturbations and imperfections. This fact along with the adiabatic fashion in which gates are performed makes in principle HQC an appealing way towards universal fault-tolerant QC.

  10. Universal blind quantum computation

    E-print Network

    Anne Broadbent; Joseph Fitzsimons; Elham Kashefi

    2009-12-12

    We present a protocol which allows a client to have a server carry out a quantum computation for her such that the client's inputs, outputs and computation remain perfectly private, and where she does not require any quantum computational power or memory. The client only needs to be able to prepare single qubits randomly chosen from a finite set and send them to the server, who has the balance of the required quantum computational resources. Our protocol is interactive: after the initial preparation of quantum states, the client and server use two-way classical communication which enables the client to drive the computation, giving single-qubit measurement instructions to the server, depending on previous measurement outcomes. Our protocol works for inputs and outputs that are either classical or quantum. We give an authentication protocol that allows the client to detect an interfering server; our scheme can also be made fault-tolerant. We also generalize our result to the setting of a purely classical client who communicates classically with two non-communicating entangled servers, in order to perform a blind quantum computation. By incorporating the authentication protocol, we show that any problem in BQP has an entangled two-prover interactive proof with a purely classical verifier. Our protocol is the first universal scheme which detects a cheating server, as well as the first protocol which does not require any quantum computation whatsoever on the client's side. The novelty of our approach is in using the unique features of measurement-based quantum computing which allows us to clearly distinguish between the quantum and classical aspects of a quantum computation.

  11. Quantum Computing and Nuclear Magnetic Resonance

    E-print Network

    J. A. Jones

    2001-06-12

    Quantum information processing is the use of inherently quantum mechanical phenomena to perform information processing tasks that cannot be achieved using conventional classical information technologies. One famous example is quantum computing, which would permit calculations to be performed that are beyond the reach of any conceivable conventional computer. Initially it appeared that actually building a quantum computer would be extremely difficult, but in the last few years there has been an explosion of interest in the use of techniques adapted from conventional liquid state nuclear magnetic resonance (NMR) experiments to build small quantum computers. After a brief introduction to quantum computing I will review the current state of the art, describe some of the topics of current interest, and assess the long term contribution of NMR studies to the eventual implementation of practical quantum computers capable of solving real computational problems.

  12. Quantum computational geometry

    NASA Astrophysics Data System (ADS)

    Lanzagorta, Marco; Uhlmann, Jeffrey K.

    2004-08-01

    The prospects for practical quantum computing have improved significantly over the past few years, and there is an increasing motivation for developing quantum algorithms to address problems that are presently impractical to solve using classical computing. In previous work we have indentified such problems in the areas of computer graphics applications, and we have derived quantum-based solutions. In this paper we examine quantum-based solutions to problems arising in the area of computational geometry. These types of problems are important in a variety of scientific, industrial and military applications such as large scale multi-object simulation, virtual reality systems, and multi-target tracking. In particular, we present quantum algorithms for multidimensional searches, convex hull construction, and collision detection.

  13. Experimental verification of quantum computations

    E-print Network

    Stefanie Barz; Joseph F. Fitzsimons; Elham Kashefi; Philip Walther

    2013-08-30

    Quantum computers are expected to offer substantial speedups over their classical counterparts and to solve problems that are intractable for classical computers. Beyond such practical significance, the concept of quantum computation opens up new fundamental questions, among them the issue whether or not quantum computations can be certified by entities that are inherently unable to compute the results themselves. Here we present the first experimental verification of quantum computations. We show, in theory and in experiment, how a verifier with minimal quantum resources can test a significantly more powerful quantum computer. The new verification protocol introduced in this work utilizes the framework of blind quantum computing and is independent of the experimental quantum-computation platform used. In our scheme, the verifier is only required to generate single qubits and transmit them to the quantum computer. We experimentally demonstrate this protocol using four photonic qubits and show how the verifier can test the computer's ability to perform measurement-based quantum computations.

  14. Quantum Computation: A Computer Science Perspective

    E-print Network

    Anders K. H. Bengtsson

    2005-11-30

    The theory of quantum computation is presented in a self contained way from a computer science perspective. The basics of classical computation and quantum mechanics is reviewed. The circuit model of quantum computation is presented in detail. Throughout there is an emphasis on the physical as well as the abstract aspects of computation and the interplay between them. This report is presented as a Master's thesis at the department of Computer Science and Engineering at G{\\"o}teborg University, G{\\"o}teborg, Sweden. The text is part of a larger work that is planned to include chapters on quantum algorithms, the quantum Turing machine model and abstract approaches to quantum computation.

  15. Duality and Recycling Computing in Quantum Computers

    E-print Network

    Gui Lu Long; Yang Liu

    2007-08-15

    Quantum computer possesses quantum parallelism and offers great computing power over classical computer \\cite{er1,er2}. As is well-know, a moving quantum object passing through a double-slit exhibits particle wave duality. A quantum computer is static and lacks this duality property. The recently proposed duality computer has exploited this particle wave duality property, and it may offer additional computing power \\cite{r1}. Simply put it, a duality computer is a moving quantum computer passing through a double-slit. A duality computer offers the capability to perform separate operations on the sub-waves coming out of the different slits, in the so-called duality parallelism. Here we show that an $n$-dubit duality computer can be modeled by an $(n+1)$-qubit quantum computer. In a duality mode, computing operations are not necessarily unitary. A $n$-qubit quantum computer can be used as an $n$-bit reversible classical computer and is energy efficient. Our result further enables a $(n+1)$-qubit quantum computer to run classical algorithms in a $O(2^n)$-bit classical computer. The duality mode provides a natural link between classical computing and quantum computing. Here we also propose a recycling computing mode in which a quantum computer will continue to compute until the result is obtained. These two modes provide new tool for algorithm design. A search algorithm for the unsorted database search problem is designed.

  16. Nature as quantum computer

    E-print Network

    David Ritz Finkelstein

    2012-01-08

    Set theory reduces all processes to assembly and disassembly. A similar architecture is proposed for nature as quantum computer. It resolves the classical space-time underlying Feynman diagrams into a quantum network of creation and annihilation processes, reducing kinematics to quantum statistics, and regularizing the Lie algebra of the Einstein diffeomorphism group. The usually separate and singular Lie algebras of kinematics, statistics, and conserved currents merge into one regular statistics Lie algebra.

  17. Quantum Disentanglement and Computation

    E-print Network

    Asher Peres

    1997-07-24

    Entanglement is essential for quantum computation. However, disentanglement is also necessary. It can be achieved without the need of classical operations (measurements). Two examples are analyzed: the discrete Fourier transform and error correcting codes.

  18. Towards Quantum Computational Logics

    NASA Astrophysics Data System (ADS)

    Ledda, Antonio; Sergioli, Giuseppe

    2010-12-01

    Quantum computational logics have recently stirred increasing attention (Cattaneo et al. in Math. Slovaca 54:87-108, 2004; Ledda et al. in Stud. Log. 82(2):245-270, 2006; Giuntini et al. in Stud. Log. 87(1):99-128, 2007). In this paper we outline their motivations and report on the state of the art of the approach to the logic of quantum computation that has been recently taken up and developed by our research group.

  19. Optical Quantum Computation

    E-print Network

    T. C. Ralph; G. J. Pryde

    2011-03-31

    We review the field of Optical Quantum Computation, considering the various implementations that have been proposed and the experimental progress that has been made toward realizing them. We examine both linear and nonlinear approaches and both particle and field encodings. In particular we discuss the prospects for large scale optical quantum computing in terms of the most promising physical architectures and the technical requirements for realizing them.

  20. Linear optical quantum computing with photonic qubits Pieter Kok*

    E-print Network

    Dowling, Jonathan P.

    Linear optical quantum computing with photonic qubits Pieter Kok* Department of Materials, Oxford-ku, Tokyo 101-8430, Japan T. C. Ralph Centre for Quantum Computer Technology, University of Queensland, St-4242, USA G. J. Milburn Centre for Quantum Computer Technology, University of Queensland, St. Lucia

  1. Alternative models for quantum computation/

    E-print Network

    Lin, Cedric Yen-Yu

    2015-01-01

    We propose and study two new computational models for quantum computation, and infer new insights about the circumstances that give quantum computers an advantage over classical ones. The bomb query complexity model is a ...

  2. Robustness of Adiabatic Quantum Computing

    E-print Network

    Seth Lloyd

    2008-05-18

    Adiabatic quantum computation for performing quantum computations such as Shor's algorithm is protected against thermal errors by an energy gap of size $O(1/n)$, where $n$ is the length of the computation to be performed.

  3. Quantum Computing Robert Sizemore

    E-print Network

    Olszewski Jr., Edward A.

    a specific problem. The mathematician Alan Turing (1912-1954) devised a hypothetical machine that could Computation Turing machine model #12;Outline (cont.) Circuit model Quantum Computation Qubits Circuit model execute any algorithm called a Turing Machine. #12;Turing Machine Tape infinite number of cells, every

  4. Quantum computational webs

    E-print Network

    D. Gross; J. Eisert

    2010-05-01

    We introduce the notion of quantum computational webs: These are quantum states universal for measurement-based computation which can be built up from a collection of simple primitives. The primitive elements - reminiscent of building blocks in a construction kit - are (i) states on a one-dimensional chain of systems ("computational quantum wires") with the power to process one logical qubit and (ii) suitable couplings which connect the wires to a computationally universal "web". All elements are preparable by nearest-neighbor interactions in a single pass - a type of operation well-suited for a number of physical architectures. We provide a complete classification of qubit wires. This is first instance where a physically well-motivated class of universal resources can be fully understood. Finally, we sketch possible realizations in superlattices, and explore the power of coupling mechanisms based on Ising or exchange-interactions.

  5. From the Academy Quantum computing

    E-print Network

    Bai, Fengshan

    From the Academy Quantum computing Shu-Shen Li* , Gui-Lu Long§¶ , Feng-Shan Bai , Song-Lin Feng University, Beijing 100084, China Quantum computing is a quickly growing research field. This article introduces the basic concepts of quantum computing, recent developments in quantum searching, and decoherence

  6. Universal computation by quantum walk.

    PubMed

    Childs, Andrew M

    2009-05-01

    In some of the earliest work on quantum computing, Feynman showed how to implement universal quantum computation with a time-independent Hamiltonian. I show that this remains possible even if the Hamiltonian is restricted to be the adjacency matrix of a low-degree graph. Thus quantum walk can be regarded as a universal computational primitive, with any quantum computation encoded in some graph. The main idea is to implement quantum gates by scattering processes. PMID:19518851

  7. Quantum teleportation and survey technology

    NASA Astrophysics Data System (ADS)

    Wang, Zhiguo

    2010-10-01

    Quantum teleportation is an important component element of quantum information theory and is an effective method to realize quantum communication. This paper presents the realization method and survey technology of quantum teleportation, introduces the theory and experiment research process of quantum communication field and its broad prospect.

  8. Delegating Private Quantum Computations

    E-print Network

    Anne Broadbent

    2015-06-03

    We give a protocol for the delegation of quantum computation on encrypted data. More specifically, we show that in a client-server scenario, where the client holds the encryption key for an encrypted quantum register held by the server, it is possible for the server to perform a universal set of quantum gates on the quantum data. All Clifford group gates are non-interactive, while the remaining non-Clifford group gate that we implement (the p/8 gate) requires the client to prepare and send a single random auxiliary qubit (chosen among four possibilities), and exchange classical communication. This construction improves on previous work, which requires either multiple auxiliary qubits or two-way quantum communication. Using a reduction to an entanglement-based protocol, we show privacy against any adversarial server according to a simulation-based security definition.

  9. Optical Quantum Computing

    E-print Network

    Jeremy L. O'Brien

    2008-03-11

    In 2001 all-optical quantum computing became feasible with the discovery that scalable quantum computing is possible using only single photon sources, linear optical elements, and single photon detectors. Although it was in principle scalable, the massive resource overhead made the scheme practically daunting. However, several simplifications were followed by proof-of-principle demonstrations, and recent approaches based on cluster states or error encoding have dramatically reduced this worrying resource overhead, making an all-optical architecture a serious contender for the ultimate goal of a large-scale quantum computer. Key challenges will be the realization of high-efficiency sources of indistinguishable single photons, low-loss, scalable optical circuits, high efficiency single photon detectors, and low-loss interfacing of these components.

  10. Coalgebraic Semantics for Quantum Computation

    E-print Network

    Bosma, Wieb

    Coalgebraic Semantics for Quantum Computation Frank Roumen Master's thesis in Mathematics July 2012 systems . . . . . . . . . . . . . . . . . . . . . . . . 20 2 Quantum computation 25 2.1 Hilbert spaces to perform computations on a quantum ver- sion of data, we obtain a type of computation that is fundamentally

  11. Quantum Computation Models Foundational Problems

    E-print Network

    Rowell, Eric C.

    Quantum Computation Models Foundational Problems Qualitative Questions Conjectural Answer to All Questions Locality in Quantum Computation, II Eric Rowell1 with Z. Wang2, C. Galindo3, S.-M. Hong4 1:Texas A Computation, II #12;Quantum Computation Models Foundational Problems Qualitative Questions Conjectural Answer

  12. Lecture notes on Optical Quantum Computing

    E-print Network

    Pieter Kok

    2007-05-29

    A quantum computer is a machine that can perform certain calculations much faster than a classical computer by using the laws of quantum mechanics. Quantum computers do not exist yet, because it is extremely difficult to control quantum mechanical systems to the necessary degree. What is more, we do at this moment not know which physical system is the best suited for making a quantum computer (although we have some ideas). It is likely that a mature quantum information processing technology will use (among others) light, because photons are ideal carriers for quantum information. These notes are an expanded version of the five lectures I gave on the possibility of making a quantum computer using light, at the Summer School in Theoretical Physics in Durban, 14-24 January, 2007. There are quite a few proposals using light for quantum computing, and I can highlight only a few here. I will focus on photonic qubits, and leave out continuous variables completely. I assume that the reader is familiar with basic quantum mechanics and introductory quantum computing.

  13. I, Quantum Robot: Quantum Mind control on a Quantum Computer

    E-print Network

    Paola Zizzi

    2009-05-28

    The logic which describes quantum robots is not orthodox quantum logic, but a deductive calculus which reproduces the quantum tasks (computational processes, and actions) taking into account quantum superposition and quantum entanglement. A way toward the realization of intelligent quantum robots is to adopt a quantum metalanguage to control quantum robots. A physical implementation of a quantum metalanguage might be the use of coherent states in brain signals.

  14. Quantum Chaos and Quantum Computing Structures

    E-print Network

    Carlos Pedro Gonalves

    2012-08-13

    A system of quantum computing structures is introduced and proven capable of making emerge, on average, the orbits of classical bounded nonlinear maps on \\mathbb{C} through the iterative action of path-dependent quantum gates. The effects of emerging nonlinear dynamics and chaos upon the quantum averages of relevant observables and quantum probabilities are exemplified for a version of Chirikov's standard map on \\mathbb{C} . Both the individual orbits and ensemble properties are addressed so that the Poincar\\'e map for Chirikov's standard map, in the current quantum setting, is reinterpreted in terms of a quantum ensemble which is then formally introduced within the formalized system of quantum computing structures, in terms of quantum register machines, revealing three phases of quantum ensemble dynamics: the regular, the chaotic and an intermediate phase called complex quantum stochastic phase which shares similarities to the edge of chaos notion from classical cellular automata and classical random boolean networks' evolutionary computation.

  15. 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.

  16. 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.

  17. Quantum Chaos Border for Quantum Computing

    E-print Network

    B. Georgeot; D. L. Shepelyansky

    2000-01-17

    We study a generic model of quantum computer, composed of many qubits coupled by short-range interaction. Above a critical interqubit coupling strength, quantum chaos sets in, leading to quantum ergodicity of the computer eigenstates. In this regime the noninteracting qubit structure disappears, the eigenstates become complex and the operability of the computer is destroyed. Despite the fact that the spacing between multi-qubit states drops exponentially with the number of qubits $n$, we show that the quantum chaos border decreases only linearly with $n$. This opens a broad parameter region where the efficient operation of a quantum computer remains possible.

  18. 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.

  19. Quantum++ - A C++11 quantum computing library

    E-print Network

    Vlad Gheorghiu

    2014-12-15

    Quantum++ is a general-purpose multi-threaded quantum computing library written in C++11 and composed solely of header files. The library is not restricted to qubit systems or specific quantum information processing tasks, being capable of simulating arbitrary quantum processes. The main design factors taken in consideration were ease of use, portability, and performance.

  20. Quantum++ - A C++11 quantum computing library

    E-print Network

    Gheorghiu, Vlad

    2014-01-01

    Quantum++ is a general-purpose multi-threaded quantum computing library written in C++11 and composed solely of header files. The library is not restricted to qubit systems or specific quantum information processing tasks, being capable of simulating arbitrary quantum processes. The main design factors taken in consideration were ease of use, portability, and performance.

  1. An Introduction to Quantum Computing

    E-print Network

    Noson S. Yanofsky

    2007-08-02

    Quantum Computing is a new and exciting field at the intersection of mathematics, computer science and physics. It concerns a utilization of quantum mechanics to improve the efficiency of computation. Here we present a gentle introduction to some of the ideas in quantum computing. The paper begins by motivating the central ideas of quantum mechanics and quantum computation with simple toy models. From there we move on to a formal presentation of the small fraction of (finite dimensional) quantum mechanics that we will need for basic quantum computation. Central notions of quantum architecture (qubits and quantum gates) are described. The paper ends with a presentation of one of the simplest quantum algorithms: Deutsch's algorithm. Our presentation demands neither advanced mathematics nor advanced physics.

  2. Parallel Quantum Computing in a Single Ensemble Quantum Computer

    E-print Network

    Gui Lu Long; Li Xiao

    2003-07-08

    We propose a parallel quantum computing mode for ensemble quantum computer. In this mode, some qubits can be in pure states while other qubits in mixed states. It enables a single ensemble quantum computer to perform $"$single-instruction-multi-data" type of parallel computation. In Grover's algorithm and Shor's algorithm, parallel quantum computing can provide additional speedup. In addition, it also makes a fuller use of qubit resources in an ensemble quantum computer. As a result, some qubits discarded in the preparation of an effective pure state in the Schulman-Varizani, and the Cleve-DiVincenzo algorithms can be re-utilized.

  3. QUANTUM COMPUTATION * Dorit Aharonov

    E-print Network

    Aharonov, Dorit

    , such as the transition from quantum to classical physics. 1 Overview Since ancient times, humanity has been seeking tools The computation part of the process is inevitably performed by a dynamical physical system, evolving in time is a masterpiece of art, and is still in the process of building, after almost a hundred years. The church

  4. 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.

  5. Layered architecture for quantum computing

    E-print Network

    N. Cody Jones; Rodney Van Meter; Austin G. Fowler; Peter L. McMahon; Jungsang Kim; Thaddeus D. Ladd; Yoshihisa Yamamoto

    2012-09-27

    We develop a layered quantum computer architecture, which is a systematic framework for tackling the individual challenges of developing a quantum computer while constructing a cohesive device design. We discuss many of the prominent techniques for implementing circuit-model quantum computing and introduce several new methods, with an emphasis on employing surface code quantum error correction. In doing so, we propose a new quantum computer architecture based on optical control of quantum dots. The timescales of physical hardware operations and logical, error-corrected quantum gates differ by several orders of magnitude. By dividing functionality into layers, we can design and analyze subsystems independently, demonstrating the value of our layered architectural approach. Using this concrete hardware platform, we provide resource analysis for executing fault-tolerant quantum algorithms for integer factoring and quantum simulation, finding that the quantum dot architecture we study could solve such problems on the timescale of days.

  6. Quantum Computing with Superqubits

    E-print Network

    Leonardo Castellani; Pietro Antonio Grassi; Luca Sommovigo

    2010-01-21

    We analyze some aspects of quantum computing with super-qubits (squbits). We propose the analogue of a superfield formalism, and give a physical interpretation for the Grassmann coefficients in the squbit expansion as fermionic creation operators of an auxiliary quantum system. In the simplest case the squbit is a superposition of one Bose X Bose and one Fermi X Fermi state, and its norm is invariant under a U(2) group realized with Clifford-valued matrices. This case can be generalized to a superposition of n_B bosonic and n_F fermionic states, with a norm invariant under U(n_B + n_F). Entanglement between squbits, super quantum gates and teleportation are discussed.

  7. Quantum computing of semiclassical formulas

    E-print Network

    B. Georgeot; O. Giraud

    2008-01-30

    We show that semiclassical formulas such as the Gutzwiller trace formula can be implemented on a quantum computer more efficiently than on a classical device. We give explicit quantum algorithms which yield quantum observables from classical trajectories, and which alternatively test the semiclassical approximation by computing classical actions from quantum evolution. The gain over classical computation is in general quadratic, and can be larger in some specific cases.

  8. Quantum Computation vs. Firewalls

    E-print Network

    Daniel Harlow; Patrick Hayden

    2013-04-06

    In this paper we discuss quantum computational restrictions on the types of thought experiments recently used by Almheiri, Marolf, Polchinski, and Sully to argue against the smoothness of black hole horizons. We argue that the quantum computations required to do these experiments take a time which is exponential in the entropy of the black hole under study, and we show that for a wide variety of black holes this prevents the experiments from being done. We interpret our results as motivating a broader type of non-locality than is usually considered in the context of black hole thought experiments, and claim that once this type of non-locality is allowed there may be no need for firewalls. Our results do not threaten the unitarity of of black hole evaporation or the ability of advanced civilizations to test it.

  9. 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 integralanyons 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.

  10. Quantum Computing Spacetime

    E-print Network

    P. A. Zizzi

    2002-04-02

    A causal set C can describe a discrete spacetime, but this discrete spacetime is not quantum, because C is endowed with Boolean logic, as it does not allow cycles. In a quasi-ordered set Q, cycles are allowed. In this paper, we consider a subset QC of a quasi-ordered set Q, whose elements are all the cycles. In QC, which is endowed with quantum logic, each cycle of maximal outdegree N in a node, is associated with N entangled qubits. Then QC describes a quantum computing spacetime. This structure, which is non-local and non-casual, can be understood as a proto-spacetime. Micro-causality and locality can be restored in the subset U of Q whose elements are unentangled qubits which we interpret as the states of quantum spacetime. The mapping of quantum spacetime into proto-spacetime is given by the action of the XOR gate. Moreover, a mapping is possible from the Boolean causal set into U by the action of the Hadamard gate. In particular, the causal order defined on the elements of U induces the causal evolution of spin networks.

  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 Walk Schemes for Universal Quantum Computation

    NASA Astrophysics Data System (ADS)

    Underwood, Michael S.

    Random walks are a powerful tool for the efficient implementation of algorithms in classical computation. Their quantum-mechanical analogues, called quantum walks, hold similar promise. Quantum walks provide a model of quantum computation that has recently been shown to be equivalent in power to the standard circuit model. As in the classical case, quantum walks take place on graphs and can undergo discrete or continuous evolution, though quantum evolution is unitary and therefore deterministic until a measurement is made. This thesis considers the usefulness of continuous-time quantum walks to quantum computation from the perspectives of both their fundamental power under various formulations, and their applicability in practical experiments. In one extant scheme, logical gates are effected by scattering processes. The results of an exhaustive search for single-qubit operations in this model are presented. It is shown that the number of distinct operations increases exponentially with the number of vertices in the scattering graph. A catalogue of all graphs on up to nine vertices that implement single-qubit unitaries at a specific set of momenta is included in an appendix. I develop a novel scheme for universal quantum computation called the discontinuous quantum walk, in which a continuous-time quantum walker takes discrete steps of evolution via perfect quantum state transfer through small 'widget' graphs. The discontinuous quantum-walk scheme requires an exponentially sized graph, as do prior discrete and continuous schemes. To eliminate the inefficient vertex resource requirement, a computation scheme based on multiple discontinuous walkers is presented. In this model, n interacting walkers inhabiting a graph with 2n vertices can implement an arbitrary quantum computation on an input of length n, an exponential savings over previous universal quantum walk schemes. This is the first quantum walk scheme that allows for the application of quantum error correction. The many-particle quantum walk can be viewed as a single quantum walk undergoing perfect state transfer on a larger weighted graph, obtained via equitable partitioning. I extend this formalism to non-simple graphs. Examples of the application of equitable partitioning to the analysis of quantum walks and many-particle quantum systems are discussed.

  13. Decoherence in adiabatic quantum computation

    NASA Astrophysics Data System (ADS)

    Albash, Tameem; Lidar, Daniel A.

    2015-06-01

    Recent experiments with increasingly larger numbers of qubits have sparked renewed interest in adiabatic quantum computation, and in particular quantum annealing. A central question that is repeatedly asked is whether quantum features of the evolution can survive over the long time scales used for quantum annealing relative to standard measures of the decoherence time. We reconsider the role of decoherence in adiabatic quantum computation and quantum annealing using the adiabatic quantum master-equation formalism. We restrict ourselves to the weak-coupling and singular-coupling limits, which correspond to decoherence in the energy eigenbasis and in the computational basis, respectively. We demonstrate that decoherence in the instantaneous energy eigenbasis does not necessarily detrimentally affect adiabatic quantum computation, and in particular that a short single-qubit T2 time need not imply adverse consequences for the success of the quantum adiabatic algorithm. We further demonstrate that boundary cancellation methods, designed to improve the fidelity of adiabatic quantum computing in the closed-system setting, remain beneficial in the open-system setting. To address the high computational cost of master-equation simulations, we also demonstrate that a quantum Monte Carlo algorithm that explicitly accounts for a thermal bosonic bath can be used to interpolate between classical and quantum annealing. Our study highlights and clarifies the significantly different role played by decoherence in the adiabatic and circuit models of quantum computing.

  14. Decoherence in adiabatic quantum computation

    E-print Network

    Tameem Albash; Daniel A. Lidar

    2015-06-19

    Recent experiments with increasingly larger numbers of qubits have sparked renewed interest in adiabatic quantum computation, and in particular quantum annealing. A central question that is repeatedly asked is whether quantum features of the evolution can survive over the long time-scales used for quantum annealing relative to standard measures of the decoherence time. We reconsider the role of decoherence in adiabatic quantum computation and quantum annealing using the adiabatic quantum master equation formalism. We restrict ourselves to the weak-coupling and singular-coupling limits, which correspond to decoherence in the energy eigenbasis and in the computational basis, respectively. We demonstrate that decoherence in the instantaneous energy eigenbasis does not necessarily detrimentally affect adiabatic quantum computation, and in particular that a short single-qubit $T_2$ time need not imply adverse consequences for the success of the quantum adiabatic algorithm. We further demonstrate that boundary cancellation methods, designed to improve the fidelity of adiabatic quantum computing in the closed system setting, remain beneficial in the open system setting. To address the high computational cost of master equation simulations, we also demonstrate that a quantum Monte Carlo algorithm that explicitly accounts for a thermal bosonic bath can be used to interpolate between classical and quantum annealing. Our study highlights and clarifies the significantly different role played by decoherence in the adiabatic and circuit models of quantum computing.

  15. Motivation: Quantum Computation Sequences of Representations

    E-print Network

    Rowell, Eric C.

    Motivation: Quantum Computation Sequences of Representations Outlook Localizing Unitary Braid Representations #12;Motivation: Quantum Computation Sequences of Representations Outlook Outline 1 Motivation: Quantum Computation Quantum Circuit and Topological Models 2 Sequences of Representations Matrix

  16. Computational equivalence between quantum Turing machines

    E-print Network

    Møller, Jesper Michael

    Computational equivalence between quantum Turing machines and quantum circuit families Christian by quantum circuit families . . . . . . . . . . . 18 3 Computational equivalence 19 3.1 Encoding with my master's study was to obtain a knowledge about the theoretical foundation of quantum computing

  17. Computer Technology for Industry

    NASA Technical Reports Server (NTRS)

    1979-01-01

    In this age of the computer, more and more business firms are automating their operations for increased efficiency in a great variety of jobs, from simple accounting to managing inventories, from precise machining to analyzing complex structures. In the interest of national productivity, NASA is providing assistance both to longtime computer users and newcomers to automated operations. Through a special technology utilization service, NASA saves industry time and money by making available already developed computer programs which have secondary utility. A computer program is essentially a set of instructions which tells the computer how to produce desired information or effect by drawing upon its stored input. Developing a new program from scratch can be costly and time-consuming. Very often, however, a program developed for one purpose can readily be adapted to a totally different application. To help industry take advantage of existing computer technology, NASA operates the Computer Software Management and Information Center (COSMIC)(registered TradeMark),located at the University of Georgia. COSMIC maintains a large library of computer programs developed for NASA, the Department of Defense, the Department of Energy and other technology-generating agencies of the government. The Center gets a continual flow of software packages, screens them for adaptability to private sector usage, stores them and informs potential customers of their availability.

  18. Liquid-State NMR Quantum Computing

    E-print Network

    Liquid-State NMR Quantum Computing Lieven M. K. Vandersypen TU Delft, Delft, the Netherlands Isaac, Dortmund, Germany 1 Introduction 1 2 Quantum Computation 1 3 NMR Quantum Computers 5 4 Summary of doing computation becomes possible, which is known as quantum computation (QC). Quantum computing

  19. Quantum Computation and Many Worlds

    E-print Network

    Clare Hewitt-Horsman

    2008-02-21

    An Everett (`Many Worlds') interpretation of quantum mechanics due to Saunders and Zurek is presented in detail. This is used to give a physical description of the process of a quantum computation. Objections to such an understanding are discussed.

  20. Self-correcting quantum computers

    E-print Network

    Chhajlany, R W

    Is the notion of a quantum computer (QC) resilient to thermal noise unphysical? We address this question from a constructive perspective and show that local quantum Hamiltonian models provide self-correcting QCs. To this ...

  1. Multi-party Quantum Computation

    E-print Network

    Adam Smith

    2001-11-06

    We investigate definitions of and protocols for multi-party quantum computing in the scenario where the secret data are quantum systems. We work in the quantum information-theoretic model, where no assumptions are made on the computational power of the adversary. For the slightly weaker task of verifiable quantum secret sharing, we give a protocol which tolerates any t < n/4 cheating parties (out of n). This is shown to be optimal. We use this new tool to establish that any multi-party quantum computation can be securely performed as long as the number of dishonest players is less than n/6.

  2. Experimental Quantum Computing without Entanglement B. P. Lanyon,* M. Barbieri,

    E-print Network

    White, Andrew G.

    efficient parameter estimation at the quantum metrology limit [7]. That such a useful tool could be builtExperimental Quantum Computing without Entanglement B. P. Lanyon,* M. Barbieri, M. P. Almeida, and A. G. White Department of Physics and Centre for Quantum Computer Technology, University

  3. Applications of quantum chaos to realistic quantum computations and sound treatment on quantum computers

    E-print Network

    Shepelyansky, Dima

    Applications of quantum chaos to realistic quantum computations and sound treatment on quantum dynamics on quantum computers in presence of imper- fections. The effects of random errors and static computer can be recognized and restored with a minimal number of measurements in presence of random quantum

  4. Blind Quantum Computation

    E-print Network

    Pablo Arrighi; Louis Salvail

    2006-06-06

    We investigate the possibility of "having someone carry out the work of executing a function for you, but without letting him learn anything about your input". Say Alice wants Bob to compute some known function f upon her input x, but wants to prevent Bob from learning anything about x. The situation arises for instance if client Alice has limited computational resources in comparison with mistrusted server Bob, or if x is an inherently mobile piece of data. Could there be a protocol whereby Bob is forced to compute f(x) "blindly", i.e. without observing x? We provide such a blind computation protocol for the class of functions which admit an efficient procedure to generate random input-output pairs, e.g. factorization. The cheat-sensitive security achieved relies only upon quantum theory being true. The security analysis carried out assumes the eavesdropper performs individual attacks. Keywords: Secure Circuit Evaluation, Secure Two-party Computation, Information Hiding, Information gain vs disturbance.

  5. Quantum Computing: Pro and Con

    E-print Network

    John Preskill

    1997-08-26

    I assess the potential of quantum computation. Broad and important applications must be found to justify construction of a quantum computer; I review some of the known quantum algorithms and consider the prospects for finding new ones. Quantum computers are notoriously susceptible to making errors; I discuss recently developed fault-tolerant procedures that enable a quantum computer with noisy gates to perform reliably. Quantum computing hardware is still in its infancy; I comment on the specifications that should be met by future hardware. Over the past few years, work on quantum computation has erected a new classification of computational complexity, has generated profound insights into the nature of decoherence, and has stimulated the formulation of new techniques in high-precision experimental physics. A broad interdisciplinary effort will be needed if quantum computers are to fulfill their destiny as the world's fastest computing devices. (This paper is an expanded version of remarks that were prepared for a panel discussion at the ITP Conference on Quantum Coherence and Decoherence, 17 December 1996.)

  6. Geometrical perspective on quantum states and quantum computation

    E-print Network

    Zeqian Chen

    2013-11-20

    We interpret quantum computing as a geometric evolution process by reformulating finite quantum systems via Connes' noncommutative geometry. In this formulation, quantum states are represented as noncommutative connections, while gauge transformations on the connections play a role of unitary quantum operations. Thereby, a geometrical model for quantum computation is presented, which is equivalent to the quantum circuit model. This result shows a geometric way of realizing quantum computing and as such, provides an alternative proposal of building a quantum computer.

  7. 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.

  8. Quantum computing in a piece of glass

    E-print Network

    Warner A. Miller; Grigoriy Kreymerman; Christopher Tison; Paul M. Alsing; Jonathan R. McDonald

    2011-12-15

    Quantum gates and simple quantum algorithms can be designed utilizing the diffraction phenomena of a photon within a multiplexed holographic element. The quantum eigenstates we use are the photon's linear momentum (LM) as measured by the number of waves of tilt across the aperture. Two properties of quantum computing within the circuit model make this approach attractive. First, any conditional measurement can be commuted in time with any unitary quantum gate - the timeless nature of quantum computing. Second, photon entanglement can be encoded as a superposition state of a single photon in a higher-dimensional state space afforded by LM. Our theoretical and numerical results indicate that OptiGrate's photo-thermal refractive (PTR) glass is an enabling technology. We will review our previous design of a quantum projection operator and give credence to this approach on a representative quantum gate grounded on coupled-mode theory and numerical simulations, all with parameters consistent with PTR glass. We discuss the strengths (high efficiencies, robustness to environment) and limitations (scalability, crosstalk) of this technology. While not scalable, the utility and robustness of such optical elements for broader quantum information processing applications can be substantial.

  9. Quantum computation beyond the circuit model

    E-print Network

    Jordan, Stephen Paul

    2008-01-01

    The quantum circuit model is the most widely used model of quantum computation. It provides both a framework for formulating quantum algorithms and an architecture for the physical construction of quantum computers. However, ...

  10. The pre-history of quantum computation

    E-print Network

    P. H. Potgieter

    2004-11-16

    The main ideas behind developments in the theory and technology of quantum computation were formulated in the late 1970s and early 1980s by two physicists in the West and a mathematician in the former Soviet Union. It is not generally known in the West that the subject has roots in the Russian technical literature. The author hopes to present as impartial a synthesis as possible of the early history of thought on this subject. The role of reversible and irreversible computational processes is examined briefly as it relates to the origins of quantum computing and the so-called Information Paradox in physics.

