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1

Centre for Quantum Computation & Communication Technology

NSDL National Science Digital Library

This is the homepage of "an Australian multi-university collaboration undertaking research on the fundamental physics and technology of building, at the atomic level, a solid state quantum computer in silicon together with other high potential implementations." Although attempts to develop a quantum computer have met with limited success, the centre has substantial resources invested in advancing toward practical uses of quantum computing technology. The site provides a very good introduction to the principles and implications of quantum computing, as well as details about various research projects underway at the Australian universities. Links to conference and journal papers produced by members of the centre, many