  11. Categorical Models for Quantum Computing

    E-print Network

    Murawski, Andrzej

    Categorical Models for Quantum Computing Linde Wester Worcester College University of Oxford, that made me understand quantum theory and quantum information conceptually, on an abstract level. They led and simultaneously teaching me all the important lessons that I needed for this. I also want to thank Bob, who has

  12. Programming a Topological Quantum Computer

    E-print Network

    Simon J. Devitt; Kae Nemoto

    2012-09-07

    Topological quantum computing has recently proven itself to be a powerful computational model when constructing viable architectures for large scale computation. The topological model is constructed from the foundation of a error correction code, required to correct for inevitable hardware faults that will exist for a large scale quantum device. It is also a measurement based model of quantum computation, meaning that the quantum hardware is responsible only for the construction of a large, computationally universal quantum state. This quantum state is then strategically consumed, allowing for the realisation of a fully error corrected quantum algorithm. The number of physical qubits needed by the quantum hardware and the amount of time required to implement an algorithm is dictated by the manner in which this universal quantum state is consumed. In this paper we examine the problem of algorithmic optimisation in the topological lattice and introduce the required elements that will be needed when designing a classical software package to compile and implement a large scale algorithm on a topological quantum computer.

  13. Simulating chemistry using quantum computers

    E-print Network

    Ivan Kassal; James D. Whitfield; Alejandro Perdomo-Ortiz; Man-Hong Yung; Aln Aspuru-Guzik

    2010-07-15

    The difficulty of simulating quantum systems, well-known to quantum chemists, prompted the idea of quantum computation. One can avoid the steep scaling associated with the exact simulation of increasingly large quantum systems on conventional computers, by mapping the quantum system to another, more controllable one. In this review, we discuss to what extent the ideas in quantum computation, now a well-established field, have been applied to chemical problems. We describe algorithms that achieve significant advantages for the electronic-structure problem, the simulation of chemical dynamics, protein folding, and other tasks. Although theory is still ahead of experiment, we outline recent advances that have led to the first chemical calculations on small quantum information processors.

  14. Quantum technology and cryptology for information security

    NASA Astrophysics Data System (ADS)

    Naqvi, Syed; Riguidel, Michel

    2007-04-01

    Cryptology and information security are set to play a more prominent role in the near future. In this regard, quantum communication and cryptography offer new opportunities to tackle ICT security. Quantum Information Processing and Communication (QIPC) is a scientific field where new conceptual foundations and techniques are being developed. They promise to play an important role in the future of information Security. It is therefore essential to have a cross-fertilizing development between quantum technology and cryptology in order to address the security challenges of the emerging quantum era. In this article, we discuss the impact of quantum technology on the current as well as future crypto-techniques. We then analyse the assumptions on which quantum computers may operate. Then we present our vision for the distribution of security attributes using a novel form of trust based on Heisenberg's uncertainty; and, building highly secure quantum networks based on the clear transmission of single photons and/or bundles of photons able to withstand unauthorized reading as a result of secure protocols based on the observations of quantum mechanics. We argue how quantum cryptographic systems need to be developed that can take advantage of the laws of physics to provide long-term security based on solid assumptions. This requires a structured integration effort to deploy quantum technologies within the existing security infrastructure. Finally, we conclude that classical cryptographic techniques need to be redesigned and upgraded in view of the growing threat of cryptanalytic attacks posed by quantum information processing devices leading to the development of post-quantum cryptography.

  15. 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.

  16. Quantum technology and its applications

    SciTech Connect

    Boshier, Malcolm; Berkeland, Dana; Govindan, Tr; Abo - Shaeer, Jamil

    2010-12-10

    Quantum states of matter can be exploited as high performance sensors for measuring time, gravity, rotation, and electromagnetic fields, and quantum states of light provide powerful new tools for imaging and communication. Much attention is being paid to the ultimate limits of this quantum technology. For example, it has already been shown that exotic quantum states can be used to measure or image with higher precision or higher resolution or lower radiated power than any conventional technologies, and proof-of-principle experiments demonstrating measurement precision below the standard quantum limit (shot noise) are just starting to appear. However, quantum technologies have another powerful advantage beyond pure sensing performance that may turn out to be more important in practical applications: the potential for building devices with lower size/weight/power (SWaP) and cost requirements than existing instruments. The organizers of Quantum Technology Applications Workshop (QTAW) have several goals: (1) Bring together sponsors, researchers, engineers and end users to help build a stronger quantum technology community; (2) Identify how quantum systems might improve the performance of practical devices in the near- to mid-term; and (3) Identify applications for which more long term investment is necessary to realize improved performance for realistic applications. To realize these goals, the QTAW II workshop included fifty scientists, engineers, managers and sponsors from academia, national laboratories, government and the private-sector. The agenda included twelve presentations, a panel discussion, several breaks for informal exchanges, and a written survey of participants. Topics included photon sources, optics and detectors, squeezed light, matter waves, atomic clocks and atom magnetometry. Corresponding applications included communication, imaging, optical interferometry, navigation, gravimetry, geodesy, biomagnetism, and explosives detection. Participants considered the physics and engineering of quantum and conventional technologies, and how quantum techniques could (or could not) overcome limitations of conventional systems. They identified several auxiliary technologies that needed to be further developed in order to make quantum technology more accessible. Much of the discussion also focused on specific applications of quantum technology and how to push the technology into broader communities, which would in turn identify new uses of the technology. Since our main interest is practical improvement of devices and techniques, we take a liberal definition of 'quantum technology': a system that utilizes preparation and measurement of a well-defined coherent quantum state. This nomenclature encompasses features broader than entanglement, squeezing or quantum correlations, which are often more difficult to utilize outside of a laboratory environment. Still, some applications discussed in the workshop do take advantage of these 'quantum-enhanced' features. They build on the more established quantum technologies that are amenable to manipulation at the quantum level, such as atom magnetometers and atomic clocks. Understanding and developing those technologies through traditional engineering will clarify where quantum-enhanced features can be used most effectively, in addition to providing end users with improved devices in the near-term.

  17. 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.

  18. 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

  19. Making Weirdness Work: Quantum Information and Computation

    E-print Network

    Preskill, John

    Making Weirdness Work: Quantum Information and Computation John Preskill California Institute of in quantum physics. In fact, quantum information has weird properties that contrast sharply with the familiar

  20. Programming Pulse Driven Quantum Computers

    E-print Network

    Seth Lloyd

    1999-12-17

    Arrays of weakly-coupled quantum systems can be made to compute by subjecting them to a sequence of electromagnetic pulses of well-defined frequency and length. Such pulsed arrays are true quantum computers: bits can be placed in superpositions of 0 and 1, logical operations take place coherently, and dissipation is required only for error correction. Programming such computers is accomplished by selecting the proper sequence of pulses.

  1. Database Manipulation on Quantum Computers

    E-print Network

    Ahmed Younes

    2007-05-29

    Manipulating a database system on a quantum computer is an essential aim to benefit from the promising speed-up of quantum computers over classical computers in areas that take a vast amount of storage and processing time such as in databases. In this paper, the basic operations for manipulating the data in a quantum database will be defined, e.g. INSERT, UPDATE, DELETE, SELECT, backing up and restoring a database file. This gives the ability to perform the data processing that usually takes a long processing time on a classical database system, in a simultaneous way on a quantum computer. Defining a quantum version of more advanced concepts used in database systems, e.g. the referential integrity and the relational algebra, is a normal extension to this work

  2. Quantum Computing via The Bethe Ansatz

    E-print Network

    Yong Zhang

    2011-06-20

    We recognize quantum circuit model of computation as factorisable scattering model and propose that a quantum computer is associated with a quantum many-body system solved by the Bethe ansatz. As an typical example to support our perspectives on quantum computation, we study quantum computing in one-dimensional nonrelativistic system with delta-function interaction, where the two-body scattering matrix satisfies the factorisation equation (the quantum Yang--Baxter equation) and acts as a parametric two-body quantum gate. We conclude by comparing quantum computing via the factorisable scattering with topological quantum computing.

  3. Quantum Computation: Towards the Construction of a `Between Quantum and Classical Computer'

    E-print Network

    Aerts, Diederik

    the possibility to construct a `between quantum and classical' computer. In this view, the pure quantum computer computers [4, 5]. From a more theoretical and philosophical point of view quantum computing is alsoQuantum Computation: Towards the Construction of a `Between Quantum and Classical Computer

  4. Symmetrically private information retrieval based on blind quantum computing

    NASA Astrophysics Data System (ADS)

    Sun, Zhiwei; Yu, Jianping; Wang, Ping; Xu, Lingling

    2015-05-01

    Universal blind quantum computation (UBQC) is a new secure quantum computing protocol which allows a user Alice who does not have any sophisticated quantum technology to delegate her computing to a server Bob without leaking any privacy. Using the features of UBQC, we propose a protocol to achieve symmetrically private information retrieval, which allows a quantum limited Alice to query an item from Bob with a fully fledged quantum computer; meanwhile, the privacy of both parties is preserved. The security of our protocol is based on the assumption that malicious Alice has no quantum computer, which avoids the impossibility proof of Lo. For the honest Alice, she is almost classical and only requires minimal quantum resources to carry out the proposed protocol. Therefore, she does not need any expensive laboratory which can maintain the coherence of complicated quantum experimental setups.

  5. Blueprint for a microwave ion trap quantum computer

    E-print Network

    B. Lekitsch; S. Weidt; A. G. Fowler; K. Mlmer; S. J. Devitt; C. Wunderlich; W. K. Hensinger

    2015-08-10

    A universal quantum computer will have fundamental impact on a vast number of research fields and technologies. Therefore an increasingly large scientific and industrial community is working towards the realization of such a device. A large scale quantum computer is best constructed using a modular approach. We present the blueprint for an ion trap based scalable quantum computer module which makes it possible to create an arbitrarily large quantum computer architecture powered by long-wavelength radiation. This quantum computer module controls all operations as a stand-alone unit, is constructed using silicon microfabrication techniques and within reach of current technology. To perform the required quantum computations, the module makes use of long-wavelength-radiation quantum gate technology and relies only on a vacuum environment and global laser and microwave fields. To scale this microwave quantum computer architecture beyond one module we also present a new approach that makes use of ion transport between different modules, thereby allowing connections between arbitrarily many modules for a large scale architecture. A high-error-threshold surface error correction code making use of such module interactions can be implemented in the proposed architecture to execute fault-tolerant quantum logic operations. With only minor adjustments these modules are also suitable for alternative ion trap quantum computer architectures, such as schemes using photonic interconnects.

  6. VolterraCIRM International School Quantum computer and quantum information

    E-print Network

    Petz, Dénes

    Volterra­CIRM International School Quantum computer and quantum information Levico Terme, Italy Ricerca Matematica (CIRM), Istituto Trentino di Cultura The theory of quantum information and computing examples 3. general principles of quantum computation (q­bits, computational bases, gates, dis- crete

  7. Decoherence in quantum walks and quantum computers

    E-print Network

    Hines, Andrew P

    2007-01-01

    Decoherence is the major stumbling block in the realization of a large-scale quantum computer. Ingenious methods have been devised to overcome decoherence, but their success has been proven only for over-simplified models of system-environment interaction. Whether such methods will be reliable in the face of more realistic models is a fundamental open question. In this partly pedagogical article, we study two toy models of quantum information processing, using the language of \\emph{quantum walks}. Decoherence is incorporated in 3 ways - by coupling to a noisy `projective measurement' system, and by coupling to oscillator and spin baths.

  8. Quantum Entanglement and Quantum Computational Algorithms

    E-print Network

    Arvind

    2000-12-21

    The existence of entangled quantum states gives extra power to quantum computers over their classical counterparts. Quantum entanglement shows up qualitatively at the level of two qubits. We show that if no entanglement is envolved then whatever one can do with qubits can also be done with classical optical systems. We demonstrate that the one- and the two-bit Deutsch-Jozsa algorithm does not require entanglement and can be mapped onto a classical optical scheme. It is only for three and more input bits that the DJ algorithm requires the implementation of entangling transformations and in these cases it is impossible to implement this algorithm classically.

  9. Efficient distributed quantum computing

    E-print Network

    Beals, Robert

    We provide algorithms for efficiently moving and addressing quantum memory in parallel. These imply that the standard circuit model can be simulated with a low overhead by a more realistic model of a distributed quantum ...

  10. Quantum technologies with hybrid systems

    PubMed Central

    Kurizki, Gershon; Bertet, Patrice; Kubo, Yuimaru; Mlmer, Klaus; Petrosyan, David; Rabl, Peter; Schmiedmayer, Jrg

    2015-01-01

    An extensively pursued current direction of research in physics aims at the development of practical technologies that exploit the effects of quantum mechanics. As part of this ongoing effort, devices for quantum information processing, secure communication, and high-precision sensing are being implemented with diverse systems, ranging from photons, atoms, and spins to mesoscopic superconducting and nanomechanical structures. Their physical properties make some of these systems better suited than others for specific tasks; thus, photons are well suited for transmitting quantum information, weakly interacting spins can serve as long-lived quantum memories, and superconducting elements can rapidly process information encoded in their quantum states. A central goal of the envisaged quantum technologies is to develop devices that can simultaneously perform several of these tasks, namely, reliably store, process, and transmit quantum information. Hybrid quantum systems composed of different physical components with complementary functionalities may provide precisely such multitasking capabilities. This article reviews some of the driving theoretical ideas and first experimental realizations of hybrid quantum systems and the opportunities and challenges they present and offers a glance at the near- and long-term perspectives of this fascinating and rapidly expanding field. PMID:25737558

  11. Quantum technologies with hybrid systems.

    PubMed

    Kurizki, Gershon; Bertet, Patrice; Kubo, Yuimaru; Mlmer, Klaus; Petrosyan, David; Rabl, Peter; Schmiedmayer, Jrg

    2015-03-31

    An extensively pursued current direction of research in physics aims at the development of practical technologies that exploit the effects of quantum mechanics. As part of this ongoing effort, devices for quantum information processing, secure communication, and high-precision sensing are being implemented with diverse systems, ranging from photons, atoms, and spins to mesoscopic superconducting and nanomechanical structures. Their physical properties make some of these systems better suited than others for specific tasks; thus, photons are well suited for transmitting quantum information, weakly interacting spins can serve as long-lived quantum memories, and superconducting elements can rapidly process information encoded in their quantum states. A central goal of the envisaged quantum technologies is to develop devices that can simultaneously perform several of these tasks, namely, reliably store, process, and transmit quantum information. Hybrid quantum systems composed of different physical components with complementary functionalities may provide precisely such multitasking capabilities. This article reviews some of the driving theoretical ideas and first experimental realizations of hybrid quantum systems and the opportunities and challenges they present and offers a glance at the near- and long-term perspectives of this fascinating and rapidly expanding field. PMID:25737558

  12. Computational Power of Quantum Machines, Quantum Grammars and Feasible Computation

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, E. V.

    This paper studies the computational power of quantum computers to explore as to whether they can recognize properties which are in nondeterministic polynomial-time class (NP) and beyond. To study the computational power, we use the Feynman's path integral (FPI) formulation of quantum mechanics. From a computational point of view the Feynman's path integral computes a quantum dynamical analogue of the k-ary relation computed by an Alternating Turing machine (ATM) using AND-OR Parallelism. Hence, if we can find a suitable mapping function between an instance of a mathematical problem and the corresponding interference problem, using suitable potential functions for which FPI can be integrated exactly, the computational power of a quantum computer can be bounded to that of an alternating Turing machine that can solve problems in NP (e.g, factorization problem) and in polynomial space. Unfortunately, FPI is exactly integrable only for a few problems (e.g., the harmonic oscillator) involving quadratic potentials; otherwise, they may be only approximately computable or noncomputable. This means we cannot in general solve all quantum dynamical problems exactly except for those special cases of quadratic potentials, e.g., harmonic oscillator. Since there is a one to one correspondence between the quantum mechanical problems that can be analytically solved and the path integrals that can be exactly evaluated, we can say that the noncomputability of FPI implies quantum unsolvability. This is the analogue of classical unsolvability. The Feynman's path graph can be considered as a semantic parse graph for the quantum mechanical sentence. It provides a semantic valuation function of the terminal sentence based on probability amplitudes to disambiguate a given quantum description and obtain an interpretation in a linear time. In Feynman's path integral, the kernels are partially ordered over time (different alternate paths acting concurrently at the same time) and multiplied. The semantic valuation is computable only if the FPI is computable. Thus both the expressive power and complexity aspects quantum computing are mirrored by the exact and efficient integrability of FPI.

  13. Computing on Anonymous Quantum Network

    E-print Network

    Hirotada Kobayashi; Keiji Matsumoto; Seiichiro Tani

    2010-01-29

    This paper considers distributed computing on an anonymous quantum network, a network in which no party has a unique identifier and quantum communication and computation are available. It is proved that the leader election problem can exactly (i.e., without error in bounded time) be solved with at most the same complexity up to a constant factor as that of exactly computing symmetric functions (without intermediate measurements for a distributed and superposed input), if the number of parties is given to every party. A corollary of this result is a more efficient quantum leader election algorithm than existing ones: the new quantum algorithm runs in O(n) rounds with bit complexity O(mn^2), on an anonymous quantum network with n parties and m communication links. Another corollary is the first quantum algorithm that exactly computes any computable Boolean function with round complexity O(n) and with smaller bit complexity than that of existing classical algorithms in the worst case over all (computable) Boolean functions and network topologies. More generally, any n-qubit state can be shared with that complexity on an anonymous quantum network with n parties.

  14. QUANTUM COMPUTATION AND GROVER'S ALGORITHM AARON KRAHN

    E-print Network

    May, J. Peter

    QUANTUM COMPUTATION AND GROVER'S ALGORITHM AARON KRAHN Abstract. This paper provides an introduction to quantum computation by develop- ing the qubit, quantum gate, and quantum circuits. Three simple with standard quantum computational techniques. Finally, we provide a detailed proof of Grover's searching

  15. Quantum computation and hidden variables

    E-print Network

    V. V. Aristov; A. V. Nikulov

    2010-07-12

    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.

  16. Innovative quantum technologies for microgravity fundamental physics and biological research

    NASA Technical Reports Server (NTRS)

    Kierk, I. K.

    2002-01-01

    This paper presents a new technology program, within the fundamental physics, focusing on four quantum technology areas: quantum atomics, quantum optics, space superconductivity and quantum sensor technology, and quantum field based sensor and modeling technology.

  17. Innovative quantum technologies for microgravity fundamental physics and biological research

    NASA Technical Reports Server (NTRS)

    Kierk, I.; Israelsson, U.; Lee, M.

    2001-01-01

    This paper presents a new technology program, within the fundamental physics research program, focusing on four quantum technology areas: quantum atomics, quantum optics, space superconductivity and quantum sensor technology, and quantum fluid based sensor and modeling technology.

  18. 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.

  19. PERTURBATION APPROACH FOR QUANTUM COMPUTATION

    SciTech Connect

    G. P. BERMAN; D. I. KAMENEV; V. I. TSIFRINOVICH

    2001-04-01

    We discuss how to simulate errors in the implementation of simple quantum logic operations in a nuclear spin quantum computer with many qubits, using radio-frequency pulses. We verify our perturbation approach using the exact solutions for relatively small (L = 10) number of qubits.

  20. 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 infinite dimensional Laplacian acting on some class of Lvy white noise functionals / K. Sait -- Structure of linear processes / Si Si and Win Win Htay -- Group theory of dynamical maps / E. C. G. Sudarshan -- On quantum analysis, quantum transfer-matrix method, and effective information entropy / M. Suzuki -- Nonequilibrium steady states for a harmonic oscillator interacting with two bose fields-stochastic limit approach and C* algebraic approach / S. Tasaki and L. Accardi -- Control of decoherence with multipulse application / C. Uchiyama -- Quantum entanglement, purification, and linear-optics quantum gates with photonic qubits / P. Walther and A. Zeilinger -- On quantum mutual type measures and capacity / N. Watanabe.

  1. State complexity and quantum computation

    E-print Network

    Yu Cai; Huy Nguyen Le; Valerio Scarani

    2015-08-18

    The complexity of a quantum state may be closely related to the usefulness of the state for quantum computation. We discuss this link using the tree size of a multiqubit state, a complexity measure that has two noticeable (and, so far, unique) features: it is in principle computable, and non-trivial lower bounds can be obtained, hence identifying truly complex states. In this paper, we first review the definition of tree size, together with known results on the most complex three and four qubits states. Moving to the multiqubit case, we revisit a mathematical theorem for proving a lower bound on tree size that scales superpolynomially in the number of qubits. Next, states with superpolynomial tree size, the Immanant states, the Deutsch-Jozsa states, the Shor's states and the subgroup states, are described. We show that the universal resource state for measurement based quantum computation, the 2D-cluster state, has superpolynomial tree size. Moreover, we show how the complexity of subgroup states and the 2D cluster state can be verified efficiently. The question of how tree size is related to the speed up achieved in quantum computation is also addressed. We show that superpolynomial tree size of the resource state is essential for measurement based quantum computation. The necessary role of large tree size in the circuit model of quantum computation is still a conjecture; and we prove a weaker version of the conjecture.

  2. State complexity and quantum computation

    NASA Astrophysics Data System (ADS)

    Cai, Yu; Le, Huy Nguyen; Scarani, Valerio

    2015-10-01

    The complexity of a quantum state may be closely related to the usefulness of the state for quantum computation. We discuss this link using the tree size of a multiqubit state, a complexity measure that has two noticeable (and, so far, unique) features: it is in principle computable, and non-trivial lower bounds can be obtained, hence identifying truly complex states. In this paper, we first review the definition of tree size, together with known results on the most complex three and four qubits states. Moving to the multiqubit case, we revisit a mathematical theorem for proving a lower bound on tree size that scales superpolynomially in the number of qubits. Next, states with superpolynomial tree size, the Immanant states, the Deutsch-Jozsa states, the Shor's states and the subgroup states, are described. We show that the universal resource state for measurement based quantum computation, the 2D-cluster state, has superpolynomial tree size. Moreover, we show how the complexity of subgroup states and the 2D cluster state can be verified efficiently. The question of how tree size is related to the speed up achieved in quantum computation is also addressed. We show that superpolynomial tree size of the resource state is essential for measurement based quantum computation. The necessary role of large tree size in the circuit model of quantum computation is still a conjecture; and we prove a weaker version of the conjecture.

  3. Quantum Computing over Finite Fields

    E-print Network

    Roshan P. James; Gerardo Ortiz; Amr Sabry

    2011-01-19

    In recent work, Benjamin Schumacher and Michael~D. Westmoreland investigate a version of quantum mechanics which they call "modal quantum theory" but which we prefer to call "discrete quantum theory". This theory is obtained by instantiating the mathematical framework of Hilbert spaces with a finite field instead of the field of complex numbers. This instantiation collapses much the structure of actual quantum mechanics but retains several of its distinguishing characteristics including the notions of superposition, interference, and entanglement. Furthermore, discrete quantum theory excludes local hidden variable models, has a no-cloning theorem, and can express natural counterparts of quantum information protocols such as superdense coding and teleportation. Our first result is to distill a model of discrete quantum computing from this quantum theory. The model is expressed using a monadic metalanguage built on top of a universal reversible language for finite computations, and hence is directly implementable in a language like Haskell. In addition to superpositions and invertible linear maps, the model includes conventional programming constructs including pairs, sums, higher-order functions, and recursion. Our second result is to relate this programming model to relational programming, e.g., a pure version of Prolog over finite relations. Surprisingly discrete quantum computing is identical to conventional logic programming except for a small twist that is responsible for all the ``quantum-ness.'' The twist occurs when merging sets of answers computed by several alternatives: the answers are combined using an "exclusive" version of logical disjunction. In other words, the two branches of a choice junction exhibit an "interference" effect: an answer is produced from the junction if it occurs in one or the other branch but not both.

  4. Duality quantum computer and the efficient quantum simulations

    E-print Network

    Shi-Jie Wei; Gui-Lu Long

    2015-07-12

    In this paper, we firstly briefly review the duality quantum computer. Distinctly, the generalized quantum gates, the basic evolution operators in a duality quantum computer are no longer unitary, and they can be expressed in terms of linear combinations of unitary operators. All linear bounded operators can be realized in a duality quantum computer, and unitary operators are just the extreme points of the set of generalized quantum gates. A d-slits duality quantum computer can be realized in an ordinary quantum computer with an additional qudit using the duality quantum computing mode. Duality quantum computer provides flexibility and clear physical picture in designing quantum algorithms, serving as a useful bridge between quantum and classical algorithms. In this review, we will show that duality quantum computer can simulate quantum systems more efficiently than ordinary quantum computers by providing descriptions of the recent efficient quantum simulation algorithms of Childs et al [Quantum Information & Computation, 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.

  5. Quantum Chaos and Quantum Computers D. L. Shepelyansky*

    E-print Network

    Shepelyansky, Dima

    Quantum Chaos and Quantum Computers D. L. Shepelyansky* Laboratoire de Physique Quantique, UMR 5626: 03.67.Lx, 05.45.Mt, 24.10.Cn Abstract The standard generic quantum computer model is studied and residual inter-qubit couplings, is determined. This phenomenon appears in an isolated quantum computer

  6. Distributed Quantum Computation Architecture Using Semiconductor Nanophotonics

    E-print Network

    Rodney Van Meter; Thaddeus D. Ladd; Austin G. Fowler; Yoshihisa Yamamoto

    2009-09-17

    In a large-scale quantum computer, the cost of communications will dominate the performance and resource requirements, place many severe demands on the technology, and constrain the architecture. Unfortunately, fault-tolerant computers based entirely on photons with probabilistic gates, though equipped with "built-in" communication, have very large resource overheads; likewise, computers with reliable probabilistic gates between photons or quantum memories may lack sufficient communication resources in the presence of realistic optical losses. Here, we consider a compromise architecture, in which semiconductor spin qubits are coupled by bright laser pulses through nanophotonic waveguides and cavities using a combination of frequent probabilistic and sparse determinstic entanglement mechanisms. The large photonic resource requirements incurred by the use of probabilistic gates for quantum communication are mitigated in part by the potential high-speed operation of the semiconductor nanophotonic hardware. The system employs topological cluster-state quantum error correction for achieving fault-tolerance. Our results suggest that such an architecture/technology combination has the potential to scale to a system capable of attacking classically intractable computational problems.

  7. From transistor to trapped-ion computers for quantum chemistry

    E-print Network

    M. -H. Yung; J. Casanova; A. Mezzacapo; J. McClean; L. Lamata; A. Aspuru-Guzik; E. Solano

    2013-07-16

    Over the last few decades, quantum chemistry has progressed through the development of computational methods based on modern digital computers. However, these methods can hardly fulfill the exponentially-growing resource requirements when applied to large quantum systems. As pointed out by Feynman, this restriction is intrinsic to all computational models based on classical physics. Recently, the rapid advancement of trapped-ion technologies has opened new possibilities for quantum control and quantum simulations. Here, we present an efficient toolkit that exploits both the internal and motional degrees of freedom of trapped ions for solving problems in quantum chemistry, including molecular electronic structure, molecular dynamics, and vibronic coupling. We focus on applications that go beyond the capacity of classical computers, but may be realizable on state-of-the-art trapped-ion systems. These results allow us to envision a new paradigm of quantum chemistry that shifts from the current transistor to a near-future trapped-ion-based technology.

  8. Quantum Computing using Linear Optics

    E-print Network

    T. B. Pittman; B. C. Jacobs; J. D. Franson

    2004-06-25

    Quantum computers are expected to be able to solve mathematical problems that cannot be solved using conventional computers. Many of these problems are of practical importance, especially in the areas of cryptography and secure communications. APL is developing an optical approach to quantum computing in which the bits, or "qubits", are represented by single photons. Our approach allows the use of ordinary (linear) optical elements that are available for the most part as off-the-shelf components. Recent experimental demonstrations of a variety of logic gates for single photons, a prototype memory device, and other devices will be described.

  9. A Magnetic Resonance Force Microscopy Quantum Computer with Tellurium Donors in Silicon

    E-print Network

    G. P. Berman; G. D. Doolen; V. I. Tsifrinovich

    2000-03-18

    We propose a magnetic resonance force microscopy (MRFM)-based nuclear spin quantum computer using tellurium impurities in silicon. This approach to quantum computing combines the well-developed silicon technology with expected advances in MRFM.

  10. Phase Information in Quantum Oracle Computing

    E-print Network

    J. Machta

    1998-05-07

    Computational devices may be supplied with external sources of information (oracles). Quantum oracles may transmit phase information which is available to a quantum computer but not a classical computer. One consequence of this observation is that there is an oracle which is of no assistance to a classical computer but which allows a quantum computer to solve undecidable problems. Thus useful relativized separations between quantum and classical complexity classes must exclude the transmission of phase information from oracle to computer.

  11. Introduction to Quantum Computing Emma Strubell

    E-print Network

    Siegelmann , Hava T

    this property for cryptographic purposes Emma Strubell (University of Maine) Intro to Quantum Computing April 12Introduction to Quantum Computing Part I Emma Strubell http://cs.umaine.edu/~ema/quantum_tutorial.pdf April 12, 2011 #12;Outline Overview What is quantum computing? Background Caveats Mathematical

  12. Thoughts on Noise and Quantum Computation

    E-print Network

    Kalai, Gil

    of view. An early critique of quantum computation concerned the matter of noise which must exist-tolerant quantum algorithms and potentially to quantum computing in general. Our basic point of viewThoughts on Noise and Quantum Computation Gil Kalai Hebrew University of Jerusalem and Yale

  13. On the Problem of Programming Quantum Computers

    E-print Network

    Hans De Raedt; Anthony Hams; Kristel Michielsen; Seiji Miyashita; Keiji Saito

    2000-09-27

    We study effects of the physical realization of quantum computers on their logical operation. Through simulation of physical models of quantum computer hardware, we analyse the difficulties that are encountered in programming physical implementations of quantum computers. We discuss the origin of the instabilities of quantum algorithms and explore physical mechanisms to enlarge the region(s) of stable operation.

  14. Reliable quantum computers BY JOHN PRESKILL

    E-print Network

    Preskill, John

    Reliable quantum computers BY JOHN PRESKILL Charles C. Lauritsen Laboratory of High Energy Physics long quantum computation can be performed reliably, provided that the average probability of error per quantum gate is less than a certain critical value, the accuracy threshold. A quantum computer storing

  15. quantph/9802065 Basics of Quantum Computation

    E-print Network

    Crépeau, Claude

    quant­ph/9802065 25 Feb 1998 Basics of Quantum Computation Vlatko Vedral and Martin B. Plenio) Quantum computers require quantum logic, something fundamentally different to classical Boolean logic. This difference leads to a greater efficiency of quantum computation over its classical counter

  16. [Earth Science Technology Office's Computational Technologies Project

    NASA Technical Reports Server (NTRS)

    Fischer, James (Technical Monitor); Merkey, Phillip

    2005-01-01

    This grant supported the effort to characterize the problem domain of the Earth Science Technology Office's Computational Technologies Project, to engage the Beowulf Cluster Computing Community as well as the High Performance Computing Research Community so that we can predict the applicability of said technologies to the scientific community represented by the CT project and formulate long term strategies to provide the computational resources necessary to attain the anticipated scientific objectives of the CT project. Specifically, the goal of the evaluation effort is to use the information gathered over the course of the Round-3 investigations to quantify the trends in scientific expectations, the algorithmic requirements and capabilities of high-performance computers to satisfy this anticipated need.

  17. Universal Single-Server Blind Quantum Computation for Classical Client

    E-print Network

    Hai-Ru Xu; Bang-Hai Wang

    2014-11-12

    Blind quantum computation allows a client without enough quantum technologies to delegate her quantum computation to quantum server, while keeping her input, output and algorithm secure. In this paper, we propose a universal single-server and classical-client blind quantum computation protocol based on entanglement swapping technology. In our protocol, the client interface with only one server and the only ability of the client requires is to get particles from trusted center and forward them to the server. Moreover, the protocol can be modified to make client completely classical by improving the ability of the trusted center. Numbers of blind quantum computation protocols have been presented in recent years, including single-, double- and triple-server protocols. In the single-server protocol, client needs to prepare single qubits. Though client can be classical in the double-server protocol, the two servers, who share Bell state from trusted center, are not allowed to communicate with each other. Recently, the triple-server protocol solves the noncommunication problem. Three servers, however, make the implementation of the computation sophisticated and unrealistic. Since it is impossible for blind quantum computation with only classical client and single server, blind quantum computation may work in the "Cloud + E-commerce" style in the future. Our protocol might become a key ingredient for real-life application in the first generation of quantum computations.

  18. Quantum Computing with Very Noisy Devices

    E-print Network

    E. Knill

    2004-11-02

    In theory, quantum computers can efficiently simulate quantum physics, factor large numbers and estimate integrals, thus solving otherwise intractable computational problems. In practice, quantum computers must operate with noisy devices called ``gates'' that tend to destroy the fragile quantum states needed for computation. The goal of fault-tolerant quantum computing is to compute accurately even when gates have a high probability of error each time they are used. Here we give evidence that accurate quantum computing is possible with error probabilities above 3% per gate, which is significantly higher than what was previously thought possible. However, the resources required for computing at such high error probabilities are excessive. Fortunately, they decrease rapidly with decreasing error probabilities. If we had quantum resources comparable to the considerable resources available in today's digital computers, we could implement non-trivial quantum computations at error probabilities as high as 1% per gate.

  19. Quantum Computing in Plato's Cave

    E-print Network

    Daniel Burgarth; Paolo Facchi; Vittorio Giovannetti; Hiromichi Nakazato; Saverio Pascazio; Kazuya Yuasa

    2014-03-23

    We show that mere observation of a quantum system can turn its dynamics from a very simple one into a universal quantum computation. This effect, which occurs if the system is regularly observed at short time intervals, can be rephrased as a modern version of Plato's Cave allegory. More precisely, while in the original version of the myth, the reality perceived within the Cave is described by the projected shadows of some more fundamental dynamics which is intrinsically more complex, we found that in the quantum world the situation changes drastically as the "projected" reality perceived through sequences of measurements can be more complex than the one that originated it. After discussing examples we go on to show that this effect is generally to be expected: almost any quantum dynamics will become universal once "observed" as outlined above. Conversely, we show that any complex quantum dynamics can be "purified" into a simpler one in larger dimensions.

  20. Efficient quantum computing insensitive to phase errors

    E-print Network

    B. Georgeot; D. L. Shepelyansky

    2001-05-29

    We show that certain computational algorithms can be simulated on a quantum computer with exponential efficiency and be insensitive to phase errors. Our explicit algorithm simulates accurately the classical chaotic dynamics for exponentially many orbits even when the quantum fidelity drops to zero. Such phase-insensitive algorithms open new possibilities for computation on realistic quantum computers.

  1. Theory of Quantum Computing and Communication

    E-print Network

    Fortnow, Lance

    Theory of Quantum Computing and Communication A report from the NSF sponsored workshop held January of Computer-Communications Research (C- CR) develop a new initiative in "Theory of Quantum Computing applications? We believe that C-CR should establish a new initiative in the "Theory of Quantum Computation

  2. Programming physical realizations of quantum computers

    E-print Network

    Hans De Raedt; Kristel Michielsen; Anthony Hams; Seiji Miyashita; Keiji Saito

    2001-04-18

    We study effects of the physical realization of quantum computers on their logical operation. Through simulation of physical models of quantum computer hardware, we analyze the difficulties that are encountered in programming physical realizations of quantum computers. Examples of logically identical implementations of the controlled-NOT operation and Grover's database search algorithm are used to demonstrate that the results of a quantum computation are unstable with respect to the physical realization of the quantum computer. We discuss the origin of these instabilities and discuss possibilities to overcome this, for practical purposes, fundamental limitation of quantum computers.

  3. Computer Viruses. Technology Update.

    ERIC Educational Resources Information Center

    Ponder, Tim, Comp.; Ropog, Marty, Comp.; Keating, Joseph, Comp.

    This document provides general information on computer viruses, how to help protect a computer network from them, measures to take if a computer becomes infected. Highlights include the origins of computer viruses; virus contraction; a description of some common virus types (File Virus, Boot Sector/Partition Table Viruses, Trojan Horses, and

  4. Silicon-based Quantum Computing

    NASA Astrophysics Data System (ADS)

    Clark, Robert

    2002-03-01

    The Australian Centre for Quantum Computer Technology has as a central focus the construction of few-qubit silicon-based solid state devices for test, by a reliable, reproducable and potentially scalable fabrication route. A description will be given of the fabrication approaches underway, with progress to date. Three principal objectives are within reach: 1. The ability to dope silicon with phosphorus in an atomically-precise array, using STM-lithography and Si-MBE overgrowth. 2. The construction of few-donor QC devices using single-ion implantation through nanofabricated apertures, with on-chip detection, self-aligned control gates and single electron transistor (SET) readout devices. 3. A high frequency experiment, using rf-SETs, to measure the coherent electron transfer between two buried phosphorus donor atoms constituting a nanostructured H_2^+ molecule encapsulated in silicon. This work is being carried out in collaboration with Los Alamos National Laboratory and is funded by the Australian Research Council, the Australian Government, the US Army Research Office, National Security Agency and Advanced Research and Development Activity.

  5. Impossibility of secure cloud quantum computing for classical client

    E-print Network

    Tomoyuki Morimae; Takeshi Koshiba

    2014-07-07

    The first generation quantum computer will be implemented in the cloud style, since only few groups will be able to access such an expensive and high-maintenance machine. How the privacy of the client can be protected in such a cloud quantum computing? It was theoretically shown [A. Broadbent, J. F. Fitzsimons, and E. Kashefi, Proceedings of the 50th Annual IEEE Symposium on Foundation of Computer Science, 517 (2009)], and experimentally demonstrated [S. Barz, E. Kashefi, A. Broadbent, J. F. Fitzsimons, A. Zeilinger, and P. Walther, Science {\\bf335}, 303 (2012)] that a client who can generate randomly-rotated single qubit states can delegate her quantum computing to a remote quantum server without leaking any privacy. The generation of a single qubit state is not too much burden for the client, and therefore we can say that "almost classical client" can enjoy the secure cloud quantum computing. However, isn't is possible to realize a secure cloud quantum computing for a client who is completely free from any quantum technology? Here we show that perfectly-secure cloud quantum computing is impossible for a completely classical client unless classical computing can simulate quantum computing, or a breakthrough is brought in classical cryptography.

  6. Quantum computing of quantum chaos and imperfection effects

    E-print Network

    Pil Hun Song; Dima L. Shepelyansky

    2000-09-01

    We study numerically the imperfection effects in the quantum computing of the kicked rotator model in the regime of quantum chaos. It is shown that there are two types of physical characteristics: for one of them the quantum computation errors grow exponentially with the number of qubits in the computer while for the other the growth is polynomial. Certain similarity between classical and quantum computing errors is also discussed.

  7. Computers, Technology, and Disability. [Update.

    ERIC Educational Resources Information Center

    American Council on Education, Washington, DC. HEATH Resource Center.

    This paper describes programs and resources that focus on access of postsecondary students with disabilities to computers and other forms of technology. Increased access to technological devices and services is provided to students with disabilities under the Technology-Related Assistance for Individuals with Disabilities Act (Tech Act). Section

  8. Quantum Cryptographic Network based on Quantum Memories Computer Science Department

    E-print Network

    Biham, Eli

    Quantum Cryptographic Network based on Quantum Memories Eli Biham Computer Science Department transmission of information. We present a quantum cryptographic system, in which users store particles in the same center. Unlike other quantum cryptographic systems, it can work without quantum channels

  9. Holonomic Quantum Computation via Adiabatic Shortcut

    E-print Network

    J. Zhang; Thi Ha Kyaw; D. M. Tong; Erik Sjqvist; L. C. Kwek

    2014-12-09

    Fast quantum gates based on geometric phases provide a platform for performing robust quantum computation. In particular, non-adiabatic holonomic quantum computation, which involves non-Abelian geometric phases to achieve universality, has recently been demonstrated in several experiments. Here, we generalize the transitionless quantum driving algorithm to a degenerate Hilbert space, with which we propose a route towards fast holonomic quantum computation. We propose a proof-of-principle experiment in a superconducting circuit architecture to realize our scheme.

  10. Analogical Modeling and Quantum Computing

    E-print Network

    Royal Skousen

    2000-08-25

    This paper serves as a bridge between quantum computing and analogical modeling (a general theory for predicting categories of behavior in varying contexts). Since its formulation in the early 1980s, analogical modeling has been successfully applied to a variety of problems in language. Several striking similarities between quantum mechanics and analogical modeling have recently been noted: (1) traditional statistics can be derived from a non-statistical basis by assuming data occurrences are accessed through a spin-up state (given two equally probable quantum states, spin-up and spin-down); (2) the probability of predicting a particular outcome is determined by the squaring of an underlying linear measure and is the result of decoherence (which occurs when a quantum system is observed); and (3) a natural measure of certainty (called the agreement) is based on one chance of guessing the right outcome and corresponds to the integrated squaring of Schroedinger's wave equation. Analogical modeling considers all possible combiantions of a given context of n variables, which is classical terms leads to an exponential explosion on the order of 2**n. This paper proposes a quantum computational solution to this exponentiality by applying a cycle of reversible quantum operators to all 2**n possibilities, thus reducing the time and space of analogical modeling to a polynomial order.

  11. A Quantum Computer Architecture using Nonlocal Interactions

    E-print Network

    Gavin K. Brennen; Daegene Song; Carl J. Williams

    2003-04-23

    Several authors have described the basic requirements essential to build a scalable quantum computer. Because many physical implementation schemes for quantum computing rely on nearest neighbor interactions, there is a hidden quantum communication overhead to connect distant nodes of the computer. In this paper we propose a physical solution to this problem which, together with the key building blocks, provides a pathway to a scalable quantum architecture using nonlocal interactions. Our solution involves the concept of a quantum bus that acts as a refreshable entanglement resource to connect distant memory nodes providing an architectural concept for quantum computers analogous to the von Neumann architecture for classical computers.

  12. Universal Blind Quantum Computing with coherent states

    E-print Network

    Vallette, Bruno

    Universal Blind Quantum Computing with coherent states Anthony Leverrier (ICFO, Barcelona the near future... sure... but more importantly : Anthony Leverrier (ICFO, Barcelona) Blind Quantum Computing #12;In the near future... sure... but more importantly : Anthony Leverrier (ICFO, Barcelona) Blind

  13. AFSTUDEEROPDRACHT Versnellen van Computational Quantum Chemistry

    E-print Network

    Vuik, Kees

    AFSTUDEEROPDRACHT Versnellen van Computational Quantum Chemistry softwarepakket ADF m.b.v. GPU's Achtergrond Computational Chemistry houdt zich bezig met het voorspellen en begrijpen van chemische processen

  14. Experimental Demonstration of Blind Quantum Computing

    E-print Network

    Stefanie Barz; Elham Kashefi; Anne Broadbent; Joseph F. Fitzsimons; Anton Zeilinger; Philip Walther

    2011-10-06

    Quantum computers, besides offering substantial computational speedups, are also expected to provide the possibility of preserving the privacy of a computation. Here we show the first such experimental demonstration of blind quantum computation where the input, computation, and output all remain unknown to the computer. We exploit the conceptual framework of measurement-based quantum computation that enables a client to delegate a computation to a quantum server. We demonstrate various blind delegated computations, including one- and two-qubit gates and the Deutsch and Grover algorithms. Remarkably, the client only needs to be able to prepare and transmit individual photonic qubits. Our demonstration is crucial for future unconditionally secure quantum cloud computing and might become a key ingredient for real-life applications, especially when considering the challenges of making powerful quantum computers widely available.

  15. Is the Brain a Quantum Computer? Abninder Litta

    E-print Network

    Eliasmith, Chris

    to understand human thinking have historically drawn on analogies with contemporary technologies, fromIs the Brain a Quantum Computer? Abninder Litta , Chris Eliasmithb,c , Frederick W. Kroona , Steven via quantum mechanical processes is irrelevant to explaining how brains produce thought, contrary

  16. KLM quantum computation as a measurement based computation

    E-print Network

    Sandu Popescu

    2006-10-04

    We show that the Knill Laflamme Milburn method of quantum computation with linear optics gates can be interpreted as a one-way, measurement based quantum computation of the type introduced by Briegel and Rausendorf. We also show that the permanent state of n n-dimensional systems is a universal state for quantum computation.

  17. Categorical Quantum Computing with Finite Fields

    E-print Network

    Murawski, Andrzej

    Categorical Quantum Computing with Finite Fields Matthew Varughese candidate number 141034 theory in quantum computing. We cover the use of symmetric monoidal categories, diagrammatic calculi such a fascinating introduction to quantum computing in his lecture course, my choice to write a dissertation

  18. Physical implementations of quantum computing Andrew Daley

    E-print Network

    Griffiths, Robert B.

    Physical implementations of quantum computing Andrew Daley Department of Physics and Astronomy Implementation of Quantum Computation", Fortschritte der Physik 48, p. 771 (2000) arXiv:quant-ph/0002077 Requirements for the implementation of quantum computation 1. A scalable physical system with well

  19. January 18, 2007 Topological Quantum Computing

    E-print Network

    1 Date January 18, 2007 Title Topological Quantum Computing Speaker Chetan Nayak (Station Q) Abstract The computational power of a quantum-mechanical Hilbert space is potentially far greater than and Quantum Computation (CSQC) University of California, Santa Barbara, CA 93106-6105 Phone: 805

  20. Computationally binding quantum commitments Dominique Unruh

    E-print Network

    International Association for Cryptologic Research (IACR)

    Computationally binding quantum commitments Dominique Unruh University of Tartu April 21, 2015 Abstract. We present a new definition of computationally binding commitment schemes in the quantum setting of computationally binding string commitment schemes in the quantum setting. A commitment scheme is a two

  1. Computer Technology for Industry.

    ERIC Educational Resources Information Center

    Aviation/Space, 1982

    1982-01-01

    A special National Aeronautics and Space Administration (NASA) service is contributing to national productivity by providing industry with reusable, low-cost, government-developed computer programs. Located at the University of Georgia, NASA's Computer Software Management and Information Center (COSMIC) has developed programs for equipment

  2. Quantum Computing Using Crossed Atomic Beams

    E-print Network

    P. Blythe; B. Varcoe

    2006-05-23

    A quantum computer is a hypothetical device in which the laws of quantum mechanics are used to introduce a degree of parallelism into computations and which could therefore significantly improve on the computational speed of a classical computer at certain tasks. Cluster state quantum computing (recently proposed by Raussendorf and Briegel) is a new paradigm in quantum information processing and is a departure from the conventional model of quantum computation. The cluster state quantum computer begins by creating a highly entangled multi-particle state (the cluster state) which it uses as a quantum resource during the computation. Information is processed in the computer via selected measurements on individual qubits that form the cluster state. We describe in detail how a scalable quantum computer can be constructed using microwave cavity QED and, in a departure from the traditional understanding of a computer as a fixed array of computational elements, we show that cluster state quantum computing is well suited to atomic beam experiments. We show that all of the necessary elements have been individually realised, and that the construction of a truly scalable atomic beam quantum computer may be an experimental reality in the near future.

  3. Grating chips for quantum technologies

    NASA Astrophysics Data System (ADS)

    McGilligan, James Patrick; Ingleby, Stuart; Griffin, Paul Francis; Riis, Erling; Arnold, Aidan

    2015-05-01

    Laser cooled atomic samples have resulted in profound advances in frequency metrology, however the technology is typically complex and bulky. In the cover story of the May 2013 issue of Nature Nanotechnology we describe a micro-fabricated optical element that greatly facilitates miniaturisation of ultra-cold atom technology. Portable devices should be feasible with accuracy vastly exceeding that of equivalent room-temperature technology, with a minimal footprint. Laser cooled samples will be ideal for measurement devices e.g. portable atomic clocks and magnetometers and, moreover, they hold great potential for longer-term breakthroughs exploiting e.g. optical lattices for all-optical clocks and Bose-Einstein condensates for atom interferometry. Here we will discuss next generation diffractive optical elements (DOE) and demonstrate quantum based measurements on samples of ultra-cold atoms created using our miniaturised optical setup.

  4. Children and Computers: New Technology--

    E-print Network

    Cassell, Justine

    31 Children and Computers: New Technology-- Old Concerns Ellen A.Wartella Nancy Jennings Abstract concerns about the effect on children's development and well- being. Although we tend to see these issues. With the introduction of each of these technologies, proponents touted the educational benefits for children, while

  5. On optimising quantum communication in verifiable quantum computing

    E-print Network

    Theodoros Kapourniotis; Vedran Dunjko; Elham Kashefi

    2015-06-23

    In the absence of any efficient classical schemes for verifying a universal quantum computer, the importance of limiting the required quantum resources for this task has been highlighted recently. Currently, most of efficient quantum verification protocols are based on cryptographic techniques where an almost classical verifier executes her desired encrypted quantum computation remotely on an untrusted quantum prover. In this work we present a new protocol for quantum verification by incorporating existing techniques in a non-standard composition to reduce the required quantum communications between the verifier and the prover.

  6. A lambda calculus for quantum computation with classical control

    E-print Network

    Selinger, Peter

    A lambda calculus for quantum computation with classical control is to develop a functional programming language for quantum computers. We develop a lambda calculus a functional programming language for* * quan- tum computers. Quantum computing is a theory of computation

  7. Quantum Computation and Decision Trees

    E-print Network

    Edward Farhi; Sam Gutmann

    1998-03-20

    Many interesting computational problems can be reformulated in terms of decision trees. A natural classical algorithm is to then run a random walk on the tree, starting at the root, to see if the tree contains a node n levels from the root. We devise a quantum mechanical algorithm that evolves a state, initially localized at the root, through the tree. We prove that if the classical strategy succeeds in reaching level n in time polynomial in n, then so does the quantum algorithm. Moreover, we find examples of trees for which the classical algorithm requires time exponential in n, but for which the quantum algorithm succeeds in polynomial time. The examples we have so far, however, could also be solved in polynomial time by different classical algorithms.

  8. Exponential Gain in Quantum Computing of Quantum Chaos and Localization

    E-print Network

    B. Georgeot; D. L. Shepelyansky

    2001-03-26

    We present a quantum algorithm which simulates the quantum kicked rotator model exponentially faster than classical algorithms. This shows that important physical problems of quantum chaos, localization and Anderson transition can be modelled efficiently on a quantum computer. We also show that a similar algorithm simulates efficiently classical chaos in certain area-preserving maps.

  9. What quantum computers may tell us about quantum mechanics

    E-print Network

    Monroe, Christopher

    17 What quantum computers may tell us about quantum mechanics Christopher R. Monroe University of Michigan, Ann Arbor Quantum mechanics occupies a unique position in the history of science. It has sur successes of quantum mechanics, its foundations are often questioned, owing to the glaring difficulties

  10. Bifurcation-based adiabatic quantum computation with a nonlinear oscillator network: Toward quantum soft computing

    E-print Network

    Hayato Goto

    2015-12-28

    The dynamics of nonlinear systems qualitatively change depending on their parameters, which is called bifurcation. A quantum-mechanical nonlinear oscillator can yield a quantum superposition of two oscillation states, known as a Schr\\"odinger cat state, via quantum adiabatic evolution through its bifurcation point. Here we propose a quantum computer comprising such quantum nonlinear oscillators, instead of quantum bits, to solve hard combinatorial optimization problems. The nonlinear oscillator network finds optimal solutions via quantum adiabatic evolution, where nonlinear terms are increased slowly, in contrast to conventional adiabatic quantum computation or quantum annealing, where quantum fluctuation terms are decreased slowly. As a result of numerical simulations, it is concluded that quantum superposition and quantum fluctuation work effectively to find optimal solutions. It is also notable that the present computer is analogous to neural computers, which are also networks of nonlinear components. Thus, the present scheme will open new possibilities for quantum computation, nonlinear science, and artificial intelligence.

  11. 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

  12. Geometry of Discrete Quantum Computing

    E-print Network

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

    2013-05-16

    Conventional quantum computing entails a geometry based on the description of an n-qubit state using 2^{n} 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 Fp^2 (based on primes p congruent to 3 mod{4}) 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 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 DCP{2^{n}-1}, the discrete analog 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 Fp^2 have p^{n} (p-1)^{n} unentangled states (the product of the tally for a single qubit) with purity 1, and they have p^{n+1}(p-1)(p+1)^{n-1} maximally entangled states with purity zero.

  13. Experimental One-Way Quantum Computing

    E-print Network

    P. Walther; K. J. Resch; T. Rudolph; E. Schenck; H. Weinfurter; V. Vedral; M. Aspelmeyer; A. Zeilinger

    2005-03-14

    Standard quantum computation is based on sequences of unitary quantum logic gates which process qubits. The one-way quantum computer proposed by Raussendorf and Briegel is entirely different. It has changed our understanding of the requirements for quantum computation and more generally how we think about quantum physics. This new model requires qubits to be initialized in a highly-entangled cluster state. From this point, the quantum computation proceeds by a sequence of single-qubit measurements with classical feedforward of their outcomes. Because of the essential role of measurement a one-way quantum computer is irreversible. In the one-way quantum computer the order and choices of measurements determine the algorithm computed. We have experimentally realized four-qubit cluster states encoded into the polarization state of four photons. We fully characterize the quantum state by implementing the first experimental four-qubit quantum state tomography. Using this cluster state we demonstrate the feasibility of one-way quantum computing through a universal set of one- and two-qubit operations. Finally, our implementation of Grover's search algorithm demonstrates that one-way quantum computation is ideally suited for such tasks.

  14. 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.

  15. Computer Technology for Industry

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Shell Oil Company used a COSMIC program, called VISCEL to insure the accuracy of the company's new computer code for analyzing polymers, and chemical compounds. Shell reported that there were no other programs available that could provide the necessary calculations. Shell produces chemicals for plastic products used in the manufacture of automobiles, housewares, appliances, film, textiles, electronic equipment and furniture.

  16. 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

  17. Trusted Computing Technologies, Intel Trusted Execution Technology.

    SciTech Connect

    Guise, Max Joseph; Wendt, Jeremy Daniel

    2011-01-01

    We describe the current state-of-the-art in Trusted Computing Technologies - focusing mainly on Intel's Trusted Execution Technology (TXT). This document is based on existing documentation and tests of two existing TXT-based systems: Intel's Trusted Boot and Invisible Things Lab's Qubes OS. We describe what features are lacking in current implementations, describe what a mature system could provide, and present a list of developments to watch. Critical systems perform operation-critical computations on high importance data. In such systems, the inputs, computation steps, and outputs may be highly sensitive. Sensitive components must be protected from both unauthorized release, and unauthorized alteration: Unauthorized users should not access the sensitive input and sensitive output data, nor be able to alter them; the computation contains intermediate data with the same requirements, and executes algorithms that the unauthorized should not be able to know or alter. Due to various system requirements, such critical systems are frequently built from commercial hardware, employ commercial software, and require network access. These hardware, software, and network system components increase the risk that sensitive input data, computation, and output data may be compromised.

  18. 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

  19. Quantum Computation Beyond the Circuit Model

    E-print Network

    Stephen P. Jordan

    2008-09-13

    The quantum circuit model is the most widely used model of quantum computation. It provides both a framework for formulating quantum algorithms and an architecture for the physical construction of quantum computers. However, several other models of quantum computation exist which provide useful alternative frameworks for both discovering new quantum algorithms and devising new physical implementations of quantum computers. In this thesis, I first present necessary background material for a general physics audience and discuss existing models of quantum computation. Then, I present three results relating to various models of quantum computation: a scheme for improving the intrinsic fault tolerance of adiabatic quantum computers using quantum error detecting codes, a proof that a certain problem of estimating Jones polynomials is complete for the one clean qubit complexity class, and a generalization of perturbative gadgets which allows k-body interactions to be directly simulated using 2-body interactions. Lastly, I discuss general principles regarding quantum computation that I learned in the course of my research, and using these principles I propose directions for future research.

  20. Suppression of quantum chaos in a quantum computer hardware.

    PubMed

    Lages, J; Shepelyansky, D L

    2006-08-01

    We present numerical and analytical studies of a quantum computer proposed by the Yamamoto group in Phys. Rev. Lett. 89, 017901 (2002). The stable and quantum chaos regimes in the quantum computer hardware are identified as a function of magnetic field gradient and dipole-dipole couplings between qubits on a square lattice. It is shown that a strong magnetic field gradient leads to suppression of quantum chaos. PMID:17025526

  1. Quantum Computation Beyond the "Standard Circuit Model"

    E-print Network

    K. Ch. Chatzisavvas; C. Daskaloyannis; C. P. Panos

    2006-08-16

    Construction of explicit quantum circuits follows the notion of the "standard circuit model" introduced in the solid and profound analysis of elementary gates providing quantum computation. Nevertheless the model is not always optimal (e.g. concerning the number of computational steps) and it neglects physical systems which cannot follow the "standard circuit model" analysis. We propose a computational scheme which overcomes the notion of the transposition from classical circuits providing a computation scheme with the least possible number of Hamiltonians in order to minimize the physical resources needed to perform quantum computation and to succeed a minimization of the computational procedure (minimizing the number of computational steps needed to perform an arbitrary unitary transformation). It is a general scheme of construction, independent of the specific system used for the implementation of the quantum computer. The open problem of controllability in Lie groups is directly related and rises to prominence in an effort to perform universal quantum computation.

  2. Review: Towards Spintronic Quantum Technologies with Dopants in Silicon

    E-print Network

    Gavin W. Morley

    2014-08-06

    Dopants in crystalline silicon such as phosphorus (Si:P) have electronic and nuclear spins with exceptionally long coherence times making them promising platforms for quantum computing and quantum sensing. The demonstration of single-spin single-shot readout brings these ideas closer to implementation. Progress in fabricating atomic-scale Si:P structures with scanning tunnelling microscopes offers a powerful route to scale up this work, taking advantage of techniques developed by the computing industry. The experimental and theoretical sides of this emerging quantum technology are reviewed with a focus on the period from 2009 to mid-2014.

  3. 987DNA, QUANTUM, AND MOLECULAR COMPUTING 988 DNA, QUANTUM, AND MOLECULAR COMPUTING

    E-print Network

    Fernandez, Thomas

    987DNA, QUANTUM, AND MOLECULAR COMPUTING #12;988 DNA, QUANTUM, AND MOLECULAR COMPUTING #12;DNA Fayetteville, AR 72701 rdeaton@uark.edu 501-575-5590 Abstract Both DNA and quantum computers have the potential than classical Turing machines. DNA computers are evolvable through biotechnol- ogy techniques

  4. 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.

  5. 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.

  6. 842 IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 21, NO. 13, JULY 1, 2009 Photonic Quantum Dual-Containing LDPC

    E-print Network

    Djordjevic, Ivan B.

    computing, quantum memories, quantum key distribution (QKD), quantum metrology, quantum lithography842 IEEE PHOTONICS TECHNOLOGY LETTERS, VOL. 21, NO. 13, JULY 1, 2009 Photonic Quantum Dual architectures for quantum low-density parity-check (LDPC) codes suitable for all-optical implementation, based

  7. Using Quantum Computers to Learn Physics

    E-print Network

    Nathan Wiebe

    2014-01-18

    Since its inception at the beginning of the twentieth century, quantum mechanics has challenged our conceptions of how the universe ought to work; however, the equations of quantum mechanics can be too computationally difficult to solve using existing computers for even modestly large systems. Here I will show that quantum computers can sometimes be used to address such problems and that quantum computer science can assign formal complexities to learning facts about nature. Hence, computer science should not only be regarded as an applied science; it is also of central importance to the foundations of science.

  8. The universal quantum driving force to speed up a quantum computation -- The unitary quantum dynamics

    E-print Network

    Xijia Miao

    2011-11-22

    It is shown in the paper that the unitary quantum dynamics in quantum mechanics is the universal quantum driving force to speed up a quantum computation. This assertion supports strongly in theory that the unitary quantum dynamics is the fundamental and universal principle in nature. On the other hand, the symmetric structure of Hilbert space of a composite quantum system is the quantum-computing resource that is not owned by classical computation. A new quantum-computing speedup theory is set up on the basis of the unitary quantum dynamics. Both the unitary quantum dynamics and the symmetric structure and property of the Hilbert space of the quantum system are mainly responsible for an exponential quantum-computing speedup for a general efficient quantum algorithm. The inherent importance for the unitary quantum dynamics to speed up a quantum computation lies in the unique ability of the unitary quantum dynamics to build the effective interaction between the symmetric structure of the Hilbert space of the quantum system and the mathematical symmetric structure of a problem to be solved on the quantum system. This unique ability could result in an essential difference of computational power between quantum and classical computations by combining the symmetric structure and property of the Hilbert space. The new quantum-computing speedup theory also provides reasonable mechanisms for exponential quantum-computing speedup for the existing efficient quantum algorithms based on the quantum parallel principle. These existing quantum algorithms including the hidden-subgroup-problem quantum algorithms and conventional quantum search algorithms have the common character that the symmetric structure of the Hilbert space does not have any effective effect on these quantum algorithms. This could be the main reason why these quantum algorithms are quite special and considered to be semiclassical.

  9. Physics and computer science: quantum computation and other approaches

    E-print Network

    Salvador E. Venegas-Andraca

    2011-03-07

    This is a position paper written as an introduction to the special volume on quantum algorithms I edited for the journal Mathematical Structures in Computer Science (Volume 20 - Special Issue 06 (Quantum Algorithms), 2010).

  10. 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.

  11. Quantum computing with superconductors I: Architectures

    E-print Network

    Michael R. Geller; Emily J. Pritchett; Andrew T. Sornborger; F. K. Wilhelm

    2006-03-24

    Josephson junctions have demonstrated enormous potential as qubits for scalable quantum computing architectures. Here we discuss the current approaches for making multi-qubit circuits and performing quantum information processing with them.

  12. Relativistic Quantum Metrology: Exploiting relativity to improve quantum measurement technologies

    E-print Network

    Mehdi Ahmadi; David Edward Bruschi; Carlos Sabn; Gerardo Adesso; Ivette Fuentes

    2014-04-29

    We present a framework for relativistic quantum metrology that is useful for both Earth-based and space-based technologies. Quantum metrology has been so far successfully applied to design precision instruments such as clocks and sensors which outperform classical devices by exploiting quantum properties. There are advanced plans to implement these and other quantum technologies in space, for instance Space-QUEST and Space Optical Clock projects intend to implement quantum communications and quantum clocks at regimes where relativity starts to kick in. However, typical setups do not take into account the effects of relativity on quantum properties. To include and exploit these effects, we introduce techniques for the application of metrology to quantum field theory. Quantum field theory properly incorporates quantum theory and relativity, in particular, at regimes where space-based experiments take place. This framework allows for high precision estimation of parameters that appear in quantum field theory including proper times and accelerations. Indeed, the techniques can be applied to develop a novel generation of relativistic quantum technologies for gravimeters, clocks and sensors. As an example, we present a high precision device which in principle improves the state-of-the-art in quantum accelerometers by exploiting relativistic effects.

  13. Relativistic quantum metrology: exploiting relativity to improve quantum measurement technologies.

    PubMed

    Ahmadi, Mehdi; Bruschi, David Edward; Sabn, Carlos; Adesso, Gerardo; Fuentes, Ivette

    2014-01-01

    We present a framework for relativistic quantum metrology that is useful for both Earth-based and space-based technologies. Quantum metrology has been so far successfully applied to design precision instruments such as clocks and sensors which outperform classical devices by exploiting quantum properties. There are advanced plans to implement these and other quantum technologies in space, for instance Space-QUEST and Space Optical Clock projects intend to implement quantum communications and quantum clocks at regimes where relativity starts to kick in. However, typical setups do not take into account the effects of relativity on quantum properties. To include and exploit these effects, we introduce techniques for the application of metrology to quantum field theory. Quantum field theory properly incorporates quantum theory and relativity, in particular, at regimes where space-based experiments take place. This framework allows for high precision estimation of parameters that appear in quantum field theory including proper times and accelerations. Indeed, the techniques can be applied to develop a novel generation of relativistic quantum technologies for gravimeters, clocks and sensors. As an example, we present a high precision device which in principle improves the state-of-the-art in quantum accelerometers by exploiting relativistic effects. PMID:24851858

  14. Relativistic Quantum Metrology: Exploiting relativity to improve quantum measurement technologies

    PubMed Central

    Ahmadi, Mehdi; Bruschi, David Edward; Sabn, Carlos; Adesso, Gerardo; Fuentes, Ivette

    2014-01-01

    We present a framework for relativistic quantum metrology that is useful for both Earth-based and space-based technologies. Quantum metrology has been so far successfully applied to design precision instruments such as clocks and sensors which outperform classical devices by exploiting quantum properties. There are advanced plans to implement these and other quantum technologies in space, for instance Space-QUEST and Space Optical Clock projects intend to implement quantum communications and quantum clocks at regimes where relativity starts to kick in. However, typical setups do not take into account the effects of relativity on quantum properties. To include and exploit these effects, we introduce techniques for the application of metrology to quantum field theory. Quantum field theory properly incorporates quantum theory and relativity, in particular, at regimes where space-based experiments take place. This framework allows for high precision estimation of parameters that appear in quantum field theory including proper times and accelerations. Indeed, the techniques can be applied to develop a novel generation of relativistic quantum technologies for gravimeters, clocks and sensors. As an example, we present a high precision device which in principle improves the state-of-the-art in quantum accelerometers by exploiting relativistic effects. PMID:24851858

  15. Computed tomography: A versatile technology

    SciTech Connect

    Armistead, R.A.; Stanley, J.H.

    1997-02-01

    Improvements in the speed and accuracy of computed tomography (CT) systems, together with new developments in software, are changing the ways CT technology supports manufacturing operations. In addition to providing quantitative nondestructive inspection at the end of the manufacturing line, CT images are now also being compiled for reverse engineering and first-article characterization and certification. The enhanced performance of a state-of-the-art CT system makes it an effective complement to other digital data-based manufacturing technologies such as computer-aided design (CAD), computer-aided manufacturing (CAM), and computer-aided engineering (CAE). Furthermore, CT capabilities may be combined with those of rapid prototyping such as stereolithography, selective laser sintering, and direct metal deposition, to support the rapid, cost-efficient production of parts in small lots. This article describes how the system works, how it is used for inspection, and how it may assist with reverse engineering.

  16. 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

  17. Mini-maximizing two qubit quantum computations

    E-print Network

    Faisal Shah Khan; Simon J. D. Phoenix

    2013-09-10

    Two qubit quantum computations are viewed as two player, strictly competitive games and a game-theoretic measure of optimality of these computations is developed. To this end, the geometry of Hilbert space of quantum computations is used to establish the equivalence of game-theoretic solution concepts of Nash equilibrium and mini-max outcomes in games of this type, and quantum mechanisms are designed for realizing these mini-max outcomes.

  18. Gate-teleportation-based blind quantum computation

    E-print Network

    Mear M. R. Koochakie

    2014-12-25

    Blind quantum computation (BQC) is a model in which a computation is performed on a server by a client such that the server is kept blind about the input, the algorithm, and the output of the computation. Here we layout a general framework for BQC which, unlike the previous BQC models, does not constructed on specific computational model. A main ingredient of our construction is gate teleportation. We demonstrate that our framework can be straightforwardly implemented on circuit-based models as well as measurement-based models of quantum computation. We illustrate our construction by showing that universal BQC is possible on correlation-space measurement-based quantum computation models.

  19. Accounting Principles are Simulated on Quantum Computers

    E-print Network

    Do Ngoc Diep; Do Hoang Giang

    2007-07-04

    The paper is devoted to a new idea of simulation of accounting by quantum computing. We expose the actual accounting principles in a pure mathematics language. After that we simulated the accounting principles on quantum computers. We show that all arbitrary accounting actions are exhausted by the described basic actions. The main problem of accounting are reduced to some system of linear equations in the economic model of Leontief. In this simulation we use our constructed quantum Gau\\ss-Jordan Elimination to solve the problem and the time of quantum computing is some square root order faster than the time in classical computing.

  20. 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.

  1. 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).

  2. the quantum Quantum estimation for

    E-print Network

    Vallette, Bruno

    (communication and computing) Quantum metrology (calibration, interferometry, nanopositioning) Quantum imaging-enahnced metrology/technology are entanglement, nonlocality, entropy, interferometric phase-shift, etc.. #12;Quantum estimation The "resources" involved in quantum-enahnced metrology/technology are entanglement, nonlocality

  3. Optical Computers and Space Technology

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin A.; Frazier, Donald O.; Penn, Benjamin; Paley, Mark S.; Witherow, William K.; Banks, Curtis; Hicks, Rosilen; Shields, Angela

    1995-01-01

    The rapidly increasing demand for greater speed and efficiency on the information superhighway requires significant improvements over conventional electronic logic circuits. Optical interconnections and optical integrated circuits are strong candidates to provide the way out of the extreme limitations imposed on the growth of speed and complexity of nowadays computations by the conventional electronic logic circuits. The new optical technology has increased the demand for high quality optical materials. NASA's recent involvement in processing optical materials in space has demonstrated that a new and unique class of high quality optical materials are processible in a microgravity environment. Microgravity processing can induce improved orders in these materials and could have a significant impact on the development of optical computers. We will discuss NASA's role in processing these materials and report on some of the associated nonlinear optical properties which are quite useful for optical computers technology.

  4. Computing quantum discord is NP-complete

    E-print Network

    Yichen Huang

    2014-03-28

    We study the computational complexity of quantum discord (a measure of quantum correlation beyond entanglement), and prove that computing quantum discord is NP-complete. Therefore, quantum discord is computationally intractable: the running time of any algorithm for computing quantum discord is believed to grow exponentially with the dimension of the Hilbert space so that computing quantum discord in a quantum system of moderate size is not possible in practice. As by-products, some entanglement measures (namely entanglement cost, entanglement of formation, relative entropy of entanglement, squashed entanglement, classical squashed entanglement, conditional entanglement of mutual information, and broadcast regularization of mutual information) and constrained Holevo capacity are NP-hard/NP-complete to compute. These complexity-theoretic results are directly applicable in common randomness distillation, quantum state merging, entanglement distillation, superdense coding, and quantum teleportation; they may offer significant insights into quantum information processing. Moreover, we prove the NP-completeness of two typical problems: linear optimization over classical states and detecting classical states in a convex set, providing evidence that working with classical states is generically computationally intractable.

  5. 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.

  6. Building logical qubits in a superconducting quantum computing system

    E-print Network

    Jay M. Gambetta; Jerry M. Chow; Matthias Steffen

    2015-10-15

    The technological world is in the midst of a quantum computing and quantum information revolution. Since Richard Feynman's famous "plenty of room at the bottom" lecture, hinting at the notion of novel devices employing quantum mechanics, the quantum information community has taken gigantic strides in understanding the potential applications of a quantum computer and laid the foundational requirements for building one. We believe that the next significant step will be to demonstrate a quantum memory, in which a system of interacting qubits stores an encoded logical qubit state longer than the incorporated parts. Here, we describe the important route towards a logical memory with superconducting qubits, employing a rotated version of the surface code. The current status of technology with regards to interconnected superconducting-qubit networks will be described and near-term areas of focus to improve devices will be identified. Overall, the progress in this exciting field has been astounding, but we are at an important turning point where it will be critical to incorporate engineering solutions with quantum architectural considerations, laying the foundation towards scalable fault-tolerant quantum computers in the near future.

  7. Quantum computation speedup limits from quantum metrological precision bounds

    NASA Astrophysics Data System (ADS)

    Demkowicz-Dobrza?ski, Rafa?; Markiewicz, Marcin

    2015-06-01

    We propose a scheme for translating metrological precision bounds into lower bounds on query complexity of quantum search algorithms. Within the scheme the link between quadratic performance enhancement in idealized quantum metrological and quantum computing schemes becomes clear. More importantly, we utilize results from the field of quantum metrology on a generic loss of quadratic quantum precision enhancement in the presence of decoherence to infer an analogous generic loss of quadratic speedup in oracle based quantum computing. While most of our reasoning is rigorous, at one of the final steps, we need to make use of an unproven technical conjecture. We hope that we will be able to amend this deficiency in the near future, but we are convinced that even without the conjecture proven our results provide a deep insight into the relationship between quantum algorithms and quantum metrology protocols.

  8. Quantum computation speedup limits from quantum metrological precision bounds

    E-print Network

    Rafal Demkowicz-Dobrzanski; Marcin Markiewicz

    2015-06-17

    We propose a scheme for translating metrological precision bounds into lower bounds on query complexity of quantum search algorithms. Within the scheme the link between quadratic performance enhancement in idealized quantum metrological and quantum computing schemes becomes clear. More importantly, we utilize results from the field of quantum metrology on a generic loss of quadratic quantum precision enhancement in presence of decoherence to infer an analogous generic loss of quadratic speed-up in oracle based quantum computing. While most of our reasoning is rigorous, at one of the final steps, we need to make use of an unproven technical conjecture. We hope that we will be able to amend this deficiency in the near future, but we are convinced that even without the conjecture proven our results provide a novel and deep insight into relationship between quantum algorithms and quantum metrology protocols.

  9. PREFACE: Quantum Information, Communication, Computation and Cryptography

    NASA Astrophysics Data System (ADS)

    Benatti, F.; Fannes, M.; Floreanini, R.; Petritis, D.

    2007-07-01

    The application of quantum mechanics to information related fields such as communication, computation and cryptography is a fast growing line of research that has been witnessing an outburst of theoretical and experimental results, with possible practical applications. On the one hand, quantum cryptography with its impact on secrecy of transmission is having its first important actual implementations; on the other hand, the recent advances in quantum optics, ion trapping, BEC manipulation, spin and quantum dot technologies allow us to put to direct test a great deal of theoretical ideas and results. These achievements have stimulated a reborn interest in various aspects of quantum mechanics, creating a unique interplay between physics, both theoretical and experimental, mathematics, information theory and computer science. In view of all these developments, it appeared timely to organize a meeting where graduate students and young researchers could be exposed to the fundamentals of the theory, while senior experts could exchange their latest results. The activity was structured as a school followed by a workshop, and took place at The Abdus Salam International Center for Theoretical Physics (ICTP) and The International School for Advanced Studies (SISSA) in Trieste, Italy, from 12-23 June 2006. The meeting was part of the activity of the Joint European Master Curriculum Development Programme in Quantum Information, Communication, Cryptography and Computation, involving the Universities of Cergy-Pontoise (France), Chania (Greece), Leuven (Belgium), Rennes1 (France) and Trieste (Italy). This special issue of Journal of Physics A: Mathematical and Theoretical collects 22 contributions from well known experts who took part in the workshop. They summarize the present day status of the research in the manifold aspects of quantum information. The issue is opened by two review articles, the first by G Adesso and F Illuminati discussing entanglement in continuous variable systems, the second by T Prosen, discussing chaos and complexity in quantum systems. Both topics have theoretical as well as experimental relevance and are likely to witness a fast growing development in the near future. The remaining contributions present more specific and very recent results. They involve the study of the structure of quantum states and their estimation (B Baumgartner et al, C King et al, S Olivares et al, D Petz et al and W van Dam et al), of entanglement generation and its quantification (G Brida et al, F Ciccarello et al, G Costantini et al, O Romero-Isart et al, D Rossini et al, A Serafini et al and D Vitali et al), of randomness related effects on entanglement behaviour (I Akhalwaya et al, O Dahlsten et al and L Viola et al), and of abstract and applied aspects of quantum computation and communication (K Audenart, G M D'Ariano et al, N Datta et al, L C Kwek et al and M Nathanson et al). We would like to express our gratitude to the European Commission, the Abdus Salam ICTP, SISSA and Eurotech SpA (Amaro, Udine, Italy) for financial and/or logistic support. Special thanks also go to the workshop secretary Marina De Comelli, and the secretaries of the Department of Theoretical Physics, University of Trieste, Sabrina Gaspardis and Rosita Glavina for their precious help and assistance.

  10. Experimental realization of quantum games on a quantum computer.

    PubMed

    Du, Jiangfeng; Li, Hui; Xu, Xiaodong; Shi, Mingjun; Wu, Jihui; Zhou, Xianyi; Han, Rongdian

    2002-04-01

    We generalize the quantum prisoner's dilemma to the case where the players share a nonmaximally entangled states. We show that the game exhibits an intriguing structure as a function of the amount of entanglement with two thresholds which separate a classical region, an intermediate region, and a fully quantum region. Furthermore this quantum game is experimentally realized on our nuclear magnetic resonance quantum computer. PMID:11955126

  11. Computational quantum chemistry and adaptive ligand modeling in mechanistic QSAR.

    PubMed

    De Benedetti, Pier G; Fanelli, Francesca

    2010-10-01

    Drugs are adaptive molecules. They realize this peculiarity by generating different ensembles of prototropic forms and conformers that depend on the environment. Among the impressive amount of available computational drug discovery technologies, quantitative structure-activity relationship approaches that rely on computational quantum chemistry descriptors are the most appropriate to model adaptive drugs. Indeed, computational quantum chemistry descriptors are able to account for the variation of the intramolecular interactions of the training compounds, which reflect their adaptive intermolecular interaction propensities. This enables the development of causative, interpretive and reasonably predictive quantitative structure-activity relationship models, and, hence, sound chemical information finalized to drug design and discovery. PMID:20709183

  12. Communication Links for Distributed Quantum Computation

    E-print Network

    Rodney Van Meter; Kae Nemoto; W. J. Munro

    2007-01-09

    Distributed quantum computation requires quantum operations that act over a distance on error-correction encoded states of logical qubits, such as the transfer of qubits via teleportation. We evaluate the performance of several quantum error correction codes, and find that teleportation failure rates of one percent or more are tolerable when two levels of the [[23,1,7

  13. Quantum computers T. D. Ladd1

    E-print Network

    Monroe, Christopher

    by the laws of physics. It also allows quantum metrology, in which distance and time could be measuredREVIEWS Quantum computers T. D. Ladd1 {, F. Jelezko2 , R. Laflamme3,4,5 , Y. Nakamura6,7 , C. Monroe8,9 & J. L. O'Brien10 Over the past several decades, quantum information science has emerged

  14. 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

  15. Center for Advanced Computational Technology

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.

    2000-01-01

    The Center for Advanced Computational Technology (ACT) was established to serve as a focal point for diverse research activities pertaining to application of advanced computational technology to future aerospace systems. These activities include the use of numerical simulations, artificial intelligence methods, multimedia and synthetic environments, and computational intelligence, in the modeling, analysis, sensitivity studies, optimization, design and operation of future aerospace systems. The Center is located at NASA Langley and is an integral part of the School of Engineering and Applied Science of the University of Virginia. The Center has four specific objectives: 1) conduct innovative research on applications of advanced computational technology to aerospace systems; 2) act as pathfinder by demonstrating to the research community what can be done (high-potential, high-risk research); 3) help in identifying future directions of research in support of the aeronautical and space missions of the twenty-first century; and 4) help in the rapid transfer of research results to industry and in broadening awareness among researchers and engineers of the state-of-the-art in applications of advanced computational technology to the analysis, design prototyping and operations of aerospace and other high-performance engineering systems. In addition to research, Center activities include helping in the planning and coordination of the activities of a multi-center team of NASA and JPL researchers who are developing an intelligent synthesis environment for future aerospace systems; organizing workshops and national symposia; as well as writing state-of-the-art monographs and NASA special publications on timely topics.

  16. Quantum and classical dynamics in adiabatic computation

    NASA Astrophysics Data System (ADS)

    Crowley, P. J. D.; ?uri?, T.; Vinci, W.; Warburton, P. A.; Green, A. G.

    2014-10-01

    Adiabatic transport provides a powerful way to manipulate quantum states. By preparing a system in a readily initialized state and then slowly changing its Hamiltonian, one may achieve quantum states that would otherwise be inaccessible. Moreover, a judicious choice of final Hamiltonian whose ground state encodes the solution to a problem allows adiabatic transport to be used for universal quantum computation. However, the dephasing effects of the environment limit the quantum correlations that an open system can support and degrade the power of such adiabatic computation. We quantify this effect by allowing the system to evolve over a restricted set of quantum states, providing a link between physically inspired classical optimization algorithms and quantum adiabatic optimization. This perspective allows us to develop benchmarks to bound the quantum correlations harnessed by an adiabatic computation. We apply these to the D-Wave Vesuvius machine with revealingthough inconclusiveresults.

  17. Blind Quantum Computation without Trusted Center

    E-print Network

    Shih-Min Hung; Tzonelih Hwang

    2015-09-19

    Blind quantum computation (BQC) protocol allows a client having partially quantum ability to del- egate his quantum computation to a remote quantum server without leaking any information about the input, the output and the intended computation. Recently, many BQC protocols have been proposed with the intention to make the ability of client more classical. In this paper, we propose two BQC protocols, in which the client does not have to generate photons, but only has to perform either rotation or reorder on the received photons.

  18. Quantum Computing and the Jones Polynomial

    E-print Network

    Louis H. Kauffman

    2001-05-31

    This paper is an exploration of relationships between the Jones polynomial and quantum computing. We discuss the structure of the Jones polynomial in relation to representations of the Temperley Lieb algebra, and give an example of a unitary representation of the braid group. We discuss the evaluation of the polynomial as a generalized quantum amplitude and show how the braiding part of the evaluation can be construed as a quantum computation when the braiding representation is unitary. The question of an efficient quantum algorithm for computing the whole polynomial remains open.

  19. Exponential rise of dynamical complexity in quantum computing through projections.

    PubMed

    Burgarth, Daniel Klaus; Facchi, Paolo; Giovannetti, Vittorio; Nakazato, Hiromichi; Pascazio, Saverio; Yuasa, Kazuya

    2014-01-01

    The ability of quantum systems to host exponentially complex dynamics has the potential to revolutionize science and technology. Therefore, much effort has been devoted to developing of protocols for computation, communication and metrology, which exploit this scaling, despite formidable technical difficulties. Here we show that the mere frequent observation of a small part of a quantum system can turn its dynamics from a very simple one into an exponentially complex one, capable of universal quantum computation. After discussing examples, we go on to show that this effect is generally to be expected: almost any quantum dynamics becomes universal once 'observed' as outlined above. Conversely, we show that any complex quantum dynamics can be 'purified' into a simpler one in larger dimensions. We conclude by demonstrating that even local noise can lead to an exponentially complex dynamics. PMID:25300692

  20. Qubit metrology for building a fault-tolerant quantum computer

    E-print Network

    John M. Martinis

    2015-10-06

    Recent progress in quantum information has led to the start of several large national and industrial efforts to build a quantum computer. Researchers are now working to overcome many scientific and technological challenges. The program's biggest obstacle, a potential showstopper for the entire effort, is the need for high-fidelity qubit operations in a scalable architecture. This challenge arises from the fundamental fragility of quantum information, which can only be overcome with quantum error correction. In a fault-tolerant quantum computer the qubits and their logic interactions must have errors below a threshold: scaling up with more and more qubits then brings the net error probability down to appropriate levels ~ $10^{-18}$ needed for running complex algorithms. Reducing error requires solving problems in physics, control, materials and fabrication, which differ for every implementation. I explain here the common key driver for continued improvement - the metrology of qubit errors.

  1. Exponential rise of dynamical complexity in quantum computing through projections

    PubMed Central

    Burgarth, Daniel Klaus; Facchi, Paolo; Giovannetti, Vittorio; Nakazato, Hiromichi; Pascazio, Saverio; Yuasa, Kazuya

    2014-01-01

    The ability of quantum systems to host exponentially complex dynamics has the potential to revolutionize science and technology. Therefore, much effort has been devoted to developing of protocols for computation, communication and metrology, which exploit this scaling, despite formidable technical difficulties. Here we show that the mere frequent observation of a small part of a quantum system can turn its dynamics from a very simple one into an exponentially complex one, capable of universal quantum computation. After discussing examples, we go on to show that this effect is generally to be expected: almost any quantum dynamics becomes universal once observed as outlined above. Conversely, we show that any complex quantum dynamics can be purified into a simpler one in larger dimensions. We conclude by demonstrating that even local noise can lead to an exponentially complex dynamics. PMID:25300692

  2. Mathematical Aspects of Quantum Computing 2007

    NASA Astrophysics Data System (ADS)

    Nakahara, Mikio; Rahimi, Robabeh; SaiToh, Akira

    2008-04-01

    Quantum computing: an overview / M. Nakahara -- Braid group and topological quantum computing / T. Ootsuka, K. Sakuma -- An introduction to entanglement theory / D. J. H. Markham -- Holonomic quantum computing and its optimization / S. Tanimura -- Playing games in quantum mechanical settings: features of quantum games / S. K. zdemir, J. Shimamura, N. Imoto -- Quantum error-correcting codes / M. Hagiwara -- Poster summaries. Controled teleportation of an arbitrary unknown two-qubit entangled state / V. Ebrahimi, R. Rahimi, M. Nakahara. Notes on the Dr-Cirac classification / Y. Ota, M. Yoshida, I. Ohba. Bang-bang control of entanglement in Spin-Bus-Boson model / R. Rahimi, A. SaiToh, M. Nakahara. Numerical computation of time-dependent multipartite nonclassical correlation / A. SaiToh ... [et al.]. On classical no-cloning theorem under Liouville dynamics and distances / T. Yamano, O. Iguchi.

  3. Computing a Turing-Incomputable Problem from Quantum Computing

    E-print Network

    Andrs Sicard; Mario Vlez; Juan Ospina

    2003-09-26

    A hypercomputation model named Infinite Square Well Hypercomputation Model (ISWHM) is built from quantum computation. This model is inspired by the model proposed by Tien D. Kieu quant-ph/0203034 and solves an Turing-incomputable problem. For the proposed model and problem, a simulation of its behavior is made. Furthermore, it is demonstrated that ISWHM is a universal quantum computation model.

  4. Blind quantum computation protocol in which Alice only makes measurements

    E-print Network

    Tomoyuki Morimae; Keisuke Fujii

    2013-05-14

    Blind quantum computation is a new secure quantum computing protocol which enables Alice who does not have sufficient quantum technology 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. In previous protocols, Alice needs to have a device which generates quantum states, such as single-photon states. Here we propose another type of blind computing protocol where Alice does only measurements, such as the polarization measurements with a threshold detector. In several experimental setups, such as optical systems, the measurement of a state is much easier than the generation of a single-qubit state. Therefore our protocols ease Alice's burden. Furthermore, the security of our protocol is based on the no-signaling principle, which is more fundamental than quantum physics. Finally, our protocols are device independent in the sense that Alice does not need to trust her measurement device in order to guarantee the security.

  5. On Quantum Computation Theory Wim van Dam

    E-print Network

    Koolen, Marijn

    On Quantum Computation Theory Wim van Dam #12;#12;On Quantum Computation Theory #12;ILLC woensdag 9 oktober 2002, te 14.00 uur door Willem Klaas van Dam geboren te Breda. #12;Promotor: Prof. dr. P Dam, 2002 ISBN: 9057760916 #12;" . . . Many errors have been made in the world which today

  6. Fault-tolerant holonomic quantum computation

    E-print Network

    Ognyan Oreshkov; Todd A. Brun; Daniel A. Lidar

    2009-02-20

    We explain how to combine holonomic quantum computation (HQC) with fault tolerant quantum error correction. This establishes the scalability of HQC, putting it on equal footing with other models of computation, while retaining the inherent robustness the method derives from its geometric nature.

  7. Contemporary Mathematics Quantum Computing and the Jones Polynomial

    E-print Network

    Lomonaco Jr., Samuel J.

    Contemporary Mathematics Quantum Computing and the Jones Polynomial polynomial and quantum computing. We discuss the structure of the Jones polynomial in relation 5. Knot Amplitudes 6. Quantum Computing 7. Summary References

  8. Application of superconducting quantum interferometer in quantum computer development

    NASA Astrophysics Data System (ADS)

    Golovashkin, A. I.; Karuzskiy, A. L.; Orlikovskiy, A. A.; Privezentsev, V. V.; Tshovrebov, A. M.

    2008-03-01

    Various variants of use high-sensitivity superconducting quantum interferometers (SQUID) in problems closely connected with development of a quantum computer are considered. 1.Hardware realization of a method of definition of midget concentration of the paramagnetic centers, based on measurement of their magnetization SQUID in a mode of modulation microwave saturation of magnetic sublevels is offered. The method will allow make testing of semi-conductor materials necessary for creation of a spin solid-state quantum computer. 2.The opportunity of application SQUID for reading a condition of the quantum register, based on the quantum-statistical mechanism, allowing registered a state of single spin, is considered. 3.The circuit super low noise the quantum electrometer, based on use SQUID is offered as a measuring instrument of magnetization of spin system in which exchange interaction is adjusted by potential on in parallel connected managing electrodes (on type a spin ensemble computer).

  9. Multilayer microwave integrated quantum circuits for scalable quantum computing

    E-print Network

    T. Brecht; W. Pfaff; C. Wang; Y. Chu; L. Frunzio; M. H. Devoret; R. J. Schoelkopf

    2015-09-11

    As experimental quantum information processing (QIP) rapidly advances, an emerging challenge is to design a scalable architecture that combines various quantum elements into a complex device without compromising their performance. In particular, superconducting quantum circuits have successfully demonstrated many of the requirements for quantum computing, including coherence levels that approach the thresholds for scaling. However, it remains challenging to couple a large number of circuit components through controllable channels while suppressing any other interactions. We propose a hardware platform intended to address these challenges, which combines the advantages of integrated circuit fabrication and long coherence times achievable in three-dimensional circuit quantum electrodynamics (3D cQED). This multilayer microwave integrated quantum circuit (MMIQC) platform provides a path toward the realization of increasingly complex superconducting devices in pursuit of a scalable quantum computer.

  10. 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.

  11. Experimental demonstration of deterministic one-way quantum computing on a NMR quantum computer

    E-print Network

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

    2010-01-14

    One-way quantum computing is an important and novel approach to quantum computation. By exploiting the existing particle-particle interactions, we report the first 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.

  12. Detected-jump-error-correcting quantum codes, quantum error designs, and quantum computation

    E-print Network

    Detected-jump-error-correcting quantum codes, quantum error designs, and quantum computation G Kognitive Systeme, Universitat Karlsruhe, D-76128, Germany 3 Department of Computer Science and Software July 2003 The recently introduced detected-jump-correcting quantum codes are capable of stabilizing

  13. Quantum computer: an appliance for playing market games

    E-print Network

    Edward W. Piotrowski; Jan Sladkowski

    2003-05-05

    Recent development in quantum computation and quantum information theory allows to extend the scope of game theory for the quantum world. The authors have recently proposed a quantum description of financial market in terms of quantum game theory. The paper contain an analysis of such markets that shows that there would be advantage in using quantum computers and quantum strategies.

  14. On the Power of Quantum Computation Umesh Vazirani \\Lambda

    E-print Network

    Vazirani, Umesh

    nomial time on a quantum computer. In view of these results it is natural to ask whether quantumOn the Power of Quantum Computation Umesh Vazirani \\Lambda Computer Science Division, University perturbations. This property of quantum computations is used to establish that quantum circuits are ro bust

  15. Ancilla-driven universal quantum computing Vlad Gheorghiu

    E-print Network

    Griffiths, Robert B.

    Ancilla-driven universal quantum computing Vlad Gheorghiu Department of Physics Carnegie Mellon quantum computing September 30, 2010 1 / 11 #12;Outline 1 Introduction to universal quantum computing) Ancilla-driven universal quantum computing September 30, 2010 2 / 11 #12;Introduction to universal quantum

  16. Determine Ramsey numbers on a quantum computer

    E-print Network

    Hefeng Wang

    2015-10-07

    We present a quantum algorithm for computing the Ramsey numbers whose computational complexity grows super-exponentially with the number of vertices of a graph on a classical computer. The problem is mapped to a decision problem on a quantum computer, 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 determining whether the probe qubit exhibits resonance dynamics. The algorithm shows a quadratic speedup over its classical counterparts, and the degenerate ground state problem in the adiabatic quantum evolution algorithm for this problem is avoided.

  17. Evolutionary Design in Biological Quantum Computing

    E-print Network

    Gabor Vattay; Stuart A. Kauffman

    2013-11-19

    The unique capability of quantum mechanics to evolve alternative possibilities in parallel is appealing and over the years a number of quantum algorithms have been developed offering great computational benefits. Systems coupled to the environment lose quantum coherence quickly and realization of schemes based on unitarity might be impossible. Recent discovery of room temperature quantum coherence in light harvesting complexes opens up new possibilities to borrow concepts from biology to use quantum effects for computational purposes. While it has been conjectured that light harvesting complexes such as the Fenna-Matthews-Olson (FMO) complex in the green sulfur bacteria performs an efficient quantum search similar to the quantum Grover's algorithm the analogy has yet to be established. In this work we show that quantum dissipation plays an essential role in the quantum search performed in the FMO complex and it is fundamentally different from known algorithms. In the FMO complex not just the optimal level of phase breaking is present to avoid both quantum localization and Zeno trapping but it can harness quantum dissipation as well to speed the process even further up. With detailed quantum calculations taking into account both phase breaking and quantum dissipation we show that the design of the FMO complex has been evolutionarily optimized and works faster than pure quantum or classical-stochastic algorithms. Inspired by the findings we introduce a new computational concept based on decoherent quantum evolution. While it is inspired by light harvesting systems, the new computational devices can also be realized on different material basis opening new magnitude scales for miniaturization and speed.

  18. Quantum optics: Science and technology in a new light

    NASA Astrophysics Data System (ADS)

    Walmsley, I. A.

    2015-05-01

    Light facilitates exploration of quantum phenomena that illuminate the basic properties of nature and also enables radical new technologies based on these phenomena. The critical features of quantum light that underpin the opportunities for discovery and application are exceptionally low noise and strong correlations. Rapid progress in both science and technology has been stimulated by adopting components developed for optical telecommunications and networking, such as highly efficient detectors, integrated photonic circuits, and waveguide- or nanostructure-based nonlinear optical devices. These provide the means to generate new quantum states of light and matter of unprecedented scale, containing many photons with quantum correlations across space and time. Notably, networks with only several tens of photons are already beyond what can be efficiently analyzed by current computers.

  19. Fault tolerant dynamical decoupling for quantum computing and quantum memory

    E-print Network

    Souza, Alexandre M; Suter, Dieter

    2011-01-01

    Dynamical decoupling (DD) is a popular technique for protecting quantum information from degradation by interactions with the environment. However, unless special care is taken, unavoidable experimental errors in the control pulses used in this technique can destroy the quantum information instead of preserving it. Here, we investigate techniques for making dynamical decoupling sequences robust against different types of experimental errors while retaining good decoupling efficiency in a fluctuating environment, which poses the most challenging regime for protecting quantum information. We present experimental data from nuclear spin qubits in a solid and introduce a new DD sequence that is suitable for quantum computing and quantum memory.

  20. Infinite possibilities: Computational structures technology

    NASA Astrophysics Data System (ADS)

    Beam, Sherilee F.

    1994-12-01

    Computational Fluid Dynamics (or CFD) methods are very familiar to the research community. Even the general public has had some exposure to CFD images, primarily through the news media. However, very little attention has been paid to CST--Computational Structures Technology. Yet, no important design can be completed without it. During the first half of this century, researchers only dreamed of designing and building structures on a computer. Today their dreams have become practical realities as computational methods are used in all phases of design, fabrication and testing of engineering systems. Increasingly complex structures can now be built in even shorter periods of time. Over the past four decades, computer technology has been developing, and early finite element methods have grown from small in-house programs to numerous commercial software programs. When coupled with advanced computing systems, they help engineers make dramatic leaps in designing and testing concepts. The goals of CST include: predicting how a structure will behave under actual operating conditions; designing and complementing other experiments conducted on a structure; investigating microstructural damage or chaotic, unpredictable behavior; helping material developers in improving material systems; and being a useful tool in design systems optimization and sensitivity techniques. Applying CST to a structure problem requires five steps: (1) observe the specific problem; (2) develop a computational model for numerical simulation; (3) develop and assemble software and hardware for running the codes; (4) post-process and interpret the results; and (5) use the model to analyze and design the actual structure. Researchers in both industry and academia continue to make significant contributions to advance this technology with improvements in software, collaborative computing environments and supercomputing systems. As these environments and systems evolve, computational structures technology will evolve. By using CST in the design and operation of future structures systems, engineers will have a better understanding of how a system responds and lasts, more cost-effective methods of designing and testing models, and improved productivity. For informational and educational purposes, a videotape is being produced using both static and dynamic images from research institutions, software and hardware companies, private individuals, and historical photographs and drawings. The extensive number of CST resources indicates its widespread use. Applications run the gamut from simpler university-simulated problems to those requiring solutions on supercomputers. In some cases, an image or an animation will be mapped onto the actual structure to show the relevance of the computer model to the structure. computer image using traditional composition theories or video production requirements, often the image loses some of its original digital quality and impact when transferred to videotape. Although many CST images are currently available, those that are edited into the final project must meet two important criteria: they must complement the narration, and they must be broadcast quality when recorded on videotape.

  1. Infinite possibilities: Computational structures technology

    NASA Technical Reports Server (NTRS)

    Beam, Sherilee F.

    1994-01-01

    Computational Fluid Dynamics (or CFD) methods are very familiar to the research community. Even the general public has had some exposure to CFD images, primarily through the news media. However, very little attention has been paid to CST--Computational Structures Technology. Yet, no important design can be completed without it. During the first half of this century, researchers only dreamed of designing and building structures on a computer. Today their dreams have become practical realities as computational methods are used in all phases of design, fabrication and testing of engineering systems. Increasingly complex structures can now be built in even shorter periods of time. Over the past four decades, computer technology has been developing, and early finite element methods have grown from small in-house programs to numerous commercial software programs. When coupled with advanced computing systems, they help engineers make dramatic leaps in designing and testing concepts. The goals of CST include: predicting how a structure will behave under actual operating conditions; designing and complementing other experiments conducted on a structure; investigating microstructural damage or chaotic, unpredictable behavior; helping material developers in improving material systems; and being a useful tool in design systems optimization and sensitivity techniques. Applying CST to a structure problem requires five steps: (1) observe the specific problem; (2) develop a computational model for numerical simulation; (3) develop and assemble software and hardware for running the codes; (4) post-process and interpret the results; and (5) use the model to analyze and design the actual structure. Researchers in both industry and academia continue to make significant contributions to advance this technology with improvements in software, collaborative computing environments and supercomputing systems. As these environments and systems evolve, computational structures technology will evolve. By using CST in the design and operation of future structures systems, engineers will have a better understanding of how a system responds and lasts, more cost-effective methods of designing and testing models, and improved productivity. For informational and educational purposes, a videotape is being produced using both static and dynamic images from research institutions, software and hardware companies, private individuals, and historical photographs and drawings. The extensive number of CST resources indicates its widespread use. Applications run the gamut from simpler university-simulated problems to those requiring solutions on supercomputers. In some cases, an image or an animation will be mapped onto the actual structure to show the relevance of the computer model to the structure. Transferring the digital files to videotape presents a number of problems related to maintaining the quality of the original image, while still producing a broadcast quality videotape. Since researchers normally do not create a computer image using traditional composition theories or video production requirements, often the image loses some of its original digital quality and impact when transferred to videotape. Although many CST images are currently available, those that are edited into the final project must meet two important criteria: they must complement the narration, and they must be broadcast quality when recorded on videotape.

  2. Quantum computing and the entanglement frontier

    NASA Astrophysics Data System (ADS)

    Preskill, John

    2013-04-01

    Quantum information science explores the frontier of highly complex quantum states, the ``entanglement frontier.'' This study is motivated by the observation (widely believed but unproven) that classical systems cannot simulate highly entangled quantum systems efficiently, and we hope to hasten the day when well controlled quantum systems can perform tasks surpassing what can be done in the classical world. One way to achieve such ``quantum supremacy'' would be to run an algorithm on a quantum computer which solves a problem with a super-polynomial speedup relative to classical computers, but there may be other ways that can be achieved sooner, such as simulating exotic quantum states of strongly correlated matter. To operate a large scale quantum computer reliably we will need to overcome the debilitating effects of decoherence, which might be done using ``standard'' quantum hardware protected by quantum error-correcting codes, or by exploiting the nonabelian quantum statistics of anyons realized in solid state systems, or by combining both methods. Only by challenging the entanglement frontier will we learn whether Nature provides extravagant resources far beyond what the classical world would allow.

  3. The case for biological quantum computer elements

    NASA Astrophysics Data System (ADS)

    Baer, Wolfgang; Pizzi, Rita

    2009-05-01

    An extension to vonNeumann's analysis of quantum theory suggests self-measurement is a fundamental process of Nature. By mapping the quantum computer to the brain architecture we will argue that the cognitive experience results from a measurement of a quantum memory maintained by biological entities. The insight provided by this mapping suggests quantum effects are not restricted to small atomic and nuclear phenomena but are an integral part of our own cognitive experience and further that the architecture of a quantum computer system parallels that of a conscious brain. We will then review the suggestions for biological quantum elements in basic neural structures and address the de-coherence objection by arguing for a self- measurement event model of Nature. We will argue that to first order approximation the universe is composed of isolated self-measurement events which guaranties coherence. Controlled de-coherence is treated as the input/output interactions between quantum elements of a quantum computer and the quantum memory maintained by biological entities cognizant of the quantum calculation results. Lastly we will present stem-cell based neuron experiments conducted by one of us with the aim of demonstrating the occurrence of quantum effects in living neural networks and discuss future research projects intended to reach this objective.

  4. Quantum computing: pro and con BY JOHN PRESKILL

    E-print Network

    Preskill, John

    Quantum computing: pro and con BY JOHN PRESKILL Charles C. Lauritsen Laboratory of High Energy computation. Broad and important applications must be found to justify construction of a quantum computer; I-tolerant procedures that enable a quantum computer with noisy gates to perform reliably. Quantum computing hardware

  5. Ultrafast Pulse Shaping Approaches to Quantum Computing

    E-print Network

    Debabrata Goswami

    2003-12-24

    Quantum computing exploits the quantum-mechanical nature of matter to exist in multiple possible states simultaneously. This new approach promises to revolutionize the present form of computing. As an approach to quantum computing, we discuss ultrafast laser pulse shaping, in particular, the acousto-optic modulator based Fourier-Transform pulse-shaper, which has the ability to modulate tunable high power ultrafast laser pulses. We show that optical pulse shaping is an attractive route to quantum computing since shaped pulses can be transmitted over optical hardware and the same infrastructure can be used for computation and optical information transfer. We also address the problem of extending coherence-times for optically induced processes.

  6. 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.

  7. 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.

  8. Quantum computing and information extraction for a dynamical quantum system

    E-print Network

    Giuliano Benenti; Giulio Casati; Simone Montangero

    2004-02-02

    We discuss the simulation of a complex dynamical system, the so-called quantum sawtooth map model, on a quantum computer. We show that a quantum computer can be used to efficiently extract relevant physical information for this model. It is possible to simulate the dynamical localization of classical chaos and extract the localization length of the system with quadratic speed up with respect to any known classical computation. We can also compute with algebraic speed up the diffusion coefficient and the diffusion exponent both in the regimes of Brownian and anomalous diffusion. Finally, we show that it is possible to extract the fidelity of the quantum motion, which measures the stability of the system under perturbations, with exponential speed up.

  9. Non-Mechanism in Quantum Oracle Computing

    E-print Network

    Giuseppe Castagnoli

    1999-02-08

    A typical oracle problem is finding which software program is installed on a computer, by running the computer and testing its input-output behaviour. The program is randomly chosen from a set of programs known to the problem solver. As well known, some oracle problems are solved more efficiently by using quantum algorithms; this naturally implies changing the computer to quantum, while the choice of the software program remains sharp. In order to highlight the non-mechanistic origin of this higher efficiency, also the uncertainty about which program is installed must be represented in a quantum way.

  10. Computer technologies and institutional memory

    NASA Technical Reports Server (NTRS)

    Bell, Christopher; Lachman, Roy

    1989-01-01

    NASA programs for manned space flight are in their 27th year. Scientists and engineers who worked continuously on the development of aerospace technology during that period are approaching retirement. The resulting loss to the organization will be considerable. Although this problem is general to the NASA community, the problem was explored in terms of the institutional memory and technical expertise of a single individual in the Man-Systems division. The main domain of the expert was spacecraft lighting, which became the subject area for analysis in these studies. The report starts with an analysis of the cumulative expertise and institutional memory of technical employees of organizations such as NASA. A set of solutions to this problem are examined and found inadequate. Two solutions were investigated at length: hypertext and expert systems. Illustrative examples were provided of hypertext and expert system representation of spacecraft lighting. These computer technologies can be used to ameliorate the problem of the loss of invaluable personnel.

  11. Foundations of Quantum Mechanics and Quantum Computation

    NASA Astrophysics Data System (ADS)

    Aspect, Alain; Leggett, Anthony; Preskill, John; Durt, Thomas; Pironio, Stefano

    2013-03-01

    I ask the question: What can we infer about the nature and structure of the physical world (a) from experiments already done to test the predictions of quantum mechanics (b) from the assumption that all future experiments will agree with those predictions? I discuss existing and projected experiments related to the two classic paradoxes of quantum mechanics, named respectively for EPR and Schrdinger's Cat, and show in particular that one natural conclusion from both types of experiment implies the abandonment of the concept of macroscopic counterfactual definiteness.

  12. COVER IMAGE Topological quantum computation

    E-print Network

    Loss, Daniel

    fermions Without valley degeneracy Article p418 Quantum metrology The effects of noise Article p406; News 376 Quantum metrology: Beauty and the noisy beast Lorenzo Maccone and Vittorio Giovannetti 377 the ultimate precision limit in noisy quantum-enhanced metrology B. M. Escher, R. L. de Matos Filho and L

  13. Superradiance as a source of collective decoherence in quantum computers

    E-print Network

    Yavuz, Deniz

    Superradiance as a source of collective decoherence in quantum computers D. D. Yavuz Department.1364/JOSAB.31.002665 1. INTRODUCTION Over the last decade, quantum computing and quantum infor- mation and eigenvectors of large matrices [46]. The funda- mental building blocks of quantum computers are quantum bits

  14. Quantum Computers What is the difference between a computer and a physics

    E-print Network

    Shor, Peter W.

    Quantum Computers Peter Shor MIT #12;What is the difference between a computer and a physics. 1970). If quantum computers can be built, this would imply this "folk thesis" is probably not true. #12;Misconceptions about Quantum Computers False: Quantum computers would be able to speed up all computations

  15. Computational complexity of quantum optimal control landscapes

    E-print Network

    Raj Chakrabarti; Rebing Wu; Herschel Rabitz

    2007-08-27

    We study the Hamiltonian-independent contribution to the complexity of quantum optimal control problems. The optimization of controls that steer quantum systems to desired objectives can itself be considered a classical dynamical system that executes an analog computation. The system-independent component of the equations of motion of this dynamical system can be integrated analytically for various classes of discrete quantum control problems. For the maximization of observable expectation values from an initial pure state and the maximization of the fidelity of quantum gates, the time complexity of the corresponding computation belongs to the class continuous log (CLOG), the lowest analog complexity class, equivalent to the discrete complexity class NC. The simple scaling of the Hamiltonian-independent contribution to these problems with quantum system dimension indicates that with appropriately designed search algorithms, quantum optimal control can be rendered efficient even for large systems.

  16. 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.

  17. Iterated Gate Teleportation and Blind Quantum Computation.

    PubMed

    Prez-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

  18. Iterated Gate Teleportation and Blind Quantum Computation

    NASA Astrophysics Data System (ADS)

    Prez-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.

  19. Types for Quantum Computing Ross Duncan

    E-print Network

    Gay, Simon

    demonstrate how these representations may be used to reason about the behaviour of quantum computational the work of Kelly and Laplaza to give a representation theorem for the free compact closed cat- egory

  20. Fault tolerance for holonomic quantum computation

    E-print Network

    Ognyan Oreshkov; Todd A. Brun; Daniel A. Lidar

    2013-12-01

    We review an approach to fault-tolerant holonomic quantum computation on stabilizer codes. We explain its workings as based on adiabatic dragging of the subsystem containing the logical information around suitable loops along which the information remains protected.

  1. Second order error correction in quantum computing

    E-print Network

    Sheldon, Sarah (Sarah Elizabeth)

    2008-01-01

    Error correction codes are necessary for the development of reliable quantum computers. Such codes can prevent the lost of information from decoherence caused by external perturbations. This thesis evaluates a five qubit ...

  2. 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

  3. Quantum Computing and Shor`s Factoring Algorithm

    E-print Network

    Igor V. Volovich

    2001-09-02

    Lectures on quantum computing. Contents: Algorithms. Quantum circuits. Quantum Fourier transform. Elements of number theory. Modular exponentiation. Shor`s algorithm for finding the order. Computational complexity of Schor`s algorithm. Factoring integers. NP-complete problems.

  4. Classical signal-flow in cluster-state quantum computation

    E-print Network

    Kazuto Oshima

    2009-06-13

    We study concretely how classical signals should be processed in quantum cluster-state computation. Deforming corresponding quantum teleportation circuit, we find a simple rule of a classical signal-flow to obtain correct quantum computation results.

  5. Quantum Computers: Noise Propagation and Adversarial Noise Models

    E-print Network

    Kalai, Gil

    Quantum Computers: Noise Propagation and Adversarial Noise Models Gil Kalai Hebrew University that will fail quantum error correction and fault-tolerant quantum computation. We describe known results;1 Introduction The feasibility of computationally superior quantum computers is one of the most fascinating

  6. 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.

  7. Image segmentation on a quantum computer

    NASA Astrophysics Data System (ADS)

    Caraiman, Simona; Manta, Vasile I.

    2015-05-01

    In this paper, we address the field of quantum information processing and analyze the prospects of applying quantum computation concepts to image processing tasks. Specifically, we discuss the development of a quantum version for the image segmentation operation. This is an important technique that comes up in many image processing applications. We consider the threshold-based segmentation and show that a quantum circuit to achieve this operation can be built using a quantum oracle that implements the thresholding function. We discuss the circuit implementation of the oracle operator and provide examples of segmenting synthetic and real images. The main advantage of the quantum version for image segmentation over the classical approach is its speedup and is provided by the special properties of quantum information processing: superposition of states and inherent parallelism.

  8. 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

  9. Superadiabatic Controlled Evolutions and Universal Quantum Computation.

    PubMed

    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

  10. Quantum computer of wire circuit architecture

    E-print Network

    S. A. Moiseev; F. F. Gubaidullin; S. N. Andrianov

    2010-01-07

    First solid state quantum computer was built using transmons (cooper pair boxes). The operation of the computer is limited because of using a number of the rigit cooper boxes working with fixed frequency at temperatures of superconducting material. Here, we propose a novel architecture of quantum computer based on a flexible wire circuit of many coupled quantum nodes containing controlled atomic (molecular) ensembles. We demonstrate wide opportunities of the proposed computer. Firstly, we reveal a perfect storage of external photon qubits to multi-mode quantum memory node and demonstrate a reversible exchange of the qubits between any arbitrary nodes. We found optimal parameters of atoms in the circuit and self quantum modes for quantum processing. The predicted perfect storage has been observed experimentally for microwave radiation on the lithium phthalocyaninate molecule ensemble. Then also, for the first time we show a realization of the efficient basic two-qubit gate with direct coupling of two arbitrary nodes by using appropriate atomic frequency shifts in the circuit nodes. Proposed two-qubit gate runs with a speed drastically accelerated proportionally to the number of atoms in the node. The direct coupling and accelerated two-qubit gate can be realized for large number of the circuit nodes. Finally, we describe two and three-dimensional scalable architectures that pave the road to construction of universal multi-qubit quantum computer operating at room temperatures.

  11. Braid group representation on quantum computation

    NASA Astrophysics Data System (ADS)

    Aziz, Ryan Kasyfil; Muchtadi-Alamsyah, Intan

    2015-09-01

    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.

  12. Quantum Field Theory and Computational Paradigms

    NASA Astrophysics Data System (ADS)

    Krishnamurthy, E. V.; Krishnamurthy, Vikram

    We introduce the basic theory of quantization of radiation field in quantum physics and explain how it relates to the theory of recursive functions in computer science. We outline the basic differences between quantum mechanics (QM) and quantum field theory (QFT) and explain why QFT is better suited for a computational paradigm - based on algorithmic requirement, countably infinite degrees of freedom and the creation of macroscopic output objects. The quanta of the radiation field correspond to the non-negative integers and the harmonic oscillator spectra correspond to the recursive computation - with the creation and annihilation operators, respectively, playing the same role as the successor and predecessor in computability theory. Accordingly, this approach relates the classical computational model and the quantum physical model more directly than the Turing machine approach used earlier. Also, the application of Lambda calculus formalism and the associated denotational semantics (that is widely used in the classical computational paradigm involving recursive functions) for applications to computational paradigm based on quantum field theory is described. Finally, we explain where QFT and conventional paradigm depart from each other, and examine the concept of fixed points, phase transitions, programmability, emergent computation and related open problems.

  13. 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.

  14. Advanced laptop and small personal computer technology

    NASA Technical Reports Server (NTRS)

    Johnson, Roger L.

    1991-01-01

    Advanced laptop and small personal computer technology is presented in the form of the viewgraphs. The following areas of hand carried computers and mobile workstation technology are covered: background, applications, high end products, technology trends, requirements for the Control Center application, and recommendations for the future.

  15. Computing with RFID: Drivers, Technology and Implications

    E-print Network

    Roussos, George

    in that it is the first practical technology to tightly couple physical entities and digital information. In this surveyComputing with RFID: Drivers, Technology and Implications George Roussos School of Computer Science then discuss rfid and supporting network technologies, and identify their novel features and capabilities. We

  16. EDITORIAL: Quantum Computing and the Feynman Festival

    NASA Astrophysics Data System (ADS)

    Brandt, Howard E.; Kim, Young S.; Man'ko, Margarita A.

    2003-12-01

    The Feynman Festival is a new interdisciplinary conference developed for studying Richard Feynman and his physics. The first meeting of this new conference series was held at the University of Maryland on 23--28 August 2002 (http://www.physics.umd.edu/robot/feynman.html) and the second meeting is scheduled for August 2004 at the same venue. According to Feynman, the different aspects of nature are different aspects of the same thing. Therefore, the ultimate purpose of the conference is to find Feynman's same thing from all different theories. For this reason, the first meeting of the Festival did not begin with a fixed formula, but composed its scientific programme based on responses from the entire physics community. The conference drew the most enthusiastic response from the community of quantum computing, the field initiated by Feynman. Encouraged by the response, we decided to edit a special issue of Journal of Optics B: Quantum and Semiclassical Optics on quantum computing in connection with the first Feynman Festival. The authorship is not restricted to the participants of the Feynman Festival, and all interested parties were encouraged to submit their papers on this subject. Needless to say, all the papers were peer reviewed according to the well-established standards of the journal. The subject of quantum computing is not restricted to building and operating computers. It requires a deeper understanding of how quantum mechanics works in materials as well as in our minds. Indeed, it covers the basic foundations of quantum mechanics, measurement theory, information theory, quantum optics, atomic physics and condensed matter physics. It may be necessary to develop new mathematical tools to accommodate the language that nature speaks. It is gratifying to note that this special issue contains papers covering all these aspects of quantum computing. As Feynman noted, we could be discussing these diversified issues to study one problem. In our case, this `one problem' is to build quantum computers.

  17. Device-Independent Verifiable Blind Quantum Computation

    E-print Network

    Michal Hajduek; Carlos A. Prez-Delgado; Joseph F. Fitzsimons

    2015-02-09

    As progress on experimental quantum processors continues to advance, the problem of verifying the correct operation of such devices is becoming a pressing concern. Although recent progress has resulted in several protocols which can verify the output of a quantum computation performed by entangled but non-communicating processors, the overhead for such schemes is prohibitive, scaling at least as the 22nd power of the number of gates. We present a new approach based on a combination of verified blind quantum computation and Bell state self-testing. This approach has significantly reduced overhead, with resources scaling as a quartic polynomial in the number of gates.

  18. Fundamental gravitational limitations to quantum computing

    E-print Network

    Rodolfo Gambini; Rafael A. Porto; Jorge Pullin

    2005-07-27

    Lloyd has considered the ultimate limitations physics places on quantum computers. He concludes in particular that for an ``ultimate laptop'' (a computer of one liter of volume and one kilogram of mass) the maximum number of operations per second is bounded by $10^{51}$. The limit is derived considering ordinary quantum mechanics. Here we consider additional limits that are placed by quantum gravity ideas, namely the use of a relational notion of time and fundamental gravitational limits that exist on time measurements. We then particularize for the case of an ultimate laptop and show that the maximum number of operations is further constrained to $10^{47}$ per second.

  19. A distributed architecture for scalable quantum computation with realistically noisy devices

    E-print Network

    Keisuke Fujii; Takashi Yamamoto; Masato Koashi; Nobuyuki Imoto

    2012-02-29

    Tremendous efforts have been paid for realization of fault-tolerant quantum computation so far. However, preexisting fault-tolerant schemes assume that a lot of qubits live together in a single quantum system, which is incompatible with actual situations of experiment. Here we propose a novel architecture for practically scalable quantum computation, where quantum computation is distributed over small-size (four-qubit) local systems, which are connected by quantum channels. We show that the proposed architecture works even with the error probability 0.1% of local operations, which breaks through the consensus by one order of magnitude. Furthermore, the fidelity of quantum channels can be very low $\\sim$ 0.7, which substantially relaxes the difficulty of scaling-up the architecture. All key elements and their accuracy required for the present architecture are within reach of current technology. The present architecture allows us to achieve efficient scaling of quantum computer, as has been achieved in today's classical computer.

  20. Natural and artificial atoms for quantum computation

    E-print Network

    Iulia Buluta; Sahel Ashhab; Franco Nori

    2011-08-23

    Remarkable progress towards realizing quantum computation has been achieved using natural and artificial atoms as qubits. This article presents a brief overview of the current status of different types of qubits. On the one hand, natural atoms (such as neutral atoms and ions) have long coherence times, and could be stored in large arrays, providing ideal "quantum memories". On the other hand, artificial atoms (such as superconducting circuits or semiconductor quantum dots) have the advantage of custom-designed features and could be used as "quantum processing units". Natural and artificial atoms can be coupled with each other and can also be interfaced with photons for long-distance communications. Hybrid devices made of natural/artificial atoms and photons may provide the next-generation design for quantum computers.

  1. Quantum Fourier Transform in Computational Basis

    E-print Network

    S. S. Zhou; T. Loke; J. A. Izaac; J. B. Wang

    2015-11-16

    The conventional Quantum Fourier Transform, with exponential speedup compared to the classical Fast Fourier Transform, has played an important role in quantum computation as a vital part of many quantum algorithms (most prominently, the Shor's factoring algorithm). However, situations arise where it is not sufficient to encode the Fourier coefficients within the quantum amplitudes, for example in the implementation of control operations that depend on Fourier coefficients. In this paper, we detail a new quantum algorithm to encode the Fourier coefficients in the computational basis, with success probability $1-\\delta$ and desired precision $\\epsilon$. Its time complexity %$\\mathcal{O}\\big((\\log N)^2\\log(N/\\delta)/\\epsilon)\\big)$ depends polynomially on $\\log(N)$, where $N$ is the problem size, and linearly on $\\log(1/\\delta)$ and $1/\\epsilon$. We also discuss an application of potential practical importance, namely the simulation of circulant Hamiltonians.

  2. Center for Computational Structures Technology

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Perry, Ferman W.

    1995-01-01

    The Center for Computational Structures Technology (CST) is intended to serve as a focal point for the diverse CST research activities. The CST activities include the use of numerical simulation and artificial intelligence methods in modeling, analysis, sensitivity studies, and optimization of flight-vehicle structures. The Center is located at NASA Langley and is an integral part of the School of Engineering and Applied Science of the University of Virginia. The key elements of the Center are: (1) conducting innovative research on advanced topics of CST; (2) acting as pathfinder by demonstrating to the research community what can be done (high-potential, high-risk research); (3) strong collaboration with NASA scientists and researchers from universities and other government laboratories; and (4) rapid dissemination of CST to industry, through integration of industrial personnel into the ongoing research efforts.

  3. A bridge to lower overhead quantum computation

    E-print Network

    Austin G. Fowler; Simon J. Devitt

    2013-04-09

    Two primary challenges stand in the way of practical large-scale quantum computation, namely achieving sufficiently low error rate quantum gates and implementing interesting quantum algorithms with a physically reasonable number of qubits. In this work we address the second challenge, presenting a new technique, bridge compression, which enables remarkably low volume structures to be found that implement complex computations in the surface code. The surface code has a number of highly desirable properties, including the ability to achieve arbitrarily reliable computation given sufficient qubits and quantum gate error rates below approximately 1%, and the use of only a 2-D array of qubits with nearest neighbor interactions. As such, our compression technique is of great practical relevance.

  4. Scalable quantum computing based on stationary spin qubits in coupled quantum dots inside double-sided optical microcavities

    PubMed Central

    Wei, Hai-Rui; Deng, Fu-Guo

    2014-01-01

    Quantum logic gates are the key elements in quantum computing. Here we investigate the possibility of achieving a scalable and compact quantum computing based on stationary electron-spin qubits, by using the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics. We design the compact quantum circuits for implementing universal and deterministic quantum gates for electron-spin systems, including the two-qubit CNOT gate and the three-qubit Toffoli gate. They are compact and economic, and they do not require additional electron-spin qubits. Moreover, our devices have good scalability and are attractive as they both are based on solid-state quantum systems and the qubits are stationary. They are feasible with the current experimental technology, and both high fidelity and high efficiency can be achieved when the ratio of the side leakage to the cavity decay is low. PMID:25518899

  5. Computer Technology-infused Learning Enhancement

    NASA Astrophysics Data System (ADS)

    Keengwe, Jared; Anyanwu, Longy O.

    2007-10-01

    The purpose of the study was to determine students' perception of instructional integration of computer technology to improve learning. Two key questions were investigated in this study: (a) What is the students' perception of faculty integration of computer technology into classroom instruction? (b) To what extent does the students' perception of faculty integration of computer technology, students' computer proficiency levels for personal activities, and students' computer proficiency levels for instructional activities predict the students' perception of the effect of computer technology to improve learning? A survey questionnaire with a likert-type rating scale was used to collect data to answer the research questions. Descriptive statistics as well as a multiple regression technique were used to analyze data obtained in the study. A statistically significant relationship was found between the three predictor variables and the students' perception of the effect of computer technology to improve learning.

  6. A lambda calculus for quantum computation with classical control

    E-print Network

    Selinger, Peter

    A lambda calculus for quantum computation with classical control Peter Selinger, Beno^it Valiron The objective of this paper is to develop a functional programming language for quantum computers. We develop a functional programming language for quan- tum computers. Quantum computing is a theory of computation based

  7. IMS Public Lecture Are Quantum Computers The Next

    E-print Network

    Stephan, Frank

    IMS Public Lecture Are Quantum Computers The Next Generation Of Supercomputers? Jointly Organized by Abstract Quantum Computers are said to outperform all classical computers, even the classical computers of factoring large numbers, could be broken on a quantum computer. In this talk, we will see how to make sense

  8. A lambda calculus for quantum computation with classical control

    E-print Network

    Selinger, Peter

    A lambda calculus for quantum computation with classical control Peter Selinger, Beno??�t Valiron The objective of this paper is to develop a functional programming language for quantum computers. We develop a functional programming language for quan­ tum computers. Quantum computing is a theory of computation based

  9. On Block Structures in Quantum Computation

    E-print Network

    Jacobs, Bart

    MFPS 2013 On Block Structures in Quantum Computation Bart Jacobs Institute for Computing. Jacobs May 20, 2013 Abstract A block is a language construct in programming that temporarily enlarges statement. The "scope" of these local variables is then restricted to the block in which they occur

  10. 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.

  11. Early Experiences with Computational Quantum Chemistry.

    PubMed

    Pitzer, Russell M

    2011-08-01

    A description is given of the progress in computational quantum chemistry in the early 1960s, the time of the early mainframe computers. In particular, the first calculation of the barrier to internal rotation in ethane and the first molecular application of perturbed self-consistent-field equations are described with the accompanying developments, trials, and tribulations. PMID:26606608

  12. Quantum computation and analysis of Wigner and Husimi functions: Toward a quantum image treatment

    E-print Network

    Shepelyansky, Dima

    Quantum computation and analysis of Wigner and Husimi functions: Toward a quantum image treatment M cryptography, quantum tele- portation, and quantum computation. The latter takes advantage of the laws of quantum mechanics to perform computational tasks sometimes much faster than classical de- vices. A famous

  13. How Quantum Computers Fail: Quantum Codes, Correlations in Physical Systems, and Noise Accumulation

    E-print Network

    Kalai, Gil

    How Quantum Computers Fail: Quantum Codes, Correlations in Physical Systems, and Noise Accumulation Dedicated to the memory of Itamar Pitowsky Abstract The feasibility of computationally superior quantum for quantum evolutions when noise accumulates. 1 Introduction Quantum computers were offered by Feynman [6

  14. Computer Technology: State of the Art.

    ERIC Educational Resources Information Center

    Withington, Frederic G.

    1981-01-01

    Describes the nature of modern general-purpose computer systems, including hardware, semiconductor electronics, microprocessors, computer architecture, input output technology, and system control programs. Seven suggested readings are cited. (FM)

  15. Disruptive technology business models in cloud computing

    E-print Network

    Krikos, Alexis Christopher

    2010-01-01

    Cloud computing, a term whose origins have been in existence for more than a decade, has come into fruition due to technological capabilities and marketplace demands. Cloud computing can be defined as a scalable and flexible ...

  16. Construction of a universal quantum computer

    NASA Astrophysics Data System (ADS)

    Lagana, Antonio A.; Lohe, M. A.; von Smekal, Lorenz

    2009-05-01

    We construct a universal quantum computer following Deutschs original proposal of a universal quantum Turing machine (UQTM). Like Deutschs UQTM, our machine can emulate any classical Turing machine and can execute any algorithm that can be implemented in the quantum gate array framework but under the control of a quantum program, and hence is universal. We present the architecture of the machine, which consists of a memory tape and a processor and describe the observables that comprise the registers of the processor and the instruction set, which includes a set of operations that can approximate any unitary operation to any desired accuracy and hence is quantum computationally universal. We present the unitary evolution operators that act on the machine to achieve universal computation and discuss each of them in detail and specify and discuss explicit program halting and concatenation schemes. We define and describe a set of primitive programs in order to demonstrate the universal nature of the machine. These primitive programs facilitate the implementation of more complex algorithms and we demonstrate their use by presenting a program that computes the NAND function, thereby also showing that the machine can compute any classically computable function.

  17. Extending matchgates into universal quantum computation

    SciTech Connect

    Brod, Daniel J.; Galvao, Ernesto F.

    2011-08-15

    Matchgates are a family of two-qubit gates associated with noninteracting fermions. They are classically simulatable if acting only on nearest neighbors but become universal for quantum computation if we relax this restriction or use swap gates [Jozsa and Miyake, Proc. R. Soc. A 464, 3089 (2008)]. We generalize this result by proving that any nonmatchgate parity-preserving unitary is capable of extending the computational power of matchgates into universal quantum computation. We identify the single local invariant of parity-preserving unitaries responsible for this, and discuss related results in the context of fermionic systems.

  18. Dominant Strategies in Two Qubit Quantum Computations

    E-print Network

    Faisal Shah Khan

    2015-02-04

    Nash equilibrium is a solution concept in non-strictly competitive, non-cooperative game theory that finds applications in various scientific and engineering disciplines. A non-strictly competitive, non-cooperative game model is presented here for two qubit quantum computations that allows for the characterization of Nash equilibrium in these computations via the inner product of their state space. Nash equilibrium outcomes are optimal under given constraints and therefore offer a game-theoretic measure of constrained optimization of two qubit quantum computations.

  19. Quantum state transition diagram: a bridge from classical computing to quantum computing

    NASA Astrophysics Data System (ADS)

    Hook, Loyd R., IV; Lee, Samuel C.

    2010-04-01

    Very few papers have been written on the topic of a quantum version of the finite state machine, (or finite state automata). Furthermore, these papers only serve to define what a quantum finite state machine might be in the mathematical sense using the early languages of Turing machines. This paper seeks to further develop the notion of a quantum finite state machine (FSM) using constructs developed for the classical FSM and utilized for classical FSM design. In particular the quantum state transition diagram (QSTD) is constructed to further the understanding and realization of quantum finite state machines and quantum computers.

  20. Brain-Computer Interfaces and Quantum Robots

    E-print Network

    Eliano Pessa; Paola zizzi

    2009-09-08

    The actual (classical) Brain-Computer Interface attempts to use brain signals to drive suitable actuators performing the actions corresponding to subject's intention. However this goal is not fully reached, and when BCI works, it does only in particular situations. The reason of this unsatisfactory result is that intention cannot be conceived simply as a set of classical input-output relationships. It is therefore necessary to resort to quantum theory, allowing the occurrence of stable coherence phenomena, in turn underlying high-level mental processes such as intentions and strategies. More precisely, within the context of a dissipative Quantum Field Theory of brain operation it is possible to introduce generalized coherent states associated, within the framework of logic, to the assertions of a quantum metalanguage. The latter controls the quantum-mechanical computing corresponding to standard mental operation. It thus become possible to conceive a Quantum Cyborg in which a human mind controls, through a quantum metalanguage, the operation of an artificial quantum computer.

  1. Hamiltonian quantum computer in one dimension

    E-print Network

    Tzu-Chieh Wei; John C. Liang

    2015-12-21

    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 Hamiltonian quantum computer for $k=3$ with $d=5$. One implication is that simulating 1D chains of spin-2 particles is BQP-complete. 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.

  2. Fuzzy Xor Classes from Quantum Computing Anderson Avila1

    E-print Network

    Kreinovich, Vladik

    Fuzzy Xor Classes from Quantum Computing Anderson ´Avila1 , Murilo Schmalfuss1 , Renata Reiser1 modelling for fuzzy connectives and the corresponding computations of quantum states can be simultaneously and their dual constructions. So, via quantum computing not only the interpretation based on traditional quantum

  3. Robust dynamical decoupling for quantum computing and quantum memory.

    PubMed

    Souza, Alexandre M; Alvarez, Gonzalo A; Suter, Dieter

    2011-06-17

    Dynamical decoupling (DD) is a popular technique for protecting qubits from the environment. However, unless special care is taken, experimental errors in the control pulses used in this technique can destroy the quantum information instead of preserving it. Here, we investigate techniques for making DD sequences robust against different types of experimental errors while retaining good decoupling efficiency in a fluctuating environment. We present experimental data from solid-state nuclear spin qubits and introduce a new DD sequence that is suitable for quantum computing and quantum memory. PMID:21770554

  4. Robust dynamical decoupling for quantum computing and quantum memory

    E-print Network

    Alexandre M. Souza; Gonzalo A. Alvarez; Dieter Suter

    2011-06-17

    Dynamical decoupling (DD) is a popular technique for protecting qubits from the environment. However, unless special care is taken, experimental errors in the control pulses used in this technique can destroy the quantum information instead of preserving it. Here, we investigate techniques for making DD sequences robust against different types of experimental errors while retaining good decoupling efficiency in a fluctuating environment. We present experimental data from solid-state nuclear spin qubits and introduce a new DD sequence that is suitable for quantum computing and quantum memory.

  5. Quantum Computing in Non Euclidean Geometry

    E-print Network

    Germano Resconi; Ignazio Licata

    2009-11-04

    The recent debate on hyper-computation has raised new questions both on the computational abilities of quantum systems and the Church-Turing Thesis role in Physics. We propose here the idea of geometry of effective physical process as the essentially physical notion of computation. In Quantum mechanics we cannot use the traditional Euclidean geometry but we introduce more sophisticate non Euclidean geometry which include a new kind of information diffuse in the entire universe and that we can represent as Fisher information or active information. We remark that from the Fisher information we can obtain the Bohm and Hiley quantum potential and the classical Schrodinger equation. We can see the quantum phenomena do not affect a limited region of the space but is reflected in a change of the geometry of all the universe. In conclusion any local physical change or physical process is reflected in all the universe by the change of its geometry, This is the deepest meaning of the entanglement in Quantum mechanics and quantum computing. We stress the connection between metric and information as measure of change. Because computation is not restricted to calculus but is the environment changing via physical processes, super-Turing potentialities derive from an incomputable information source embedded into the geometry of the universe in accordance with Bell's constraints. In the general relativity we define the geometry of the space time. In our approach quantum phenomena define the geometry of the parameters of the probability distribution that include also the space time parameters. To study this new approach to the computation we use the new theory of Morphogenic systems.

  6. Quantum Computational Complexity John Watrous

    E-print Network

    Watrous, John

    of Computer Science University of Waterloo, Waterloo, Ontario, Canada. Article outline I. Definition computational problem. 1 #12;I Definition of the subject and its importance The inherent difficulty, or hardness and resource con- straint is that they are physically motivated. This is quite natural, given that computers

  7. Space-Efficient Simulation of Quantum Computers

    E-print Network

    Michael P. Frank; Uwe H. Meyer-Baese; Irinel Chiorescu; Liviu Oniciuc; Robert A. van Engelen

    2009-10-08

    Traditional algorithms for simulating quantum computers on classical ones require an exponentially large amount of memory, and so typically cannot simulate general quantum circuits with more than about 30 or so qubits on a typical PC-scale platform with only a few gigabytes of main memory. However, more memory-efficient simulations are possible, requiring only polynomial or even linear space in the size of the quantum circuit being simulated. In this paper, we describe one such technique, which was recently implemented at FSU in the form of a C++ program called SEQCSim, which we releasing publicly. We also discuss the potential benefits of this simulation in quantum computing research and education, and outline some possible directions for further progress.

  8. Digital photography and computer technology : a promising field of innovation 1 Digital photography and computer technology

    E-print Network

    Donsez, Didier

    Digital photography and computer technology : a promising field of innovation 1 Digital photography: (+33) 320 43 42 56 {vcord,lecomte}@lifl.fr #12;Digital photography and computer technology : a promising field of innovation 2 Digital photography and computer technology : a promising field

  9. College Students' Attitude towards Computer Technology

    ERIC Educational Resources Information Center

    Njagi, K. O.; Havice, W. L.

    2011-01-01

    Recent advances in the contemporary world, especially in the area of computer technology, have heralded the development and implementation of new and innovative teaching strategies and particularly with the Internet revolution. This study assessed students' attitude towards computer technology. Specifically, the study assessed differences in

  10. Theory-Guided Technology in Computer Science.

    ERIC Educational Resources Information Center

    Ben-Ari, Mordechai

    2001-01-01

    Examines the history of major achievements in computer science as portrayed by winners of the prestigious Turing award and identifies a possibly unique activity called Theory-Guided Technology (TGT). Researchers develop TGT by using theoretical results to create practical technology. Discusses reasons why TGT is practical in computer science and

  11. Prior Computer Experience and Technology Acceptance

    ERIC Educational Resources Information Center

    Varma, Sonali

    2010-01-01

    Prior computer experience with information technology has been identified as a key variable (Lee, Kozar, & Larsen, 2003) that can influence an individual's future use of newer computer technology. The lack of a theory driven approach to measuring prior experience has however led to conceptually different factors being used interchangeably in

  12. Computer Technology-Infused Learning Enhancement

    ERIC Educational Resources Information Center

    Keengwe, Jared; Anyanwu, Longy O.

    2007-01-01

    The purpose of the study was to determine students' perception of instructional integration of computer technology to improve learning. Two key questions were investigated in this study: (a) What is the students' perception of faculty integration of computer technology into classroom instruction? (b) To what extent does the students' perception of

  13. Simulating a perceptron on a quantum computer

    E-print Network

    Maria Schuld; Ilya Sinayskiy; Francesco Petruccione

    2014-12-11

    Perceptrons are the basic computational unit of artificial neural networks, as they model the activation mechanism of an output neuron due to incoming signals from its neighbours. As linear classifiers, they play an important role in the foundations of machine learning. In the context of the emerging field of quantum machine learning, several attempts have been made to develop a corresponding unit using quantum information theory. Based on the quantum phase estimation algorithm, this paper introduces a quantum perceptron model imitating the step-activation function of a classical perceptron. This scheme requires resources in $\\mathcal{O}(n)$ (where $n$ is the size of the input) and promises efficient applications for more complex structures such as trainable quantum neural networks.

  14. Ancilla-driven universal quantum computation

    SciTech Connect

    Anders, Janet; Browne, Dan E.; Oi, Daniel K. L.; Kashefi, Elham; Andersson, Erika

    2010-08-15

    We introduce a model of quantum computation intermediate between the gate-based and measurement-based models. A quantum register is manipulated remotely with the help of a single ancilla that ''drives'' the evolution of the register. The fully controlled ancilla qubit is coupled to the computational register only via a fixed unitary two-qubit interaction and then measured in suitable bases, driving both single- and two-qubit operations on the register. Arbitrary single-qubit operations directly on register qubits are not needed. We characterize all interactions E that induce a unitary, stepwise deterministic measurement back-action on the register sufficient to implement any quantum channel. Our scheme offers experimental advantages for computation, state preparation, and generalized measurements, since no tunable control of the register is required.

  15. Quantum Computation and Shor's Factoring Algorithm Ronald de Wolf

    E-print Network

    de Wolf, Ronald

    Quantum Computation and Shor's Factoring Algorithm Ronald de Wolf CWI and University of Amsterdam rdewolf@cwi.nl January 12, 1999 Abstract The eld of quantum computation studies the power of computers computation and to its main success so far: Peter Shor's e cient quantum algorithm for factoring integers. 1

  16. Adiabatic quantum computing with spin qubits hosted by molecules.

    PubMed

    Yamamoto, Satoru; Nakazawa, Shigeaki; Sugisaki, Kenji; Sato, Kazunobu; Toyota, Kazuo; Shiomi, Daisuke; Takui, Takeji

    2015-01-28

    A molecular spin quantum computer (MSQC) requires electron spin qubits, which pulse-based electron spin/magnetic resonance (ESR/MR) techniques can afford to manipulate for implementing quantum gate operations in open shell molecular entities. Importantly, nuclear spins, which are topologically connected, particularly in organic molecular spin systems, are client qubits, while electron spins play a role of bus qubits. Here, we introduce the implementation for an adiabatic quantum algorithm, suggesting the possible utilization of molecular spins with optimized spin structures for MSQCs. We exemplify the utilization of an adiabatic factorization problem of 21, compared with the corresponding nuclear magnetic resonance (NMR) case. Two molecular spins are selected: one is a molecular spin composed of three exchange-coupled electrons as electron-only qubits and the other an electron-bus qubit with two client nuclear spin qubits. Their electronic spin structures are well characterized in terms of the quantum mechanical behaviour in the spin Hamiltonian. The implementation of adiabatic quantum computing/computation (AQC) has, for the first time, been achieved by establishing ESR/MR pulse sequences for effective spin Hamiltonians in a fully controlled manner of spin manipulation. The conquered pulse sequences have been compared with the NMR experiments and shown much faster CPU times corresponding to the interaction strength between the spins. Significant differences are shown in rotational operations and pulse intervals for ESR/MR operations. As a result, we suggest the advantages and possible utilization of the time-evolution based AQC approach for molecular spin quantum computers and molecular spin quantum simulators underlain by sophisticated ESR/MR pulsed spin technology. PMID:25501117

  17. Verification for measurement-only blind quantum computing

    E-print Network

    Tomoyuki Morimae

    2014-06-19

    Blind quantum computing is a new secure quantum computing protocol where a client who does not have any sophisticated quantum technlogy can delegate her quantum computing to a server without leaking any privacy. It is known that a client who has only a measurement device can perform blind quantum computing [T. Morimae and K. Fujii, Phys. Rev. A {\\bf87}, 050301(R) (2013)]. It has been an open problem whether the protocol can enjoy the verification, i.e., the ability of client to check the correctness of the computing. In this paper, we propose a protocol of verification for the measurement-only blind quantum computing.

  18. Quantum computation with ``hot`` trapped ions

    SciTech Connect

    James, D.F.V.; Schneider, S. |; Milburn, G.J.

    1998-12-31

    The authors describe two methods that have been proposed to circumvent the problem of heating by external electromagnetic fields in ion trap quantum computers. Firstly the higher order modes of ion oscillation (i.e., modes other than the center-of-mass mode) have much slower heating rates, and can therefore be employed as a reliable quantum information bus. Secondly they discuss a recently proposed method combining adiabatic passage and a number-state dependent phase shift which allows quantum gates to be performed using the center-of-mass mode as the information bus, regardless of its initial state.

  19. Efficient Quantum Computing of Complex Dynamics

    E-print Network

    Giuliano Benenti; Giulio Casati; Simone Montangero; Dima L. Shepelyansky

    2001-07-06

    We propose a quantum algorithm which uses the number of qubits in an optimal way and efficiently simulates a physical model with rich and complex dynamics described by the quantum sawtooth map. The numerical study of the effect of static imperfections in the quantum computer hardware shows that the main elements of the phase space structures are accurately reproduced up to a time scale which is polynomial in the number of qubits. The errors generated by these imperfections are more dangerous than the errors of random noise in gate operations.

  20. Brain as quantum-like computer

    E-print Network

    Andrei Khrennikov

    2005-03-24

    We present a contextualist statistical realistic model for quantum-like representations in physics, cognitive science and psychology. We apply this model to describe cognitive experiments to check quantum-like structures of mental processes. The crucial role is played by interference of probabilities for mental observables. Recently one of such experiments based on recognition of images was performed. This experiment confirmed our prediction on quantum-like behaviour of mind. In our approach ``quantumness of mind'' has no direct relation to the fact that the brain (as any physical body) is composed of quantum particles. We invented a new terminology ``quantum-like (QL) mind.'' Cognitive QL-behaviour is characterized by nonzero coefficient of interference $\\lambda.$ This coefficient can be found on the basis of statistical data. There is predicted not only $\\cos \\theta$-interference of probabilities, but also hyperbolic $\\cosh \\theta$-interference. This interference was never observed for physical systems, but we could not exclude this possibility for cognitive systems. We propose a model of brain functioning as QL-computer (there is discussed difference between quantum and QL computers).

  1. Trading classical and quantum computational resources

    E-print Network

    Sergey Bravyi; Graeme Smith; John Smolin

    2015-06-03

    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 $2^{O(k)} poly(n)$. Secondly, we study Pauli-based computation (PBC) where allowed operations are non-destructive 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 $2^{O(k)} poly(n)$. Finally, we propose a purely classical algorithm that can simulate a PBC on n qubits in a time $2^{c n} poly(n)$ where $c\\approx 0.94$. This improves upon the brute-force simulation method which takes time $2^n poly(n)$. Our algorithm exploits the fact that n-fold tensor products of magic states admit a low-rank decomposition into n-qubit stabilizer states.

  2. Quantum Computing and Quantum Simulation with Group-II Atoms

    E-print Network

    Andrew J. Daley

    2011-06-28

    Recent experimental progress in controlling neutral group-II atoms for optical clocks, and in the production of degenerate gases with group-II atoms has given rise to novel opportunities to address challenges in quantum computing and quantum simulation. In these systems, it is possible to encode qubits in nuclear spin states, which are decoupled from the electronic state in the $^1$S$_0$ ground state and the long-lived $^3$P$_0$ metastable state on the clock transition. This leads to quantum computing scenarios where qubits are stored in long lived nuclear spin states, while electronic states can be accessed independently, for cooling of the atoms, as well as manipulation and readout of the qubits. The high nuclear spin in some fermionic isotopes also offers opportunities for the encoding of multiple qubits on a single atom, as well as providing an opportunity for studying many-body physics in systems with a high spin symmetry. Here we review recent experimental and theoretical progress in these areas, and summarise the advantages and challenges for quantum computing and quantum simulation with group-II atoms.

  3. Quantum Computation of Scattering in Scalar Quantum Field Theories

    E-print Network

    Stephen P. Jordan; Keith S. M. Lee; John Preskill

    2011-12-20

    Quantum field theory provides the framework for the most fundamental physical theories to be confirmed experimentally, and has enabled predictions of unprecedented precision. However, calculations of physical observables often require great computational complexity and can generally be performed only when the interaction strength is weak. A full understanding of the foundations and rich consequences of quantum field theory remains an outstanding challenge. We develop a quantum algorithm to compute relativistic scattering amplitudes in massive phi-fourth theory in spacetime of four and fewer dimensions. The algorithm runs in a time that is polynomial in the number of particles, their energy, and the desired precision, and applies at both weak and strong coupling. Thus, it offers exponential speedup over existing classical methods at high precision or strong coupling.

  4. From Computer Lab to Technology Class.

    ERIC Educational Resources Information Center

    Sherwood, Sandra

    1999-01-01

    Discussion of integrating technology into elementary school classrooms focuses on teacher training that is based on a three-year plan developed at an elementary school in Marathon, New York. Describes the role of a technology teacher who facilitates technology integration by running the computer lab, offering workshops, and developing inservice

  5. Linear Optical Quantum Computing in a Single Spatial Mode

    NASA Astrophysics Data System (ADS)

    Walmsley, Ian

    2014-05-01

    We present a scheme for linear optical quantum computing using time-bin encoded qubits in a single spatial mode. This scheme allows arbitrary numbers of qubits to be encoded in the same mode, circumventing the requirement for many spatial modes that challenges the scalability of other schemes, and exploiting the inherent stability and robustness of time-frequency optical modes. This approach leverages the architecture of modern telecommunications systems, and opens a door to very high dimensional Hilbert spaces while maintaining compact device designs. Further, temporal encodings benefit from intrinsic robustness to inhomogeneities in transmission mediums. These advantages have been recognized in works exploring the preparation of time-frequency entangled states both for tests of fundamental quantum phenomena, and for quantum communications technologies including key distribution and teleportation. Here we extend this idea to computation. In particular, we present methods for single-qubit operations and heralded controlled phase (CPhase) gates, providing a sufficient set of operations for universal quantum computing with the Knill-Laflamme-Milburn scheme. As a test of our scheme, we demonstrate the first entirely single spatial mode implementation of a two-qubit quantum gate and show its operation with an average fidelity of 0.84 /pm 0.07. An analysis of the performance of current technologies suggests that our scheme offers a promising route for the construction of quantum circuits beyond the few-qubit level. In addition, we foresee that our investigation may motivate further development of the approaches presented into a regime in which time bins are temporally overlapped and frequency based manipulations become necessary, opening up encodings of even higher densities. This work was supported by the Engineering and Physical Sciences Research Council (EP/H03031X/1), the European Commission project Q-ESSENCE (248095) and the Air Force Office of Scientific Research (European Office of Aerospace Research and Development).

  6. 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.

  7. 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.

  8. Random Numbers and Quantum Computers

    ERIC Educational Resources Information Center

    McCartney, Mark; Glass, David

    2002-01-01

    The topic of random numbers is investigated in such a way as to illustrate links between mathematics, physics and computer science. First, the generation of random numbers by a classical computer using the linear congruential generator and logistic map is considered. It is noted that these procedures yield only pseudo-random numbers since

  9. Mimicking time evolution within a quantum ground state: Ground-state quantum computation, cloning, and teleportation

    SciTech Connect

    Mizel, Ari

    2004-07-01

    Ground-state quantum computers mimic quantum-mechanical time evolution within the amplitudes of a time-independent quantum state. We explore the principles that constrain this mimicking. A no-cloning argument is found to impose strong restrictions. It is shown, however, that there is flexibility that can be exploited using quantum teleportation methods to improve ground-state quantum computer design.

  10. Quantum Computing and Lie Theory Feynman's suggestion that the only effective way to model quantum phe-

    E-print Network

    D'Agnolo, Andrea

    Quantum Computing and Lie Theory Feynman's suggestion that the only effective way to model quantum that a quantum computer could, in theory, factor large integers or do discrete logarithms in polynomial time the basic quantum mechanics necessary to understand the theory, describe quantum algorithms and explain

  11. Temporary Assumptions for Quantum Multiparty Secure Computations

    E-print Network

    J. Mueller-Quade; H. Imai

    2001-06-22

    This paper introduces quantum multiparty protocols which allow the use of temporary assumptions. We prove that secure quantum multiparty computations are possible if and only if classical multi party computations work. But these strict assumptions are necessary only during the execution of the protocol and can be loosened after termination of the protocol. We consider two settings: 1. A collusion of players tries to learn the secret inputs of honest players or tries to modify the result of the computation. 2. A collusion of players cheats in the above way or tries to disrupt the protocol, i.e., the collusion tries to abort the computation or leaks information to honest players. We give bounds on the collusions tolerable after a protocol has terminated and we state protocols reaching these bounds.

  12. Moral Responsibility and Computer Technology.

    ERIC Educational Resources Information Center

    Friedman, Batya

    Noting a recent increase in the number of cases of computer crime and computer piracy, this paper takes up the question, "How can understanding the social context of computing help us--as parents, educators, and members of government and industry--to educate young people to become morally responsible members of an electronic information

  13. Quantum chaos border for quantum computing B. Georgeot and D. L. Shepelyansky

    E-print Network

    Shepelyansky, Dima

    Quantum chaos border for quantum computing B. Georgeot and D. L. Shepelyansky Laboratoire de 20 October 1999; revised manuscript received 3 May 2000 We study a generic model of quantum computer parameter region where the efficient operation of a quantum computer remains possible. PACS number s : 05

  14. arXiv:quant-ph/9909074v317Jan2000 Quantum Chaos Border for Quantum Computing

    E-print Network

    Shepelyansky, Dima

    arXiv:quant-ph/9909074v317Jan2000 Quantum Chaos Border for Quantum Computing B. Georgeot and D. L parameter region where the efficient operation of a quantum computer remains possible. PACS numbers: 03 the effect of qubit interaction on operability of the quantum computer. The interaction is required since

  15. Towards a fullerene-based quantum computer

    E-print Network

    Simon C Benjamin; Arzhang Ardavan; G Andrew D Briggs; David A Britz; Daniel Gunlycke; John Jefferson; Mark A G Jones; David F Leigh; Brendon W Lovett; Andrei N Khlobystov; S A Lyon; John J L Morton; Kyriakos Porfyrakis; Mark R Sambrook; Alexei M Tyryshkin

    2005-11-21

    Molecular structures appear to be natural candidates for a quantum technology: individual atoms can support quantum superpositions for long periods, and such atoms can in principle be embedded in a permanent molecular scaffolding to form an array. This would be true nanotechnology, with dimensions of order of a nanometre. However, the challenges of realising such a vision are immense. One must identify a suitable elementary unit and demonstrate its merits for qubit storage and manipulation, including input / output. These units must then be formed into large arrays corresponding to an functional quantum architecture, including a mechanism for gate operations. Here we report our efforts, both experimental and theoretical, to create such a technology based on endohedral fullerenes or 'buckyballs'. We describe our successes with respect to these criteria, along with the obstacles we are currently facing and the questions that remain to be addressed.

  16. Simulation of chemical reaction dynamics on an NMR quantum computer

    E-print Network

    Dawei Lu; Nanyang Xu; Ruixue Xu; Hongwei Chen; Jiangbin Gong; Xinhua Peng; Jiangfeng Du

    2011-05-21

    Quantum simulation can beat current classical computers with minimally a few tens of qubits and will likely become the first practical use of a quantum computer. One promising application of quantum simulation is to attack challenging quantum chemistry problems. Here we report an experimental demonstration that a small nuclear-magnetic-resonance (NMR) quantum computer is already able to simulate the dynamics of a prototype chemical reaction. The experimental results agree well with classical simulations. We conclude that the quantum simulation of chemical reaction dynamics not computable on current classical computers is feasible in the near future.

  17. Computing Hypergraph Ramsey Numbers by Using Quantum Circuit

    E-print Network

    Ri Qu; Zong-shang Li; Juan Wang; Yan-ru Bao; Xiao-chun Cao

    2012-10-12

    Gaitan and Clark [Phys. Rev. Lett. 108, 010501 (2012)] have recently shown a quantum algorithm for the computation of the Ramsey numbers using adiabatic quantum evolution. We present a quantum algorithm to compute the two-color Ramsey numbers for r-uniform hypergraphs by using the quantum counting circuit.

  18. The state of quantum computer science Chris Heunen

    E-print Network

    Murawski, Andrzej

    cryptographical techniques, whose security is therefore threatened by quantum algorithms. Luckily, companiesThe state of quantum computer science Chris Heunen Computer devices using the laws of quantum mechanics are coming on to the market. Such quantum hardware can solve certain problems much more

  19. Autonomous Perceptron Neural Network Inspired from Quantum computing

    E-print Network

    M. Zidan; A. Sagheer; N. Metwally

    2015-10-02

    Recently with the rapid development of technology, there are a lot of applications require to achieve low-cost learning in order to accomplish inexpensive computation. However the known computational power of classical artificial neural networks (CANN), they are not capable to provide low-cost learning due to many reasons such as linearity, complexity of architecture, etc. In contrast, quantum neural networks (QNN) may be representing a good computational alternate to CANN, based on the computational power of quantum bit (qubit) over the classical bit. In this paper, a new algorithm of quantum perceptron neural network based only on one neuron is introduced to overcome some limitations of the classical perceptron neural networks. The proposed algorithm is capable to construct its own set of activation operators that enough to accomplish the learning process in a limited number of iterations and, consequently, reduces the cost of computation. For evaluation purpose, we utilize the proposed algorithm to solve five problems using real and artificial data. It is shown throughout the paper that promising results are provided and compared favorably with other reported algorithms

  20. Computing, Information and Communications Technology (CICT) Website

    NASA Technical Reports Server (NTRS)

    Hardman, John; Tu, Eugene (Technical Monitor)

    2002-01-01

    The Computing, Information and Communications Technology Program (CICT) was established in 2001 to ensure NASA's Continuing leadership in emerging technologies. It is a coordinated, Agency-wide effort to develop and deploy key enabling technologies for a broad range of mission-critical tasks. The NASA CICT program is designed to address Agency-specific computing, information, and communications technology requirements beyond the projected capabilities of commercially available solutions. The areas of technical focus have been chosen for their impact on NASA's missions, their national importance, and the technical challenge they provide to the Program. In order to meet its objectives, the CICT Program is organized into the following four technology focused projects: 1) Computing, Networking and Information Systems (CNIS); 2) Intelligent Systems (IS); 3) Space Communications (SC); 4) Information Technology Strategic Research (ITSR).

  1. Error correction and symmetrization in quantum computers

    E-print Network

    Asher Peres

    1996-11-26

    Errors in quantum computers are of two kinds: sudden perturbations to isolated qubits, and slow random drifts of all the qubits. The latter may be reduced, but not eliminated, by means of symmetrization, namely by using many replicas of the computer, and forcing their joint quantum state to be completely symmetric. On the other hand, isolated errors can be corrected by quantum codewords that represent a logical qubit in a redundant way, by several physical qubits. If one of the physical qubits is perturbed, for example if it gets entangled with an unknown environment, there still is enough information encoded in the other physical qubits to restore the logical qubit, and disentangle it from the environment. The recovery procedure may consist of unitary operations, without the need of actually identifying the error.

  2. Barium Ions for Quantum Computation Matthew Dietrich

    E-print Network

    Blinov, Boris

    Barium Ions for Quantum Computation Matthew Dietrich A dissertation submitted in partial of the manuscript made from microform." Signature Date #12;#12;University of Washington Abstract Barium Ions Department of Physics Barium ion is investigated as a hyperfine qubit. 137Ba+ is trapped in a linear Paul

  3. Simulations of Probabilities for Quantum Computing

    NASA Technical Reports Server (NTRS)

    Zak, M.

    1996-01-01

    It has been demonstrated that classical probabilities, and in particular, probabilistic Turing machine, can be simulated by combining chaos and non-LIpschitz dynamics, without utilization of any man-made devices (such as random number generators). Self-organizing properties of systems coupling simulated and calculated probabilities and their link to quantum computations are discussed.

  4. The quantum computer game: citizen science

    NASA Astrophysics Data System (ADS)

    Damgaard, Sidse; Mlmer, 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 Schrdinger 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.

  5. Quantum computer architecture for fast entropy extraction

    E-print Network

    Andrew M. Steane

    2002-03-11

    If a quantum computer is stabilized by fault-tolerant quantum error correction (QEC), then most of its resources (qubits and operations) are dedicated to the extraction of error information. Analysis of this process leads to a set of central requirements for candidate computing devices, in addition to the basic ones of stable qubits and controllable gates and measurements. The logical structure of the extraction process has a natural geometry and hierarchy of communication needs; a computer whose physical architecture is designed to reflect this will be able to tolerate the most noise. The relevant networks are dominated by quantum information transport, therefore to assess a computing device it is necessary to characterize its ability to transport quantum information, in addition to assessing the performance of conditional logic on nearest neighbours and the passive stability of the memory. The transport distances involved in QEC networks are estimated, and it is found that a device relying on swap operations for information transport must have those operations an order of magnitude more precise than the controlled gates of a device which can transport information at low cost.

  6. 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 parallelposing 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

  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. Quantum pathology of static internal imperfections in flawed quantum computers

    E-print Network

    Murat Cetinbas; Joshua Wilkie

    2007-05-28

    Even in the absence of external influences the operability of a quantum computer (QC) is not guaranteed because of the effects of residual one- and two-body imperfections. Here we investigate how these internal flaws affect the performance of a quantum controlled-NOT (CNOT) gate in an isolated flawed QC. First we find that the performance of the CNOT gate is considerably better when the two-body imperfections are strong. Secondly, we find that the largest source of error is due to a coherent shift rather than decoherence or dissipation. Our results suggest that the problem of internal imperfections should be given much more attention in designing scalable QC architectures.

  9. The General Quantum Interference Principle and the Duality Computer

    E-print Network

    Gui Lu Long

    2006-05-10

    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 proposed thought experiment to check the related fundamental issues, the measurement efficiency of a partial wave function

  10. (CICT) Computing, Information, and Communications Technology Overview

    NASA Technical Reports Server (NTRS)

    VanDalsem, William R.

    2003-01-01

    The goal of the Computing, Information, and Communications Technology (CICT) program is to enable NASA's Scientific Research, Space Exploration, and Aerospace Technology Missions with greater mission assurance, for less cost, with increased science return through the development and use of advanced computing, information and communications technologies. This viewgraph presentation includes diagrams of how the political guidance behind CICT is structured. The presentation profiles each part of the NASA Mission in detail, and relates the Mission to the activities of CICT. CICT's Integrated Capability Goal is illustrated, and hypothetical missions which could be enabled by CICT are profiled. CICT technology development is profiled.

  11. Controllable Coherent Population Transfers in Superconducting Qubits for Quantum Computing L. F. Wei,1,2

    E-print Network

    Nori, Franco

    Controllable Coherent Population Transfers in Superconducting Qubits for Quantum Computing L. F. Wei,1,2 J. R. Johansson,3 L. X. Cen,4 S. Ashhab,3,5 and Franco Nori1,3,5 1 CREST, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012, Japan 2 Laboratory of Quantum Opt

  12. Quantum game simulator, using the circuit model of quantum computation

    NASA Astrophysics Data System (ADS)

    Vlachos, Panagiotis; Karafyllidis, Ioannis G.

    2009-10-01

    We present a general two-player quantum game simulator that can simulate any two-player quantum game described by a 22 payoff matrix (two strategy games).The user can determine the payoff matrices for both players, their strategies and the amount of entanglement between their initial strategies. The outputs of the simulator are the expected payoffs of each player as a function of the other player's strategy parameters and the amount of entanglement. The simulator also produces contour plots that divide the strategy spaces of the game in regions in which players can get larger payoffs if they choose to use a quantum strategy against any classical one. We also apply the simulator to two well-known quantum games, the Battle of Sexes and the Chicken game. Program summaryProgram title: Quantum Game Simulator (QGS) Catalogue identifier: AEED_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEED_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 3416 No. of bytes in distributed program, including test data, etc.: 583 553 Distribution format: tar.gz Programming language: Matlab R2008a (C) Computer: Any computer that can sufficiently run Matlab R2008a Operating system: Any system that can sufficiently run Matlab R2008a Classification: 4.15 Nature of problem: Simulation of two player quantum games described by a payoff matrix. Solution method: The program calculates the matrices that comprise the Eisert setup for quantum games based on the quantum circuit model. There are 5 parameters that can be altered. We define 3 of them as constant. We play the quantum game for all possible values for the other 2 parameters and store the results in a matrix. Unusual features: The software provides an easy way of simulating any two-player quantum games. Running time: Approximately 0.4 sec (Region Feature) and 0.3 sec (Payoff Feature) on a Intel Core 2 Duo GHz with 2 GB of memory under Windows XP.

  13. Simulation of quantum computers with probabilistic Vlad Gheorghiu

    E-print Network

    Griffiths, Robert B.

    Simulation of quantum computers with probabilistic models Vlad Gheorghiu Department of Physics of quantum computers... April 6, 2010 1 / 19 #12;Outline 1 Introduction 2 Summary of main concepts.0898 [quant-ph] Vlad Gheorghiu (CMU) Simulation of quantum computers... April 6, 2010 2 / 19 #12;Introduction

  14. One Complexity Theorist's View of Quantum Computing Lance Fortnow y

    E-print Network

    Fortnow, Lance

    One Complexity Theorist's View of Quantum Computing #3; Lance Fortnow y NEC Research Institute 4 Independence Way Princeton, NJ 08540 Abstract The complexity of quantum computation remains poorly understood. While physicists at- tempt to #12;nd ways to create quantum computers, we still do not have much

  15. One Complexity Theorist's View of Quantum Computing Lance Fortnow

    E-print Network

    Fortnow, Lance

    One Complexity Theorist's View of Quantum Computing Lance Fortnow NEC Research Institute 4 Independence Way Princeton, NJ 08540 Abstract The complexity of quantum computation remains poorly understood. While physicists at- tempt to find ways to create quantum computers, we still do not have much evidence

  16. Contemporary Mathematics Quantum Computing and the Jones Polynomial

    E-print Network

    Lomonaco Jr., Samuel J.

    Contemporary Mathematics Quantum Computing and the Jones Polynomial Louis H. Kauffman Abstract. This paper is an exploration of relationships between the Jones polynomial and quantum computing. We discuss, Projectors and the Temperley Lieb Algebra 4. The Bracket Polynomial 5. Knot Amplitudes 6. Quantum Computing 7

  17. Contemporary Mathematics Quantum Computing and the Jones Polynomial

    E-print Network

    Lomonaco Jr., Samuel J.

    Contemporary Mathematics Quantum Computing and the Jones Polynomial Louis H. Kau#11;man Abstract. This paper is an exploration of relationships between the Jones polynomial and quantum computing. We discuss, Projectors and the Temperley Lieb Algebra 4. The Bracket Polynomial 5. Knot Amplitudes 6. Quantum Computing 7

  18. Hidden Translation and Orbit Coset in Quantum Computing

    E-print Network

    Fondements et Applications, Universit Paris 7

    Hidden Translation and Orbit Coset in Quantum Computing Katalin Friedl SZTAKI, Hungarian Academy solvable normal subgroup N of G. 1. INTRODUCTION Quantum computing is an extremely active research area with polynomial query complexity even if G is abelian, the biggest success of quantum computing until now

  19. ECES 753: Special Topics in Quantum Computing Spring 2008

    E-print Network

    Cahay, Marc

    ECES 753: Special Topics in Quantum Computing Spring 2008 2008 Catalog Data: 20-ECES-753 (also listed as 15-PHYS-623) Special Topics in Quantum Computing: This course is aimed at a study of advanced topics in quantum computing. Because of its cross-disciplinary nature, this class will be taught

  20. 1-qubit versus 2-qubit measurement based quantum computing

    E-print Network

    Danos, Vincent - Laboratoire Preuves, Programmes et Systmes, Universit Paris 7

    1-qubit versus 2-qubit measurement based quantum computing Vincent Danos Universite Paris 7 & CNRS and universal quantum computing model based on 2-qubit measurements (TQC), which embeds trivially in a model, then measurement, then local corrections. 1 Introduction The basic quantum computing toolkit consists of unitary

  1. Towards fault-tolerant quantum computing with trapped ions

    E-print Network

    Loss, Daniel

    LETTERS Towards fault-tolerant quantum computing with trapped ions JAN BENHELM, GERHARD KIRCHMAIR physics1,2 . For the implementation of arbitrary operations, a quantum computer requires a universal set. For ion traps, all building blocks necessary for the construction of a universal quantum computer1 have

  2. ECES 753: Special Topics in Quantum Computing Spring 2004

    E-print Network

    Cahay, Marc

    ECES 753: Special Topics in Quantum Computing Spring 2004 2003 Catalog Data: 20ECES753 (also listed as 15PHYS623) Special Topics in Quantum Computing: This course is aimed at a study of advanced topics in quantum computing. Because of its crossdisciplinary nature, this class will be taught

  3. Computer Science Colloquium Designing a Large-Scale Quantum Architecture

    E-print Network

    Computer Science Colloquium Designing a Large-Scale Quantum Architecture Speaker: Tzvetan Metodi of traditional architectures, to develop a model for a computationally relevant quantum system that provides on the development of balanced architectural models of organization and specialization for emerging quantum computing

  4. QUANTUM COMPUTATION AND REAL MULTIPLICATION MATILDE MARCOLLI AND JOHN NAPP

    E-print Network

    Marcolli, Matilde

    QUANTUM COMPUTATION AND REAL MULTIPLICATION MATILDE MARCOLLI AND JOHN NAPP Abstract. We propose, and are obtained from the basic modules and the real multiplication structure. 1. Introduction Quantum computation operations on data. It is believed that quantum computation is signifi- cantly more powerful than classical

  5. Deterministic Quantum Computation With One Photonic Qubit

    E-print Network

    M. Hor-Meyll; D. S. Tasca; S. P. Walborn; M. M. Santos; E. I. Duzzioni; P. H. Souto Ribeiro

    2015-08-05

    We show that deterministic quantum computing with one qubit (DQC1) can be experimentally implemented with a spatial light modulator, using the polarization and the transverse spatial degrees of freedom of light. The scheme allows the computation of the trace of a high dimension matrix, being limited by the resolution of the modulator panel, and the technical imperfections. In order to illustrate the method, we compute the normalized trace of unitary matrices, and implement the Deutsch-Jozsa algorithm. The largest matrix that can be manipulated with our set-up is 1080$\\times$1920, which is able to represent a system with approximately 21 qubits.

  6. Deterministic quantum computation with one photonic qubit

    NASA Astrophysics Data System (ADS)

    Hor-Meyll, M.; Tasca, D. S.; Walborn, S. P.; Ribeiro, P. H. Souto; Santos, M. M.; Duzzioni, E. I.

    2015-07-01

    We show that deterministic quantum computing with one qubit (DQC1) can be experimentally implemented with a spatial light modulator, using the polarization and the transverse spatial degrees of freedom of light. The scheme allows the computation of the trace of a high-dimension matrix, being limited by the resolution of the modulator panel and the technical imperfections. In order to illustrate the method, we compute the normalized trace of unitary matrices and implement the Deutsch-Jozsa algorithm. The largest matrix that can be manipulated with our setup is 1080 1920 , which is able to represent a system with approximately 21 qubits.

  7. Efficiency of structured adiabatic quantum computation

    E-print Network

    Juan Jose Garcia-Ripoll; Mari Carmen Bauls

    2008-12-09

    We show enough evidence that a structured version of Adiabatic Quantum Computation (AQC) is efficient for most satisfiability problems. More precisely, when the success probability is fixed beforehand, the computational resources grow subexponentially in the number of qubits. Our study focuses on random satisfiability and exact cover problems, developing a multi-step algorithm that solves clauses one by one. Relating the computational cost to classical properties of the problem, we collect significant statistics with up to N=140 qubits, around the phase transitions, which is where the hardest problems appear.

  8. Non-abelian fractional quantum hall effect for fault-resistant topological quantum computation.

    SciTech Connect

    Pan, Wei; Thalakulam, Madhu; Shi, Xiaoyan; Crawford, Matthew; Nielsen, Erik; Cederberg, Jeffrey George

    2013-10-01

    Topological quantum computation (TQC) has emerged as one of the most promising approaches to quantum computation. Under this approach, the topological properties of a non-Abelian quantum system, which are insensitive to local perturbations, are utilized to process and transport quantum information. The encoded information can be protected and rendered immune from nearly all environmental decoherence processes without additional error-correction. It is believed that the low energy excitations of the so-called =5/2 fractional quantum Hall (FQH) state may obey non-Abelian statistics. Our goal is to explore this novel FQH state and to understand and create a scientific foundation of this quantum matter state for the emerging TQC technology. We present in this report the results from a coherent study that focused on obtaining a knowledge base of the physics that underpins TQC. We first present the results of bulk transport properties, including the nature of disorder on the 5/2 state and spin transitions in the second Landau level. We then describe the development and application of edge tunneling techniques to quantify and understand the quasiparticle physics of the 5/2 state.

  9. Roadmap: Technical and Applied Studies Computer Technology Applied Computer Security and Forensics Technology-

    E-print Network

    Khan, Javed I.

    Roadmap: Technical and Applied Studies Computer Technology Applied Computer Security and Forensics Technology- Bachelor of Technical and Applied Studies RE-BTAS-TAS-CTAC Regional College Catalog Semester Five [15 Credits] ! COMT 36318 Survey of Information Security Internet Fraud and Computer

  10. Technology computer aided design characterization needs and requirements

    E-print Network

    Florida, University of

    Technology computer aided design characterization needs and requirements Mark E. Law Department 1995; accepted 2 August 1995 Technology computer aided design TCAD promises predictive calculations on the characterization community? 1996 American Vacuum Society. I. INTRODUCTION Technology computer aided design TCAD

  11. Solid State Quantum Computing Using Spectral Holes

    E-print Network

    M. S. Shahriar; P. R. Hemmer; S. Lloyd; J. A. Bowers; A. E. Craig

    2000-07-20

    A quantum computer that stores information on two-state systems called quantum bits or qubits must be able to address and manipulate individual qubits, to effect coherent interactions between pairs of qubits, and to read out the value of qubits.1,2 Current methods for addressing qubits are divided up into spatial methods, as when a laser beam is focused on an individual qubit3,4,5 or spectral methods, as when a nuclear spin in a molecule is addressed using NMR.6,7 The density of qubits addressable spatially is limited by the wavelength of light, and the number of qubits addressable spectrally is limited by spin linewidths. Here, we propose a method for addressing qubits using a method that combines spatial and spectral selectivity. The result is a design for quantum computation that provides the potential for a density of quantum information storage and processing many orders of magnitude greater than that afforded by ion traps or NMR. Specifically, this method uses an ensemble of spectrally resolved atoms in a spectral holeburning solid. The quantum oupling is provided by strong atom-cavity interaction. Using a thin disc of diamond containing nitrogen-vacancy color centers as an example, we present an explicit model for realizing up to 300 coupled qubits in a single spot. We show how about 100 operations can take place in parallel, yielding close to 40,000 operations before decoherence.

  12. Ultimate computing. Biomolecular consciousness and nano Technology

    SciTech Connect

    Hameroff, S.R.

    1987-01-01

    The book advances the premise that the cytoskeleton is the cell's nervous system, the biological controller/computer. If indeed cytoskeletal dynamics in the nanoscale (billionth meter, billionth second) are the texture of intracellular information processing, emerging ''NanoTechnologies'' (scanning tunneling microscopy, Feynman machines, von Neumann replicators, etc.) should enable direct monitoring, decoding and interfacing between biological and technological information devices. This in turn could result in important biomedical applications and perhaps a merger of mind and machine: Ultimate Computing.

  13. Beyond Computation: Information Technology, Organizational

    E-print Network

    technologies, such as the telegraph, the steam engine and the electric motor, illustrate a pattern of information that can be digitized--numbers, text, video, music, speech, programs, and engineer- ing drawings

  14. Scheme for Quantum Computing Immune to Decoherence

    NASA Technical Reports Server (NTRS)

    Williams, Colin; Vatan, Farrokh

    2008-01-01

    A constructive scheme has been devised to enable mapping of any quantum computation into a spintronic circuit in which the computation is encoded in a basis that is, in principle, immune to quantum decoherence. The scheme is implemented by an algorithm that utilizes multiple physical spins to encode each logical bit in such a way that collective errors affecting all the physical spins do not disturb the logical bit. The scheme is expected to be of use to experimenters working on spintronic implementations of quantum logic. Spintronic computing devices use quantum-mechanical spins (typically, electron spins) to encode logical bits. Bits thus encoded (denoted qubits) are potentially susceptible to errors caused by noise and decoherence. The traditional model of quantum computation is based partly on the assumption that each qubit is implemented by use of a single two-state quantum system, such as an electron or other spin-1.2 particle. It can be surprisingly difficult to achieve certain gate operations . most notably, those of arbitrary 1-qubit gates . in spintronic hardware according to this model. However, ironically, certain 2-qubit interactions (in particular, spin-spin exchange interactions) can be achieved relatively easily in spintronic hardware. Therefore, it would be fortunate if it were possible to implement any 1-qubit gate by use of a spin-spin exchange interaction. While such a direct representation is not possible, it is possible to achieve an arbitrary 1-qubit gate indirectly by means of a sequence of four spin-spin exchange interactions, which could be implemented by use of four exchange gates. Accordingly, the present scheme provides for mapping any 1-qubit gate in the logical basis into an equivalent sequence of at most four spin-spin exchange interactions in the physical (encoded) basis. The complexity of the mathematical derivation of the scheme from basic quantum principles precludes a description within this article; it must suffice to report that the derivation provides explicit constructions for finding the exchange couplings in the physical basis needed to implement any arbitrary 1-qubit gate. These constructions lead to spintronic encodings of quantum logic that are more efficient than those of a previously published scheme that utilizes a universal but fixed set of gates.

  15. Accuracy threshold for postselected quantum computation

    E-print Network

    Panos Aliferis; Daniel Gottesman; John Preskill

    2007-09-17

    We prove an accuracy threshold theorem for fault-tolerant quantum computation based on error detection and postselection. Our proof provides a rigorous foundation for the scheme suggested by Knill, in which preparation circuits for ancilla states are protected by a concatenated error-detecting code and the preparation is aborted if an error is detected. The proof applies to independent stochastic noise but (in contrast to proofs of the quantum accuracy threshold theorem based on concatenated error-correcting codes) not to strongly-correlated adversarial noise. Our rigorously established lower bound on the accuracy threshold, 1.04 \\times 10^{-3}, is well below Knill's numerical estimates.

  16. Holonomic quantum computation with electron spins in quantum dots

    SciTech Connect

    Golovach, Vitaly N.; Borhani, Massoud; Loss, Daniel

    2010-02-15

    With the help of the spin-orbit interaction, we propose a scheme to perform holonomic single-qubit gates on the electron spin confined to a quantum dot. The manipulation is done in the absence (or presence) of an applied magnetic field. By adiabatic changing the position of the confinement potential, one can rotate the spin state of the electron around the Bloch sphere in semiconductor heterostructures. The dynamics of the system is equivalent to employing an effective non-Abelian gauge potential whose structure depends on the type of the spin-orbit interaction. As an example, we find an analytic expression for the electron spin dynamics when the dot is moved around a circular path (with radius R) on the two dimensional electron gas (2DEG) and show that all single-qubit gates can be realized by tuning the radius and orientation of the circular paths. Moreover, using the Heisenberg exchange interaction, we demonstrate how one can generate two-qubit gates by bringing two quantum dots near each other, yielding a scalable scheme to perform quantum computing on arbitrary N qubits. This proposal shows a way of realizing holonomic quantum computers in solid-state systems.

  17. Schedule path optimization for quantum annealing and adiabatic quantum computing

    E-print Network

    Lishan Zeng; Jun Zhang; Mohan Sarovar

    2015-05-01

    Quantum annealing and adiabatic quantum computing have garnered much attention recently as possible models for achieving a quantum advantage over classical approaches to optimization and other special purpose computations. Both techniques are probabilistic in nature and the minimum gap between the ground state and first excited state of the system during evolution is a major factor in determining the success probability. In this work we investigate a strategy for increasing the minimum gap and success probability by introducing intermediate Hamiltonians that modify the evolution path between initial and final Hamiltonians. We focus on an optimization problem relevant to recent quantum annealing implementations and present numerical evidence for the existence of a purely local intermediate Hamiltonian that achieve the optimum performance in terms of pushing the minimum gap to one of the end points of the evolution. We further study the effectiveness of random intermediate Hamiltonians on the minimum gap and success probability, and empirically find that random Hamiltonians have a significant probability of increasing the success probability, but only by a modest amount.

  18. Information Nano-Technologies: Transition from Classical to Quantum

    E-print Network

    Alexander Yu. Vlasov

    2009-12-04

    In this presentation are discussed some problems, relevant with application of information technologies in nano-scale systems and devices. Some methods already developed in quantum information technologies may be very useful here. Here are considered two illustrative models: representation of data by quantum bits and transfer of signals in quantum wires.

  19. EDITORIAL: Progress in quantum technology: one photon at a time Progress in quantum technology: one photon at a time

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2012-07-01

    Technological developments sparked by quantum mechanics and wave-particle duality are still gaining ground over a hundred years after the theories were devised. While the impact of the theories in fundamental research, philosophy and even art and literature is widely appreciated, the implications in device innovations continue to breed potential. Applications inspired by these concepts include quantum computation and quantum cryptography protocols based on single photons, among many others. In this issue, researchers in Germany and the US report a step towards precisely triggered single-photon sources driven by surface acoustic waves (SAWs) [1]. The work brings technology based on quantum mechanics yet another step closer to practical device reality. Generation of single 'antibunched' photons has been one of the key challenges to progress in quantum information processing and communication. Researchers from Toshiba and Cambridge University in the UK recently reported what they described as 'the first electrically driven single-photon source capable of emitting indistinguishable photons' [2]. Single-photon sources have been reported previously [3]. However the approach demonstrated by Shields and colleagues allows electrical control, which is particularly useful for implementing in compact devices. The researchers used a layer of InAs quantum dots embedded in the intrinsic region of a p-i-n diode to demonstrate interference between single photons. They also present a complete theory based on the interference of photons with a Lorentzian spectrum, which they compare with both continuous-wave and pulsed experiments. The application of SAWs in achieving precisely triggered single-photon sources develops the work of researchers in Germany in the late 1990s [4]. Surface acoustic waves travel like sound waves, but are characterized by an amplitude that typically decays exponentially with depth into the substrate. As Rocke and colleagues demonstrated, they can be used to dissociate an optically excited exciton and spatially separate the electron and hole, thereby increasing the radiative lifetime by orders of magnitude. The interesting behaviour of SAWs has led to studies towards a number of other applications including sensing [5-7], synthesis and nanoassembly [8]. For applications in single-photon sources, the electron-hole pairs are transported by the SAW to a quantum dot where they recombine emitting a single photon. However, so far various limiting factors in the system, such as the low quality of the quantum dots used leading to multiple-exciton recombinations, have hindered potential applications of the system as a single-photon source. Control over high-quality quantum-dot self-assembly is constantly improving. Researchers at the University of California at Berkeley and Harvard University in the US report the ability to successfully position a small number of colloidal quantum dots to within less than 100 nm accuracy on metallic surfaces [9]. They use single-stranded DNA both to act as an anchor to the gold or silver substrates and to selectively bind to the quantum dots, allowing programmed assembly of quantum dots on plasmonic structures. More recently still, researchers in Germany have reported how they can controllably reduce the density of self-assembled InP quantum dots by cyclic deposition with growth interruptions [10]. The impressive control has great potential for quantum emitter use. In this issue, Vlk, Krenner and colleagues use an alternative approach to demonstrate how they can improve the performance of single-photon sources using SAWs. They use an optimized system of isolated self-assembled quantum posts in a quantum-well structure and inject the carriers at a distance from the posts where recombination and emission take place [3]. The SAW dissociates the electron-hole pairs and transports them to the quantum posts, so the two carrier types arrive at the quantum post with a set time delay. Other approaches, such as Coulomb blockade ones, have struggled to achieve the sequential injection of the carriers

  20. OFFICE OF INFORMATION TECHNOLOGY COMPUTER SECURITY POLICY

    E-print Network

    Walker, Lawrence R.

    Manual, Chapter 14: Data and Information Security, Section 4, Information Security Plans Physical%20-%20DATA%20AND%20INFORMATION%20SECURITY.pdf. CONTACTS Refer to the Office of Information TechnologyOFFICE OF INFORMATION TECHNOLOGY COMPUTER SECURITY POLICY RESPONsmLE ADMINISTRATOR: RESPONsm

  1. Non-unitary probabilistic quantum computing circuit and method

    NASA Technical Reports Server (NTRS)

    Williams, Colin P. (Inventor); Gingrich, Robert M. (Inventor)

    2009-01-01

    A quantum circuit performing quantum computation in a quantum computer. A chosen transformation of an initial n-qubit state is probabilistically obtained. The circuit comprises a unitary quantum operator obtained from a non-unitary quantum operator, operating on an n-qubit state and an ancilla state. When operation on the ancilla state provides a success condition, computation is stopped. When operation on the ancilla state provides a failure condition, computation is performed again on the ancilla state and the n-qubit state obtained in the previous computation, until a success condition is obtained.

  2. Computer technology forecast study for general aviation

    NASA Technical Reports Server (NTRS)

    Seacord, C. L.; Vaughn, D.

    1976-01-01

    A multi-year, multi-faceted program is underway to investigate and develop potential improvements in airframes, engines, and avionics for general aviation aircraft. The objective of this study was to assemble information that will allow the government to assess the trends in computer and computer/operator interface technology that may have application to general aviation in the 1980's and beyond. The current state of the art of computer hardware is assessed, technical developments in computer hardware are predicted, and nonaviation large volume users of computer hardware are identified.

  3. Gabrielle Allen Center for Computation & Technology

    E-print Network

    Allen, Gabrielle

    1 Gabrielle Allen Center for Computation & Technology Dept Computer Science Louisiana State hours before landfall Category 3 landfall (Peak Winds : 120 mph ) on 24th Sep, 2:40 am CDT, Texas) including wave height, period, direction of propagation, water level, surge, near surface current speed

  4. Fault-tolerant quantum computer architectures using hierarchies of quantum error-correcting codes

    E-print Network

    Cross, Andrew W. (Andrew William), 1979-

    2008-01-01

    Quantum computers have been shown to efficiently solve a class of problems for which no efficient solution is otherwise known. Physical systems can implement quantum computation, but devising realistic schemes is an extremely ...

  5. Universal quantum gates for Single Cooper Pair Box based quantum computing

    NASA Technical Reports Server (NTRS)

    Echternach, P.; Williams, C. P.; Dultz, S. C.; Braunstein, S.; Dowling, J. P.

    2000-01-01

    We describe a method for achieving arbitrary 1-qubit gates and controlled-NOT gates within the context of the Single Cooper Pair Box (SCB) approach to quantum computing. Such gates are sufficient to support universal quantum computation.

  6. Quantum computing gates via optimal control

    NASA Astrophysics Data System (ADS)

    Atia, Yosi; Elias, Yuval; Mor, Tal; Weinstein, Yossi

    2014-10-01

    We demonstrate the use of optimal control to design two entropy-manipulating quantum gates which are more complex than the corresponding, commonly used, gates, such as CNOT and Toffoli (CCNOT): A two-qubit gate called polarization exchange (PE) and a three-qubit gate called polarization compression (COMP) were designed using GRAPE, an optimal control algorithm. Both gates were designed for a three-spin system. Our design provided efficient and robust nuclear magnetic resonance (NMR) radio frequency (RF) pulses for 13C2-trichloroethylene (TCE), our chosen three-spin system. We then experimentally applied these two quantum gates onto TCE at the NMR lab. Such design of these gates and others could be relevant for near-future applications of quantum computing devices.

  7. Artificial Decoherence and its Suppression in NMR Quantum Computer

    E-print Network

    Yasushi Kondo; Mikio Nakahara; Shogo Tanimura

    2006-04-18

    Liquid-state NMR quantum computer has demonstrated the possibility of quantum computation and supported its development. Using NMR quantum computer techniques, we observed phase decoherence under two kinds of artificial noise fields; one a noise with a long period, and the other with shorter random period. The first one models decoherence in a quantum channel while the second one models transverse relaxation. We demonstrated that the bang-bang control suppresses decoherence in both cases.

  8. Blind Quantum Computing with Decoy States

    E-print Network

    Ke Xu; Hoi-kwong Lo

    2015-08-31

    In this paper, we study the Universal Blind Quantum Computing (UBQC) protocol, which allows a client to perform quantum computation on a remote quantum server and the Remote Blind qubit tate Preparation (RBSP) protocol which allows the client to prepare single qubits on the server's location with week coherent pulses. This RBSP protocol is inefficient for small $ T $, because the required number of pulses for generating one single qubit scales as $ \\mbox{O}(1/T^4) $, where $ T $ is the transmittance of the quantum channe between the client and the server. Our contribution in this paper is a modified RBSP protocol with decoy states. This new protocol allows us to generate $ S $ single qubits simultaneously in a single instance. With our new rotocol, we are able to reduce the number of weak coherent pulses required for generating one single qubit from $ \\mbox{O}(1/T^4) $ to nearly $ \\mbox{O}(1/T) $, significantly increasing the efficiency. For a 100 km standard telecom fiber of loss 0.2 dB/km, our method gives a six orders of magnitude improvement in the speed, which is very significant.

  9. Dual-code quantum computation model

    NASA Astrophysics Data System (ADS)

    Choi, Byung-Soo

    2015-08-01

    In this work, we propose the dual-code quantum computation modela fault-tolerant quantum computation scheme which alternates between two different quantum error-correction codes. Since the chosen two codes have different sets of transversal gates, we can implement a universal set of gates transversally, thereby reducing the overall cost. We use code teleportation to convert between quantum states in different codes. The overall cost is decreased if code teleportation requires fewer resources than the fault-tolerant implementation of the non-transversal gate in a specific code. To analyze the cost reduction, we investigate two cases with different base codes, namely the Steane and Bacon-Shor codes. For the Steane code, neither the proposed dual-code model nor another variation of it achieves any cost reduction since the conventional approach is simple. For the Bacon-Shor code, the three proposed variations of the dual-code model reduce the overall cost. However, as the encoding level increases, the cost reduction decreases and becomes negative. Therefore, the proposed dual-code model is advantageous only when the encoding level is low and the cost of the non-transversal gate is relatively high.

  10. Computational costs of data definition at the quantum - classical interface

    E-print Network

    Chris Fields

    2010-05-26

    Model-independent semantic requirements for user specification and interpretation of data before and after quantum computations are characterized. Classical computational costs of assigning classical data values to quantum registers and to run-time parameters passed across a classical-to-quantum application programming interface are derived. It is shown that the classical computational costs of data definition equal or exceed the classical computational cost of solving the problem of interest for all applications of quantum computing except computations defined over the integers and the simulation of linear systems with linear boundary conditions.

  11. Dynamical localization, measurements and quantum computing

    E-print Network

    M. Terraneo; D. L. Shepelyansky

    2003-09-26

    We study numerically the effects of measurements on dynamical localization in the kicked rotator model simulated on a quantum computer. Contrary to the previous studies, which showed that measurements induce a diffusive probability spreading, our results demonstrate that localization can be preserved for repeated single-qubit measurements. We detect a transition from a localized to a delocalized phase, depending on the system parameters and on the choice of the measured qubit.

  12. 2-D color code quantum computation

    E-print Network

    Austin G. Fowler

    2011-01-10

    We describe in detail how to perform universal fault-tolerant quantum computation on a 2-D color code, making use of only nearest neighbor interactions. Three defects (holes) in the code are used to represent logical qubits. Triple defect logical qubits are deformed into isolated triangular sections of color code to enable transversal implementation of all single logical qubit Clifford group gates. CNOT is implemented between pairs of triple defect logical qubits via braiding.

  13. Scalable Superconducting Architecture for Adiabatic Quantum Computation

    E-print Network

    William M. Kaminsky; Seth Lloyd; Terry P. Orlando

    2004-03-12

    A scalable superconducting architecture for adiabatic quantum computers is proposed. The architecture is based on time-independent, nearest-neighbor interqubit couplings: it can handle any problem in the class NP even in the presence of measurement errors, noise, and decoherence. The implementation of this architecture with superconducting persistent-current qubits and the natural robustness of such an implementation to manufacturing imprecision and decoherence are discussed.

  14. Simulating Factorization with a Quantum Computer

    E-print Network

    Jose Luis Rosales

    2015-05-12

    Modern cryptography is largely based on complexity assumptions, for example, the ubiquitous RSA is based on the supposed complexity of the prime factorization problem. Thus, it is of fundamental importance to understand how a quantum computer would eventually weaken these algorithms. In this paper, one follows Feynman's prescription for a computer to simulate the physics corresponding to the algorithm of factoring a large number $N$ into primes. Using Dirac-Jordan transformation theory one translates factorization into the language of quantum hermitical operators, acting on the vectors of the Hilbert space. This leads to obtaining the ensemble of factorization of $N$ in terms of the Euler function $\\varphi(N)$, that is quantized. On the other hand, considering $N$ as a parameter of the computer, a Quantum Mechanical Prime Counting Function $\\pi_{QM}(x)$, where $x$ factorizes $N$, is derived. This function converges to $\\pi(x)$ when $N\\gg x$. It has no counterpart in analytic number theory and its derivation relies on semiclassical quantization alone.

  15. Quantum computation: algorithms and implementation in quantum dot devices

    NASA Astrophysics Data System (ADS)

    Gamble, John King

    In this thesis, we explore several aspects of both the software and hardware of quantum computation. First, we examine the computational power of multi-particle quantum random walks in terms of distinguishing mathematical graphs. We study both interacting and non-interacting multi-particle walks on strongly regular graphs, proving some limitations on distinguishing powers and presenting extensive numerical evidence indicative of interactions providing more distinguishing power. We then study the recently proposed adiabatic quantum algorithm for Google PageRank, and show that it exhibits power-law scaling for realistic WWW-like graphs. Turning to hardware, we next analyze the thermal physics of two nearby 2D electron gas (2DEG), and show that an analogue of the Coulomb drag effect exists for heat transfer. In some distance and temperature, this heat transfer is more significant than phonon dissipation channels. After that, we study the dephasing of two-electron states in a single silicon quantum dot. Specifically, we consider dephasing due to the electron-phonon coupling and charge noise, separately treating orbital and valley excitations. In an ideal system, dephasing due to charge noise is strongly suppressed due to a vanishing dipole moment. However, introduction of disorder or anharmonicity leads to large effective dipole moments, and hence possibly strong dephasing. Building on this work, we next consider more realistic systems, including structural disorder systems. We present experiment and theory, which demonstrate energy levels that vary with quantum dot translation, implying a structurally disordered system. Finally, we turn to the issues of valley mixing and valley-orbit hybridization, which occurs due to atomic-scale disorder at quantum well interfaces. We develop a new theoretical approach to study these effects, which we name the disorder-expansion technique. We demonstrate that this method successfully reproduces atomistic tight-binding techniques, while using a fraction of the computational resources and providing considerably more physical insight. Using this technique, we demonstrate that large dipole moments can exist between valley states in disordered systems, and calculate corrections to intervalley tunnel rates..

  16. 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.

  17. Hybrid architecture for encoded measurement-based quantum computation

    E-print Network

    M. Zwerger; H. J. Briegel; W. Dr

    2013-08-21

    We present a hybrid scheme for quantum computation that combines the modular structure of elementary building blocks used in the circuit model with the advantages of a measurement-based approach to quantum computation. We show how to construct optimal resource states of minimal size to implement elementary building blocks for encoded quantum computation in a measurement-based way, including states for error correction and encoded gates. The performance of the scheme is determined by the quality of the resource states, where within this error model we find a threshold of the order of 10% local noise per particle for fault-tolerant quantum computation and quantum communication.

  18. Bulk Quantum Computation with Nuclear Magnetic Resonance: Theory and Experiment

    E-print Network

    Bulk Quantum Computation with Nuclear Magnetic Resonance: Theory and Experiment Isaac L. Chuang1 resonance techniques and veri ed by quantum state tomography. I. INTRODUCTION Quantum computation promise, nuclear magnetic resonance NMR 8,10,16 is particularly at- tractive because of the extremely long

  19. Insecurity of Quantum Secure Computations HoiKwong Lo \\Lambda

    E-print Network

    International Association for Cryptologic Research (IACR)

    ­party computation in classical cryptography had led to much interest in quantum cryptographic protocols [2Insecurity of Quantum Secure Computations Hoi­Kwong Lo \\Lambda BRIMS, Hewlett­Packard Labs, Filton that quantum mechanics can protect private in­ formation during public decision in for example the so

  20. Simulation of Quantum Computers H. De Raedt1

    E-print Network

    to study the functioning of Quantum Computer hardware. The latter is modeled by a collection of interacting spin-1/2 objects. The time evolution of this spin system maps one-to-one to a quantum program carried out by the Quantum Computer. Our simulation software consists of code that solves the time

  1. An Introduction to Quantum Computing using Cavity QED concepts

    E-print Network

    Zachary Burell

    2012-10-08

    We present a concise but complete conceptual treatment of quantum computing implemented with Cavity Quantum Electrodynamics (CQED. The paper is intended as a brief overview for professionals who are coming over to the field from other areas and who may have not discussed the concepts behind quantum computing during their technical training.

  2. A 2 rebit gate universal for quantum computing

    E-print Network

    Terry Rudolph; Lov Grover

    2002-10-27

    We show, within the circuit model, how any quantum computation can be efficiently performed using states with only real amplitudes (a result known within the Quantum Turing Machine model). This allows us to identify a 2-qubit (in fact 2-rebit) gate which is universal for quantum computing, although it cannot be used to perform arbitrary unitary transformations.

  3. A Geometric Algebra Perspective On Quantum Computational Gates And Universality In Quantum Computing

    E-print Network

    Carlo Cafaro; Stefano Mancini

    2010-06-10

    We investigate the utility of geometric (Clifford) algebras (GA) methods in two specific applications to quantum information science. First, using the multiparticle spacetime algebra (MSTA, the geometric algebra of a relativistic configuration space), we present an explicit algebraic description of one and two-qubit quantum states together with a MSTA characterization of one and two-qubit quantum computational gates. Second, using the above mentioned characterization and the GA description of the Lie algebras SO(3) and SU(2) based on the rotor group Spin+(3, 0) formalism, we reexamine Boykin's proof of universality of quantum gates. We conclude that the MSTA approach does lead to a useful conceptual unification where the complex qubit space and the complex space of unitary operators acting on them become united, with both being made just by multivectors in real space. Finally, the GA approach to rotations based on the rotor group does bring conceptual and computational advantages compared to standard vectorial and matricial approaches.

  4. Deterministic entanglement swapping with an ion-trap quantum computer

    E-print Network

    Loss, Daniel

    LETTERS Deterministic entanglement swapping with an ion-trap quantum computer M. RIEBE1 *, T. MONZ1 of entangled quantum systems. Here, we present our results on entangling two qubits in an ion-trap quantum in a well- defined entangled state. This particular feature may facilitate the implementation of quantum

  5. Computational Indistinguishability between Quantum States and Its Cryptographic Application

    E-print Network

    International Association for Cryptologic Research (IACR)

    Computational Indistinguishability between Quantum States and Its Cryptographic Application #3 of distinguishing between two speci#12;c quantum states as a new cryptographic problem to design a quantum cryptographic scheme that is \\secure" against any polynomial-time quantum adversary. Our problem QSCD#11

  6. Computational Indistinguishability between Quantum States and Its Cryptographic Application

    E-print Network

    International Association for Cryptologic Research (IACR)

    Computational Indistinguishability between Quantum States and Its Cryptographic Application Akinori of distinguishing between two specific quantum states as a new cryptographic problem to design a quantum cryptographic scheme that is "secure" against any polynomial-time quantum adversary. Our problem QSCDff

  7. Quantum Wavepacket Ab Initio Molecular Dynamics: An Approach for Computing Dynamically Averaged Vibrational Spectra Including Critical Nuclear Quantum Effects

    E-print Network

    Iyengar, Srinivasan S.

    Quantum Wavepacket Ab Initio Molecular Dynamics: An Approach for Computing Dynamically Averaged quantum wavepacket dynamics with ab initio molecular dynamics. The computational efficiency structure harmonic frequencies, classical ab initio molecular dynamics, computation of nuclear quantum

  8. Preparing Malaysian Vocational and Technology Teachers To Integrate Computer Technology in Teaching Vocational and Technology Subjects.

    ERIC Educational Resources Information Center

    Bakar, Ab. Rahim bin; Mohamed, Shamsiah

    1998-01-01

    A Malaysian study investigating the preparedness of vocational and technology teachers to integrate computer technology found that teachers were not knowledgeable about computers or computer software and thought they were not skillful in using spreadsheets, word processing, desktop publishing, database management, and programming software. Most

  9. many possible routes to quantum comput-ing have been suggested, but the most

    E-print Network

    Gotelli, Nicholas J.

    many possible routes to quantum comput- ing have been suggested, but the most promising are solid-intuitive rules of quantum mechanics imply that, unlike classical com- puters, quantum computers should per- form be scaled up to generate the massive parallelism required for useful computation. The counter

  10. Recent development of technologies for quantum communication

    NASA Astrophysics Data System (ADS)

    Tomita, Akihisa

    2005-01-01

    One of our major target is quantum key distribution (QKD,) which is closest to the practical use. Though QKD can be performed only with current technology, there still remain many thing to be improved. One of the most important devices that determine the system performance is photon detectors. It limits the transmission distance in optical fiber communication wavelength. A photon detector combining the two avalanche photon diodes (APD) has been demonstrated for qubit discrimination in 1550 nm. Spikes accompanied with the signals in gated-mode were canceled by balanced output from the two APDs. The balanced APD photon detector shows very low dark count rate (2x10-7) counts/pulse) with 10 % detection efficiency. We have also developed a highly stable interferometer on a planer-lightwave-circuit (PLC.) We have achieved single-photon interference over 150 km using time-division interferometers for quantum cryptography, which were composed of the two integrated-optic asymmetric Mach-Zehnder interferometers, and the balanced gated-mode photon detectors. The observed visibility was more than 80 % after 150-km transmission, which refers to a quantum bit error rate of less than 10 %. We will also describe temperature insensible QKD system and high speed (100 bps) key transmission over 40 km fiber.

  11. Cloud Computing Technologies and Applications

    NASA Astrophysics Data System (ADS)

    Zhu, Jinzy

    In a nutshell, the existing Internet provides to us content in the forms of videos, emails and information served up in web pages. With Cloud Computing, the next generation of Internet will allow us to "buy" IT services from a web portal, drastic expanding the types of merchandise available beyond those on e-commerce sites such as eBay and Taobao. We would be able to rent from a virtual storefront the basic necessities to build a virtual data center: such as CPU, memory, storage, and add on top of that the middleware necessary: web application servers, databases, enterprise server bus, etc. as the platform(s) to support the applications we would like to either rent from an Independent Software Vendor (ISV) or develop ourselves. Together this is what we call as "IT as a Service," or ITaaS, bundled to us the end users as a virtual data center.

  12. Lecture Script: Introduction to Computational Quantum Mechanics

    E-print Network

    Roman Schmied

    2015-06-05

    This document is the lecture script of a one-semester course taught at the University of Basel in the Fall semesters of 2012 and 2013 and in the Spring semester of 2015. It is aimed at advanced students of physics who are familiar with the concepts and notations of quantum mechanics. Quantum mechanics lectures can often be separated into two classes. In the first class you get to know Schroedinger's equation and find the form and dynamics of simple physical systems (square well, harmonic oscillator, hydrogen atom); most calculations are analytic and inspired by calculations originally done in the 1920s and 1930s. In the second class you learn about large systems such as molecular structures, crystalline solids, or lattice models; these calculations are usually so complicated that it is difficult for the student to understand them in all detail. This lecture tries to bridge the gap between simple analytic calculations and complicated large-scale computations. We will revisit most of the problems encountered in introductory quantum mechanics, focusing on computer implementations for finding analytical as well as numerical solutions and their visualization. Most of these calculations are too complicated to be done by hand. Even relatively simple problems, such as two interacting particles in a one-dimensional trap, do not have analytic solutions and require the use of computers for their solution and visualization. More complex problems scale exponentially with the number of degrees of freedom, and make the use of large computer simulations unavoidable. The course is taught using the Mathematica programming language; however, the concepts presented are readily translated to any other programming language.

  13. Quantum computation over the butterfly network

    E-print Network

    Akihito Soeda; Yoshiyuki Kinjo; Peter S. Turner; Mio Murao

    2011-07-14

    In order to investigate distributed quantum computation under restricted network resources, we introduce a quantum computation task over the butterfly network where both quantum and classical communications are limited. We consider deterministically performing a two-qubit global unitary operation on two unknown inputs given at different nodes, with outputs at two distinct nodes. By using a particular resource setting introduced by M. Hayashi [Phys. Rev. A \\textbf{76}, 040301(R) (2007)], which is capable of performing a swap operation by adding two maximally entangled qubits (ebits) between the two input nodes, we show that unitary operations can be performed without adding any entanglement resource, if and only if the unitary operations are locally unitary equivalent to controlled unitary operations. Our protocol is optimal in the sense that the unitary operations cannot be implemented if we relax the specifications of any of the channels. We also construct protocols for performing controlled traceless unitary operations with a 1-ebit resource and for performing global Clifford operations with a 2-ebit resource.

  14. Quantum computation over the butterfly network

    SciTech Connect

    Soeda, Akihito; Kinjo, Yoshiyuki; Turner, Peter S.; Murao, Mio

    2011-07-15

    In order to investigate distributed quantum computation under restricted network resources, we introduce a quantum computation task over the butterfly network where both quantum and classical communications are limited. We consider deterministically performing a two-qubit global unitary operation on two unknown inputs given at different nodes, with outputs at two distinct nodes. By using a particular resource setting introduced by M. Hayashi [Phys. Rev. A 76, 040301(R) (2007)], which is capable of performing a swap operation by adding two maximally entangled qubits (ebits) between the two input nodes, we show that unitary operations can be performed without adding any entanglement resource, if and only if the unitary operations are locally unitary equivalent to controlled unitary operations. Our protocol is optimal in the sense that the unitary operations cannot be implemented if we relax the specifications of any of the channels. We also construct protocols for performing controlled traceless unitary operations with a 1-ebit resource and for performing global Clifford operations with a 2-ebit resource.

  15. A general-purpose pulse sequencer for quantum computing

    E-print Network

    Phạm, Paul Tn Thế

    2005-01-01

    Quantum mechanics presents a more general and potentially more powerful model of computation than classical systems. Quantum bits have many physically different representations which nonetheless share a common need for ...

  16. Minimal computational-space implementation of multiround quantum protocols

    SciTech Connect

    Bisio, Alessandro; D'Ariano, Giacomo Mauro; Perinotti, Paolo; Chiribella, Giulio

    2011-02-15

    A single-party strategy in a multiround quantum protocol can be implemented by sequential networks of quantum operations connected by internal memories. Here, we provide an efficient realization in terms of computational-space resources.

  17. Computer Technology Program, Faculty of Science and Technology RFID Technology and Applications Research Unit, Faculty of Science and Technology

    E-print Network

    Kovintavewat, Piya

    1 Computer Technology Program, Faculty of Science and Technology 2 RFID Technology and Applications Research Unit, Faculty of Science and Technology 3 Business Computer Program, Faculty of Management Science, are essential information for customers to ensure the safety of the meat they purchased. Thailand exports

  18. Computational advantage from quantum-controlled ordering of gates.

    PubMed

    Arajo, Mateus; Costa, Fabio; Brukner, ?aslav

    2014-12-19

    It is usually assumed that a quantum computation is performed by applying gates in a specific order. One can relax this assumption by allowing a control quantum system to switch the order in which the gates are applied. This provides a more general kind of quantum computing that allows transformations on blackbox quantum gates that are impossible in a circuit with fixed order. Here we show that this model of quantum computing is physically realizable, by proposing an interferometric setup that can implement such a quantum control of the order between the gates. We show that this new resource provides a reduction in computational complexity: we propose a problem that can be solved by using O(n) blackbox queries, whereas the best known quantum algorithm with fixed order between the gates requires O(n^{2}) queries. Furthermore, we conjecture that solving this problem in a classical computer takes exponential time, which may be of independent interest. PMID:25554864

  19. Computational advantage from quantum-controlled ordering of gates

    E-print Network

    Mateus Arajo; Fabio Costa; ?aslav Brukner

    2014-12-19

    It is usually assumed that a quantum computation is performed by applying gates in a specific order. One can relax this assumption by allowing a control quantum system to switch the order in which the gates are applied. This provides a more general kind of quantum computing, that allows transformations on blackbox quantum gates that are impossible in a circuit with fixed order. Here we show that this model of quantum computing is physically realizable, by proposing an interferometric setup that can implement such a quantum control of the order between the gates. We show that this new resource provides a reduction in computational complexity: we propose a problem that can be solved using $O(n)$ blackbox queries, whereas the best known quantum algorithm with fixed order between the gates requires $O(n^2)$ queries. Furthermore, we conjecture that solving this problem in a classical computer takes exponential time, which may be of independent interest.

  20. Milestones toward Majorana-based quantum computing

    E-print Network

    David Aasen; Michael Hell; Ryan V. Mishmash; Andrew Higginbotham; Jeroen Danon; Martin Leijnse; Thomas S. Jespersen; Joshua A. Folk; Charles M. Marcus; Karsten Flensberg; Jason Alicea

    2015-11-16

    We introduce a scheme for preparation, manipulation, and readout of Majorana zero modes in semiconducting wires with mesoscopic superconducting islands. Our approach synthesizes recent advances in materials growth with tools commonly used in quantum-dot experiments, including gate-control of tunnel barriers and Coulomb effects, charge sensing, and charge pumping. We outline a sequence of milestones interpolating between zero-mode detection and quantum computing that includes (1) detection of fusion rules for non-Abelian anyons using either proximal charge sensors or pumped current; (2) validation of a prototype topological qubit; and (3) demonstration of non-Abelian statistics by braiding in a branched geometry. The first two milestones require only a single wire with two islands, and additionally enable sensitive measurements of the system's excitation gap, quasiparticle poisoning rates, residual Majorana zero-mode splittings, and topological-qubit coherence times. These pre-braiding experiments can be adapted to other manipulation and readout schemes as well.

  1. Robust Logic Gates and Realistic Quantum Computation

    E-print Network

    Li Xiao; Jonathan A. Jones

    2006-02-10

    The composite rotation approach has been used to develop a range of robust quantum logic gates, including single qubit gates and two qubit gates, which are resistant to systematic errors in their implementation. Single qubit gates based on the BB1 family of composite rotations have been experimentally demonstrated in a variety of systems, but little study has been made of their application in extended computations, and there has been no experimental study of the corresponding robust two qubit gates to date. Here we describe an application of robust gates to Nuclear Magnetic Resonance (NMR) studies of approximate quantum counting. We find that the BB1 family of robust gates is indeed useful, but that the related NB1, PB1, B4 and P4 families of tailored logic gates are less useful than initially expected.

  2. From Cbits to Qbits: Teaching computer scientists quantum mechanics

    E-print Network

    N. David Mermin

    2002-07-19

    A strategy is suggested for teaching mathematically literate students, with no background in physics, just enough quantum mechanics for them to understand and develop algorithms in quantum computation and quantum information theory. Although the article as a whole addresses teachers of physics, well versed in quantum mechanics, the central pedagogical development is addressed directly to computer scientists and mathematicians, with only occasional asides to their teacher. Physicists uninterested in quantum pedagogy may be amused (or irritated) by some of the views of standard quantum mechanics that arise naturally from this unorthodox perspective.

  3. A quantum neural network computes its own relative phase

    E-print Network

    E. C. Behrman; J. E. Steck

    2013-01-13

    Complete characterization of the state of a quantum system made up of subsystems requires determination of relative phase, because of interference effects between the subsystems. For a system of qubits used as a quantum computer this is especially vital, because the entanglement, which is the basis for the quantum advantage in computing, depends intricately on phase. We present here a first step towards that determination, in which we use a two-qubit quantum system as a quantum neural network, which is trained to compute and output its own relative phase.

  4. An Introduction to Quantum Computing for Non-Physicists

    E-print Network

    Eleanor G. Rieffel; Wolfgang Polak

    2000-01-19

    Richard Feynman's observation that quantum mechanical effects could not be simulated efficiently on a computer led to speculation that computation in general could be done more efficiently if it used quantum effects. This speculation appeared justified when Peter Shor described a polynomial time quantum algorithm for factoring integers. In quantum systems, the computational space increases exponentially with the size of the system which enables exponential parallelism. This parallelism could lead to exponentially faster quantum algorithms than possible classically. The catch is that accessing the results, which requires measurement, proves tricky and requires new non-traditional programming techniques. The aim of this paper is to guide computer scientists and other non-physicists through the conceptual and notational barriers that separate quantum computing from conventional computing. We introduce basic principles of quantum mechanics to explain where the power of quantum computers comes from and why it is difficult to harness. We describe quantum cryptography, teleportation, and dense coding. Various approaches to harnessing the power of quantum parallelism are explained, including Shor's algorithm, Grover's algorithm, and Hogg's algorithms. We conclude with a discussion of quantum error correction.

  5. Topological Quantum Computing with Only One Mobile Quasiparticle

    E-print Network

    S. H. Simon; N. E. Bonesteel; M. H. Freedman; N. Petrovic; L. Hormozi

    2006-03-07

    In a topological quantum computer, universal quantum computation is performed by dragging quasiparticle excitations of certain two dimensional systems around each other to form braids of their world lines in 2+1 dimensional space-time. In this paper we show that any such quantum computation that can be done by braiding $n$ identical quasiparticles can also be done by moving a single quasiparticle around n-1 other identical quasiparticles whose positions remain fixed.

  6. Towards Minimal Resources of Measurement-based Quantum Computation

    E-print Network

    Simon Perdrix

    2007-04-02

    We improve the upper bound on the minimal resources required for measurement-based quantum computation. Minimizing the resources required for this model is a key issue for experimental realization of a quantum computer based on projective measurements. This new upper bound allows also to reply in the negative to the open question about the existence of a trade-off between observable and ancillary qubits in measurement-based quantum computation.

  7. Efficiency of open quantum walk implementation of dissipative quantum computing algorithms

    E-print Network

    I. Sinayskiy; F. Petruccione

    2014-01-26

    An open quantum walk formalism for dissipative quantum computing is presented. The approach is illustrated with the examples of the Toffoli gate and the Quantum Fourier Transform for 3 and 4 qubits. It is shown that the algorithms based on the open quantum walk formalism are more efficient than the canonical dissipative quantum computing approach. In particular, the open quantum walks can be designed to converge faster to the desired steady state and to increase the probability of detection of the outcome of the computation.

  8. 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.

  9. Optimization strategies in measurement based quantum computation

    E-print Network

    Giulia Ferrini; Jonathan Roslund; Francesco Arzani; Yin Cai; Claude Fabre; Nicolas Treps

    2014-07-20

    This work introduces optimization strategies to continuous variable measurement based quantum computation (MBQC) at different levels. We provide a recipe for mitigating the effects of finite squeezing, which affect the production of cluster states and the result of a traditional MBQC. These strategies are readily implementable by several experimental groups. Furthermore, a more general scheme for MBQC is introduced that does not necessarily rely on the use of ancillary cluster states to achieve its aim, but rather on the detection of a resource state in a suitable mode basis followed by digital post-processing. A recipe is provided to optimize the adjustable parameters that are employed within this framework.

  10. CALIFORNIA INSTITUTE OF TECHNOLOGY Computer Science Department

    E-print Network

    Teclinoloyy Code 6.2.An Exapple 7. Utility Programs Written in Rlap 7.1 CIF to CIF 7-2Stick to CIF #12;List from 1 RLAP is en optimized CIF 2.0 file[MEAO 801 Gith user extensions for cell name2 and ports3CALIFORNIA INSTITUTE OF TECHNOLOGY Computer Science Department Silicon Structures Project SSP File

  11. Women Workers as Users of Computer Technology.

    ERIC Educational Resources Information Center

    Larwood, Laurie

    1992-01-01

    Discussion of expectations, trends, and implications of growth of computer technology and its effect on women workers argues that the experience of women is different from that of men in the nature of jobs in which women are found, their training and education, home-family conflict, and discrimination. The impact on women of increasing

  12. Business/Computer Technologies. State Competency Profile.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document contains 272 competencies, grouped into 36 units, for tech prep programs in the business/computer technology cluster. The competencies were developed through collaboration of Ohio business, industry, and labor representatives and secondary and associate degree educators. The competencies are rated either "essential" (necessary to

  13. Competency Index. [Business/Computer Technologies Cluster.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This index allows the user to scan the competencies under each title for the 28 subjects appropriate for use in a competency list for the 12 occupations within the business/computer technologies cluster. Titles of the 28 units are as follows: employability skills; professionalism; teamwork; professional and ethical standards; economic and business

  14. Instructional Technology in Computer Science Education

    ERIC Educational Resources Information Center

    Jenny, Frederick J.

    2004-01-01

    The Web, the Internet, the intranet and associated resources, campus computer labs, smart classrooms, course management systems, and a plethora of software packages all offer opportunities for every classroom instructor to enrich in-class and out-of-class activities. Why should an instructor consider the integration of technology into their

  15. Quantum Optical Technologies for Metrology, Sensing, and Imaging

    NASA Astrophysics Data System (ADS)

    Dowling, Jonathan P.; Seshadreesan, Kaushik P.

    2015-06-01

    Over the past 20 years, bright sources of entangled photons have led to a renaissance in quantum optical interferometry. Optical interferometry has been used to test the foundations of quantum mechanics and implement some of the novel ideas associated with quantum entanglement such as quantum teleportation, quantum cryptography, quantum lithography, quantum computing logic gates, and quantum metrology. In this paper, we focus on the new ways that have been developed to exploit quantum optical entanglement in quantum metrology to beat the shot-noise limit, which can be used, e.g., in fiber optical gyroscopes and in sensors for biological or chemical targets. We also discuss how this entanglement can be used to beat the Rayleigh diffraction limit in imaging systems such as in LIDAR and optical lithography.

  16. Quantum optical technologies for metrology, sensing and imaging

    E-print Network

    Jonathan P. Dowling; Kaushik P. Seshadreesan

    2015-02-27

    Over the past 20 years, bright sources of entangled photons have led to a renaissance in quantum optical interferometry. Optical interferometry has been used to test the foundations of quantum mechanics and implement some of the novel ideas associated with quantum entanglement such as quantum teleportation, quantum cryptography, quantum lithography, quantum computing logic gates, and quantum metrology. In this paper, we focus on the new ways that have been developed to exploit quantum optical entanglement in quantum metrology to beat the shot-noise limit, which can be used, e.g., in fiber optical gyroscopes and in sensors for biological or chemical targets. We also discuss how this entanglement can be used to beat the Rayleigh diffraction limit in imaging systems such as in LIDAR and optical lithography.

  17. Cavity quantum electrodynamics for superconducting electrical circuits: An architecture for quantum computation

    E-print Network

    . This architecture is attractive both as a macroscopic analog of atomic physics experiments and for quantum computingCavity quantum electrodynamics for superconducting electrical circuits: An architecture for quantum computation Alexandre Blais,1 Ren-Shou Huang,1,2 Andreas Wallraff,1 S. M. Girvin,1 and R. J. Schoelkopf1 1

  18. Computer technology forecasting at the National Laboratories

    SciTech Connect

    Peskin, A M

    1980-01-01

    The DOE Office of ADP Management organized a group of scientists and computer professionals, mostly from their own national laboratories, to prepare an annually updated technology forecast to accompany the Department's five-year ADP Plan. The activities of the task force were originally reported in an informal presentation made at the ACM Conference in 1978. This presentation represents an update of that report. It also deals with the process of applying the results obtained at a particular computing center, Brookhaven National Laboratory. Computer technology forecasting is a difficult and hazardous endeavor, but it can reap considerable advantage. The forecast performed on an industry-wide basis can be applied to the particular needs of a given installation, and thus give installation managers considerable guidance in planning. A beneficial side effect of this process is that it forces installation managers, who might otherwise tend to preoccupy themselves with immediate problems, to focus on longer term goals and means to their ends. (RWR)

  19. Computational Role of Multiqubit Tunneling in a Quantum Annealer

    E-print Network

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

    2015-02-20

    Quantum tunneling, a phenomenon in which a quantum state traverses energy barriers above the energy of the state itself, has been hypothesized as an advantageous physical resource for optimization. Here we show that multiqubit tunneling plays a computational role in a currently available, albeit noisy, programmable quantum annealer. We develop a non-perturbative theory of open quantum dynamics under realistic noise characteristics predicting the rate of many-body dissipative quantum tunneling. We devise a computational primitive with 16 qubits where quantum evolutions enable tunneling to the global minimum while the corresponding classical paths are trapped in a false minimum. Furthermore, we experimentally demonstrate that quantum tunneling can outperform thermal hopping along classical paths for problems with up to 200 qubits containing the computational primitive. Our results indicate that many-body quantum phenomena could be used for finding better solutions to hard optimization problems.

  20. Quantum Computing, NP-complete Problems and Chaotic Dynamics

    E-print Network

    Masanori Ohya; Igor V. Volovich

    1999-12-21

    An approach to the solution of NP-complete problems based on quantum computing and chaotic dynamics is proposed. We consider the satisfiability problem and argue that the problem, in principle, can be solved in polynomial time if we combine the quantum computer with the chaotic dynamics amplifier based on the logistic map. We discuss a possible implementation of such a chaotic quantum computation by using the atomic quantum computer with quantum gates described by the Hartree-Fock equations. In this case, in principle, one can build not only standard linear quantum gates but also nonlinear gates and moreover they obey to Fermi statistics. This new type of entaglement related with Fermi statistics can be interesting also for quantum communication theory.

  1. Quantum cryptographic network based on quantum memories Computer Science Department, Technion, Haifa 32000, Israel

    E-print Network

    Mor, Tal

    Quantum cryptographic network based on quantum memories Eli Biham Computer Science Department secure transmission of information. We present a quantum cryptographic system in which users store who have particles in the same center. Unlike other quantum cryptographic systems, it can work without

  2. Surface code quantum computing by lattice surgery

    E-print Network

    Horsman, Clare; Devitt, Simon; Van Meter, Rodney

    2011-01-01

    In recent years, surface codes have become the preferred method for quantum error correction in large scale computational and communications architectures. Their comparatively high fault-tolerant thresholds and their natural 2-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 surfa...

  3. EDITORIAL: Quantum science and technology at the nanoscale Quantum science and technology at the nanoscale

    NASA Astrophysics Data System (ADS)

    Demming, Anna

    2010-07-01

    The development of quantum theory was an archetypal scientific revolution in early twentieth-century physics. In many ways, the probabilities and uncertainties that replaced the ubiquitous application of classical mechanics may have seemed a violent assault on logic and reason. 'Something unknown is doing we don't know what-that is what our theory amounts to,' Sir Arthur Eddington famously remarked, adding, 'It does not sound a particularly illuminating theory. I have read something like it elsewhere: the slithy toves, did gyre and gimble in the wabe' [1]. Today, quantum mechanics no longer seems a dark art best confined to the boundaries of physics and philosophy. Scanning probe micrographs have captured actual images of quantum-mechanical interference patterns [2], and familiarity has made the claims of quantum theory more palatable. An understanding of quantum effects is essential for nanoscale science and technology research. This special issue on quantum science and technology at the nanoscale collates some of the latest research that is extending the boundaries of our knowledge and understanding in the field. Quantum phenomena have become particularly significant in attempts to further reduce the size of electronic devices, the trend widely referred to as Moore's law. In this issue, researchers in Switzerland report results from transport studies on graphene. The researchers investigate the conductance variance in systems with superconducting contacts [3]. Also in this issue, researchers in Germany calculate the effects of spin-orbit coupling in a molecular dimer and predict nonlinear transport. They also explain how ferromagnetic electrodes can be used to probe these interactions [4]. Our understanding of spin and the ability to manipulate it has advanced greatly since the notion of spin was first proposed. However, it remains the case that little is known about local coherent fluctuations of spin polarizations, the scale on which they occur, how they are correlated, and how they influence spin currents and their fluctuations, as well as the mechanisms behind current-induced spin polarizations in chaotic ballistic systems. In a theoretical report on current-induced spin polarization from the University of Arizona, progress is made in filling in some of these gaps, and a 'spin-probe' model is proposed [5]. Spin is also an important element in quantum information research. With electron spin coherence lifetimes exceeding 1 ms at room temperature, as well as the added benefit of being optically addressable, nitrogen-vacancy defects in diamond have been identified as having considerable potential for quantum information applications. Now researchers in the US describe the fabrication and low-temperature characterization of silica microdisk cavities coupled to diamond nanoparticles, and present theoretical and experimental studies of gallium phosphide structures coupled to nitrogen-vacancy centers in bulk diamond [6]. Double quantum dots have been considered as prospective candidates for charge qubits for quantum information processors. The application of a bias voltage can be used to control tunnelling between the double quantum dots, allowing the energy states to be tuned. Researchers in Switzerland investigate experimentally the effect of ohmic heating of the phonon bath on decoherence, and find that the system can be considered as a thermoelectric generator [7]. This progress has only been made possible by advances in our understanding of the fundamental science behind quantum mechanics, and work exploring this territory is still a hotbed of activity and progress. Increasingly sophisticated tools, both numerical and experimental, have facilitated engagement with quantum phenomena in nanoscale systems. Molecular spin clusters represent an ideal setting within solid-state systems to test concepts in quantum mechanics, as highlighted in this issue by researchers in Italy, who report their work on controlling entanglement between molecular spins [8]. Nanofabrication techniques have seen tremendous advances that have en

  4. Analog quantum computing (AQC) by revisiting the underlying physics

    NASA Astrophysics Data System (ADS)

    Werbos, Paul J.

    2015-05-01

    It has been proven that universal quantum computers based on qubits and classical analog networks both have superTuring capabilities. It is a grand challenge to computer science to prove that the combination of the two, in analog (continuous variable) quantum computing, offers supersuperTuring capability, the best we can achieve. Computing with continuous spins is now the most promising path AQC. Two papers at SPIE2014 described unbreakable quantum codes using continuous spins beyond what traditional qubits allow. To make this real, we must first develop a realistic ability to model and predict the behavior of networks of spin gates which act in part as polarizers. Last year I proposed a triphoton experiment, where three entangled photons go to linear polarizers set to angles ?a, ?b and ?c. Assuming a "collapse of the wave function" yields predictions for the coincidence detection rate, R3/R0(?a, ?b, ?c) significantly different from the prediction of a new family of models based on classical Markov Random Fields (MRF) across space time, even though both yield the same correct prediction in the two-photon case. We cannot expect to predict systems of 100 entangled photons correctly if we cannot even predict three yet. Yanhua Shih is currently performing this experiment, as a first step to demonstrating a new technology to produce 100 entangled photons (collaborating with Scully) and understanding larger systems. I have also developed continuous-time versions of the MRF models and of "collapse of the wave function", so as to eliminate the need to assume metaphysical observers in general.

  5. Semiconductor-inspired superconducting quantum computing

    E-print Network

    Yun-Pil Shim; Charles Tahan

    2015-07-28

    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 almost magical and very useful properties which can be utilized for spin qubit based quantum computing. Here we begin to explore how selective design principles deduced from spin-based systems could be used to advance superconducting qubit science. We take an initial step along this path proposing 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 with minimal overhead (zero overhead in 2-qubit gates), 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.

  6. Computer Technology and Counseling Psychology: Regression Toward the Machine?

    ERIC Educational Resources Information Center

    Sampson, James P., Jr.

    1986-01-01

    The current use of computer technology in counseling psychology is explored and the potential negative impact of computer technology is discussed in terms of the misuse of computer applications, dependence on technology, and restriction of the counseling process. Factors contributing to inappropriate use of technology are also discussed along with

  7. Multiple network alignment on quantum computers

    NASA Astrophysics Data System (ADS)

    Daskin, Anmer; Grama, Ananth; Kais, Sabre

    2014-09-01

    Comparative analyses of graph structured datasets underly diverse problems. Examples of these problems include identification of conserved functional components (biochemical interactions) across species, structural similarity of large biomolecules, and recurring patterns of interactions in social networks. A large class of such analyses methods quantify the topological similarity of nodes across networks. The resulting correspondence of nodes across networks, also called node alignment, can be used to identify invariant subgraphs across the input graphs. Given $k$ graphs as input, alignment algorithms use topological information to assign a similarity score to each $k$-tuple of nodes, with elements (nodes) drawn from each of the input graphs. Nodes are considered similar if their neighbors are also similar. An alternate, equivalent view of these network alignment algorithms is to consider the Kronecker product of the input graphs, and to identify high-ranked nodes in the Kronecker product graph. Conventional methods such as PageRank and HITS (Hypertext Induced Topic Selection) can be used for this purpose. These methods typically require computation of the principal eigenvector of a suitably modified Kronecker product matrix of the input graphs. We adopt this alternate view of the problem to address the problem of multiple network alignment. Using the phase estimation algorithm, we show that the multiple network alignment problem can be efficiently solved on quantum computers. We characterize the accuracy and performance of our method, and show that it can deliver exponential speedups over conventional (non-quantum) methods.

  8. Multiple network alignment on quantum computers

    NASA Astrophysics Data System (ADS)

    Daskin, Anmer; Grama, Ananth; Kais, Sabre

    2014-12-01

    Comparative analyses of graph-structured datasets underly diverse problems. Examples of these problems include identification of conserved functional components (biochemical interactions) across species, structural similarity of large biomolecules, and recurring patterns of interactions in social networks. A large class of such analyses methods quantify the topological similarity of nodes across networks. The resulting correspondence of nodes across networks, also called node alignment, can be used to identify invariant subgraphs across the input graphs. Given graphs as input, alignment algorithms use topological information to assign a similarity score to each -tuple of nodes, with elements (nodes) drawn from each of the input graphs. Nodes are considered similar if their neighbors are also similar. An alternate, equivalent view of these network alignment algorithms is to consider the Kronecker product of the input graphs and to identify high-ranked nodes in the Kronecker product graph. Conventional methods such as PageRank and HITS (Hypertext-Induced Topic Selection) can be used for this purpose. These methods typically require computation of the principal eigenvector of a suitably modified Kronecker product matrix of the input graphs. We adopt this alternate view of the problem to address the problem of multiple network alignment. Using the phase estimation algorithm, we show that the multiple network alignment problem can be efficiently solved on quantum computers. We characterize the accuracy and performance of our method and show that it can deliver exponential speedups over conventional (non-quantum) methods.

  9. Nonlocal computation in quantum cellular automata

    NASA Astrophysics Data System (ADS)

    Fussy, Siegfried; Grssing, Gerhard; Schwabl, Herbert; Scrinzi, Armin

    1993-11-01

    Quantum cellular automata (QCA) have been introduced [G. Grssing and A. Zeilinger, Complex Syst. 2, 197 (1988); 2, 611 (1988)] as n-dimensional arrays of discrete sites characterized by a complex number whose absolute square lies between 0 and 1 such that each site represents a quantum-mechanical probability amplitude. The evolutions of one-dimensional QCA with a local (i.e., nearest-neighbor) interaction and with periodic boundary conditions have been studied in some detail. In this paper we present a thorough mathematical analysis of one-dimensional QCA, and we particularly emphasize the effects of what we term nonlocal computation: because of the conservation of the total probability for each time step, information of the global array spread out over generally nonlocal distances must be conveyed for each time step to each local site via the normalization procedure. With the aid of a mathematical description of QCA evolution the following, previously observed phenomena can be explained: (i) the asymptotic appearance of plane-wave patterns after a characteristic transient phase, (ii) the dependence of the period of the patterns on the input parameters for both small and large values of the couplings between the sites, and (iii) the role of the initial values of the cells. Finally, the effects of nonlocal computation are made visible with the simulation of a ``double-slit-like'' experiment on a QCA grid.

  10. Reviews of computing technology: Client-server technology

    SciTech Connect

    Johnson, S.M.

    1990-09-01

    One of the most frequently heard terms in the computer industry these days is client-server.'' There is much misinformation available on the topic, and competitive pressures on software vendors have led to a great deal of hype with little in the way of supporting products. The purpose of this document is to explain what is meant by client-server applications, why the Advanced Technology and Architecture (ATA) section of the Information Resources Management (IRM) Department sees this emerging technology as key for computer applications during the next ten years, and what ATA sees as the existing standards and products available today. Because of the relative immaturity of existing client-server products, IRM is not yet guidelining any specific client-server products, except those that are components of guidelined data communications products or database management systems.

  11. Reviews of computing technology: Client-server technology

    SciTech Connect

    Johnson, S.M.

    1990-09-01

    One of the most frequently heard terms in the computer industry these days is ``client-server.`` There is much misinformation available on the topic, and competitive pressures on software vendors have led to a great deal of hype with little in the way of supporting products. The purpose of this document is to explain what is meant by client-server applications, why the Advanced Technology and Architecture (ATA) section of the Information Resources Management (IRM) Department sees this emerging technology as key for computer applications during the next ten years, and what ATA sees as the existing standards and products available today. Because of the relative immaturity of existing client-server products, IRM is not yet guidelining any specific client-server products, except those that are components of guidelined data communications products or database management systems.

  12. Maximizing a transport platform through computer technology.

    PubMed

    Hudson, Timothy L

    2003-01-01

    One of the most recent innovations coalescing computer technology and medical care is the further development of integrated medical component technology coupled with a computer subsystem. One such example is the self-contained patient transport system known as the Life Support for Trauma and Transport (LSTAT(tm)). The LSTAT creates a new transport platform that integrates the most current medical monitoring and therapeutic capabilities with computer processing capacity, creating the first "smart litter". The LSTAT is built around a computer system that is network capable and acts as the data hub for multiple medical devices and utilities, including data, power, and oxygen systems. The system logs patient and device data in a simultaneous, time-synchronized, continuous format, allowing electronic transmission, storage, and electronic documentation. The third-generation LSTAT includes an oxygen system, ventilator, clinical point-of-care blood analyzer, suction, defibrillator, infusion pump, and physiologic monitor, as well as on-board power and oxygen systems. The developers of LSTAT and other developers have the ability to further expand integrative component technology by developing and integrating clinical decision support systems. PMID:12802947

  13. Heterotic quantum and classical computing on convergence spaces

    NASA Astrophysics Data System (ADS)

    Patten, D. R.; Jakel, D. W.; Irwin, R. J.; Blair, H. A.

    2015-05-01

    Category-theoretic characterizations of heterotic models of computation, introduced by Stepney et al., combine computational models such as classical/quantum, digital/analog, synchronous/asynchronous, etc. to obtain increased computational power. A highly informative classical/quantum heterotic model of computation is represented by Abramsky's simple sequential imperative quantum programming language which extends the classical simple imperative programming language to encompass quantum computation. The mathematical (denotational) semantics of this classical language serves as a basic foundation upon which formal verification methods can be developed. We present a more comprehensive heterotic classical/quantum model of computation based on heterotic dynamical systems on convergence spaces. Convergence spaces subsume topological spaces but admit finer structure from which, in prior work, we obtained differential calculi in the cartesian closed category of convergence spaces allowing us to define heterotic dynamical systems, given by coupled systems of first order differential equations whose variables are functions from the reals to convergence spaces.

  14. Reviews of computing technology: Object-oriented technology

    SciTech Connect

    Skeen, D.C.

    1993-03-01

    A useful metaphor in introducing object-oriented concepts is the idea of a computer hardware manufacturer assembling products from an existing stock of electronic parts. In this analogy, think of the parts as pieces of computer software and of the finished products as computer applications. Like its counterpart, the object is capable of performing its specific function in a wide variety of different applications. The advantages to assembling hardware using a set of prebuilt parts are obvious. The design process is greatly simplified in this scenario, since the designer needs only to carry the design down to the chip level, rather than to the transistor level. As a result, the designer is free to develop a more reliable and feature rich product. Also, since the component parts are reused in several different products, the parts can be made more robust and subjected to more rigorous testing than would be economically feasible for a part used in only one piece of equipment. Additionally, maintenance on the resulting systems is simplified because of the part-level consistency from one type of equipment to another. The remainder of this document introduces the techniques used to develop objects, the benefits of the technology, outstanding issues that remain with the technology, industry direction for the technology, and the impact that object-oriented technology is likely to have on the organization. While going through this material, the reader will find it useful to remember the parts analogy and to keep in mind that the overall purpose of object-oriented technology is to create software parts and to construct applications using those parts.

  15. Is the Brain a Quantum Computer? Abninder Litta

    E-print Network

    Anderson, Charles H.

    by employing phenomena unique to quantum-level events, such as nonlocal entanglement and superpositionIs the Brain a Quantum Computer? Abninder Litta , Chris Eliasmithb,c , Frederick W. Kroona , Steven via quantum mechanical processes is irrelevant to explaining how brains produce thought, contrary

  16. Simulation of Quantum Computation: A deterministic event-based approach

    E-print Network

    K. Michielsen; K. De Raedt; H. De Raedt

    2005-01-24

    We demonstrate that locally connected networks of machines that have primitive learning capabilities can be used to perform a deterministic, event-based simulation of quantum computation. We present simulation results for basic quantum operations such as the Hadamard and the controlled-NOT gate, and for seven-qubit quantum networks that implement Shor's numbering factoring algorithm.

  17. INTRODUCTION TO QUANTUM INFORMATION AND COMPUTATION FOR CHEMISTRY

    E-print Network

    Kais, Sabre

    and analyzed these quantum effects from the view of physical chemistry for decades. Therefore, combiningINTRODUCTION TO QUANTUM INFORMATION AND COMPUTATION FOR CHEMISTRY SABRE KAIS Department. Introduction A. Qubits and Gates B. Circuits and Algorithms C. Teleportation II. Quantum Simulation A

  18. quantph/9809016 An Introduction to Quantum Computing for

    E-print Network

    Crpeau, Claude

    to give a comprehensive view of quantum mechanics as this would be beyond the scope of this paper. Our aimquantph/9809016 8 Sep 1998 An Introduction to Quantum Computing for NonPhysicists Eleanor Rieffel observed in the early 1980's [1] that certain quantum me chanical effects cannot be simulated efficiently

  19. Surface code quantum computing by lattice surgery

    E-print Network

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

    2013-02-21

    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 2-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.

  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. An Atomic Abacus: Trapped ion quantum computing experiments at NIST

    NASA Astrophysics Data System (ADS)

    Demarco, Brian

    2003-03-01

    Trapped atomic ions are an ideal system for exploring quantum information science because deterministic state preparation and efficient state detection are possible and coherent manipulation of atomic systems is relatively advanced. In our experiment, a few singly charged Be ions are confined by static and radio-frequency electric fields in a micro-machined linear Paul trap. The internal and motional states of the ions are coherently manipulated using applied laser light. Our current work focuses on demonstrating the necessary ingredients to produce a scalable quantum computing scheme and on simplifying and improving quantum logic gates. I will speak about a new set of experiments that was made possible by recent improvements in trap technology. A novel trap with multiple trapping regions was used to demonstrate the first steps towards a fully scalable quantum computing scheme. Single ions were ``shuttled" between trapping regions without disturbing the ion's motional and internal state, and two ions were separated from a single to two different trapping zones. Improvements in the trap manufacturing process has led to a reduction of nearly two orders of magnitude in the ion's motional heating rate, making possible two new improved logic gates. The first gate utilizes the wave-packet nature of the ions to tune the laser-atom interaction and achieve a controlled-NOT gate between a single ion's spin and motional states. The second, a two-ion phase gate, uses phase-space dynamics to produce a state-sensitive geometric phase. I will end with a quick look at experiments using a Mg ion to sympathetically cool a simultaneously trapped Be ion and a glimpse of the next generation of ions traps currently under construction.

  2. The QUANTGRID Project (RO)Quantum Security in GRID Computing Applications

    NASA Astrophysics Data System (ADS)

    Dima, M.; Dulea, M.; Petre, M.; Petre, C.; Mitrica, B.; Stoica, M.; Udrea, M.; Sterian, R.; Sterian, P.

    2010-01-01

    The QUANTGRID Project, financed through the National Center for Programme Management (CNMP-Romania), is the first attempt at using Quantum Crypted Communications (QCC) in large scale operations, such as GRID Computing, and conceivably in the years ahead in the banking sector and other security tight communications. In relation with the GRID activities of the Center for Computing & Communications (Nat.'l Inst. Nucl. Phys.IFIN-HH), the Quantum Optics Lab. (Nat.'l Inst. Plasma and LasersINFLPR) and the Physics Dept. (University PolytechnicaUPB) the project will build a demonstrator infrastructure for this technology. The status of the project in its incipient phase is reported, featuring tests for communications in classical security mode: socket level communications under AES (Advanced Encryption Std.), both proprietary code in C++ technology. An outline of the planned undertaking of the project is communicated, highlighting its impact in quantum physics, coherent optics and information technology.

  3. On the Security of Two Blind Quantum Computations

    E-print Network

    Shih-Min Hung; Tzonelih Hwang

    2015-08-29

    Blind quantum computation (BQC) protocol allows a client having partial quantum ability to delegate his quantum computation to a remote quantum server without leaking any information about the input, the output and the intended computation to the server. Several BQC protocols have been proposed, e.g., Li et al. in [1] proposed a triple-server BQC protocol and Xu et al. in [2] proposed a single-server BQC protocol. Though both papers claimed that their protocols can satisfy the requirement of privacy, this paper points out a security loophole in their protocols. With that the server can reveal the private information of the client.

  4. Error-rejecting quantum computing with solid state spins assisted by low-Q optical microcavities

    E-print Network

    Tao Li; Fu-Guo Deng

    2015-10-31

    We present an efficient proposal for error-rejecting quantum computing with quantum dots (QD) embedded in single-sided optical microcavities based on the interface between the circularly-polarized photon and the QDs. A unity fidelity of the quantum entangling gate (EG) can be implemented with a detectable error that leads to a recycling EG procedure, which improves further the efficiency of our proposal for EG along with robustness to the errors involved in the imperfect input-output process. Meanwhile, we discuss the performance of our proposal for EG on two solid state spins with currently achieved experiment parameters, showing that it is feasible with current experimental technology. It provides a promising building block for solid-state quantum computing and quantum networks.

  5. Gate sequence for continuous variable one-way quantum computation

    PubMed Central

    Su, Xiaolong; Hao, Shuhong; Deng, Xiaowei; Ma, Lingyu; Wang, Meihong; Jia, Xiaojun; Xie, Changde; Peng, Kunchi

    2013-01-01

    Measurement-based one-way quantum computation using cluster states as resources provides an efficient model to perform computation and information processing of quantum codes. Arbitrary Gaussian quantum computation can be implemented sufficiently by long single-mode and two-mode gate sequences. However, continuous variable gate sequences have not been realized so far due to an absence of cluster states larger than four submodes. Here we present the first continuous variable gate sequence consisting of a single-mode squeezing gate and a two-mode controlled-phase gate based on a six-mode cluster state. The quantum property of this gate sequence is confirmed by the fidelities and the quantum entanglement of two output modes, which depend on both the squeezing and controlled-phase gates. The experiment demonstrates the feasibility of implementing Gaussian quantum computation by means of accessible gate sequences.

  6. Quantum computational tensor network on string-net condensate

    NASA Astrophysics Data System (ADS)

    Morimae, Tomoyuki

    2012-06-01

    String-net condensate is a new class of materials which exhibits quantum topological order. Here we study the measurement-based quantum computation on the simplest example of string-net condensate, namely the Z2 gauge string-net condensate on the two-dimensional hexagonal lattice, by using the framework of quantum computational tensor network. We show that universal measurement-based quantum computation is possible by coupling two correlation space wires with a physical two-body interaction. We also show that universal measurement-based quantum computation is possible solely with single-qubit measurements if the sign of the coefficient of each closed-loop configuration in the state is tuned. These results suggest that even the simplest example of string-net condensate is equipped with the correlation space that has the capacity for the application to quantum information processing.

  7. Computer Education and Instructional Technology Teacher Trainees' Opinions about Cloud Computing Technology

    ERIC Educational Resources Information Center

    Karamete, Aysen

    2015-01-01

    This study aims to show the present conditions about the usage of cloud computing in the department of Computer Education and Instructional Technology (CEIT) amongst teacher trainees in School of Necatibey Education, Balikesir University, Turkey. In this study, a questionnaire with open-ended questions was used. 17 CEIT teacher trainees

  8. A Very Simple Example of Parallel Quantum Computation Frank Rioux

    E-print Network

    Rioux, Frank

    as an algorithm for the evaluation of a mathematical function, and how the same circuit is capable of parallelA Very Simple Example of Parallel Quantum Computation Frank Rioux Emeritus Professor of Chemistry CSB|SJU This tutorial deals with quantum function evaluation and parallel computation. The example

  9. Toward a Personal Quantum Computer Henry H. W. Chong

    E-print Network

    and instrumentation underlying the construction of a NMR quantum computer to facilitate the design of a desktop, and the employment of NMR to perform quantum computations is presented. Design considerations for the instrumentation-noise and radio-frequency (RF) instrumentation design needs and constraints are explained in the context

  10. The Brain Is both Neurocomputer and Quantum Computer

    ERIC Educational Resources Information Center

    Hameroff, Stuart R.

    2007-01-01

    In their article, "Is the Brain a Quantum Computer,?" Litt, Eliasmith, Kroon, Weinstein, and Thagard (2006) criticize the Penrose-Hameroff "Orch OR" quantum computational model of consciousness, arguing instead for neurocomputation as an explanation for mental phenomena. Here I clarify and defend Orch OR, show how Orch OR and neurocomputation are

  11. Technologies for Achieving Field Ubiquitous Computing

    NASA Astrophysics Data System (ADS)

    Nagashima, Akira

    Although the term ubiquitous may sound like jargon used in information appliances, ubiquitous computing is an emerging concept in industrial automation. This paper presents the author's visions of field ubiquitous computing, which is based on the novel Internet Protocol IPv6. IPv6-based instrumentation will realize the next generation manufacturing excellence. This paper focuses on the following five key issues: 1. IPv6 standardization; 2. IPv6 interfaces embedded in field devices; 3. Compatibility with FOUNDATION fieldbus; 4. Network securities for field applications; and 5. Wireless technologies to complement IP instrumentation. Furthermore, the principles of digital plant operations and ubiquitous production to support the above key technologies to achieve field ubiquitous systems are discussed.

  12. An introduction to Fault-tolerant Quantum Computing

    E-print Network

    Alexandru Paler; Simon J. Devitt

    2015-08-15

    In this paper we provide a basic introduction of the core ideas and theories surrounding fault-tolerant quantum computation. These concepts underly the theoretical framework of large-scale quantum computation and communications and are the driving force for many recent experimental efforts to construct small to medium sized arrays of controllable quantum bits. We examine the basic principals of redundant quantum encoding, required to protect quantum bits from errors generated from both imprecise control and environmental interactions and then examine the principals of fault-tolerance from largely a classical framework. As quantum fault-tolerance essentially is avoiding the uncontrollable cascade of errors caused by the interaction of quantum-bits, these concepts can be directly mapped to quantum information.

  13. Quantum optics: Cool computation, hot bits

    NASA Astrophysics Data System (ADS)

    Lloyd, Seth

    2014-02-01

    Quantum information processing provides novel methods for pumping heat and refrigerating photons. Devices that obtain and manipulate information at the quantum level can function as quantum 'Maxwell's demons' to cool systems in ways that liquid helium cannot.

  14. Effective fault-tolerant quantum computation with slow measurements

    E-print Network

    David P. DiVincenzo; Panos Aliferis

    2006-08-03

    How important is fast measurement for fault-tolerant quantum computation? Using a combination of existing and new ideas, we argue that measurement times as long as even 1,000 gate times or more have a very minimal effect on the quantum accuracy threshold. This shows that slow measurement, which appears to be unavoidable in many implementations of quantum computing, poses no essential obstacle to scalability.

  15. Scalable quantum computation via local control of only two qubits

    SciTech Connect

    Burgarth, Daniel; Maruyama, Koji; Murphy, Michael; Montangero, Simone; Calarco, Tommaso; Nori, Franco; Plenio, Martin B.

    2010-04-15

    We apply quantum control techniques to a long spin chain by acting only on two qubits at one of its ends, thereby implementing universal quantum computation by a combination of quantum gates on these qubits and indirect swap operations across the chain. It is shown that the control sequences can be computed and implemented efficiently. We discuss the application of these ideas to physical systems such as superconducting qubits in which full control of long chains is challenging.

  16. Quantum Computing and Communication 1 Paul E. Black, D. Richard Kuhn, Carl J. Williams

    E-print Network

    Black, Paul E.

    Quantum Computing and Communication 1 Paul E. Black, D. Richard Kuhn, Carl J. Williams National.williams}@nist.gov Keywords: quantum computing, error correcting codes, entanglement, superposition, quantum cryptography, quantum communication, quantum information. 6i+#...hp##3; A quantum computer, if built

  17. Quantum Computing and Communication1 Paul E. Black, D. Richard Kuhn, Carl J. Williams

    E-print Network

    Black, Paul E.

    Quantum Computing and Communication1 Paul E. Black, D. Richard Kuhn, Carl J. Williams National.williams}@nist.gov Keywords: quantum computing, error correcting codes, entanglement, superposition, quantum cryptography, quantum communication, quantum information. $EVWUDFW A quantum computer, if built, will be to an ordinary

  18. Preparing ground states of quantum many-body systems on a quantum computer

    NASA Astrophysics Data System (ADS)

    Poulin, David

    2009-03-01

    The simulation of quantum many-body systems is a notoriously hard problem in condensed matter physics, but it could easily be handled by a quantum computer [4,1]. There is however one catch: while a quantum computer can naturally implement the dynamics of a quantum system --- i.e. solve Schr"odinger's equation --- there was until now no general method to initialize the computer in a low-energy state of the simulated system. We present a quantum algorithm [5] that can prepare the ground state and thermal states of a quantum many-body system in a time proportional to the square-root of its Hilbert space dimension. This is the same scaling as required by the best known algorithm to prepare the ground state of a classical many-body system on a quantum computer [3,2]. This provides strong evidence that for a quantum computer, preparing the ground state of a quantum system is in the worst case no more difficult than preparing the ground state of a classical system. 1 D. Aharonov and A. Ta-Shma, Adiabatic quantum state generation and statistical zero knowledge, Proc. 35th Annual ACM Symp. on Theo. Comp., (2003), p. 20. F. Barahona, On the computational complexity of ising spin glass models, J. Phys. A. Math. Gen., 15 (1982), p. 3241. C. H. Bennett, E. Bernstein, G. Brassard, and U. Vazirani, Strengths and weaknessess of quantum computing, SIAM J. Comput., 26 (1997), pp. 1510--1523, quant-ph/9701001. S. Lloyd, Universal quantum simulators, Science, 273 (1996), pp. 1073--1078. D. Poulin and P. Wocjan, Preparing ground states of quantum many-body systems on a quantum computer, 2008, arXiv:0809.2705.

  19. Columbia Optics and Quantum Electronics "Nanophotonic Technologies for Quantum Optics and Metrology"

    E-print Network

    Polvani, Lorenzo M.

    and metrology. In the first part of this talk, I will describe our efforts to develop quantum light sourcesColumbia Optics and Quantum Electronics Seminar "Nanophotonic Technologies for Quantum Optics and Metrology" Date/Time: January 30th (Monday), 11 am to 12 noon Location: 7th floor Interschool Laboratory

  20. An introduction to many worlds in quantum computation

    E-print Network

    Clare Hewitt-Horsman

    2009-07-08

    The interpretation of quantum mechanics is an area of increasing interest to many working physicists. In particular, interest has come from those involved in quantum computing and information theory, as there has always been a strong foundational element in this field. This paper introduces one interpretation of quantum mechanics, a modern `many-worlds' theory, from the perspective of quantum computation. Reasons for seeking to interpret quantum mechanics are discussed, then the specific `neo-Everettian' theory is introduced and its claim as the best available interpretation defended. The main objections to the interpretation, including the so-called ``problem of probability'' are shown to fail. The local nature of the interpretation is demonstrated, and the implications of this both for the interpretation and for quantum mechanics more generally are discussed. Finally, the consequences of the theory for quantum computation are investigated, and common objections to using many worlds to describe quantum computing are answered. We find that using this particular many-worlds theory as a physical foundation for quantum computation gives several distinct advantages over other interpretations, and over not interpreting quantum theory at all.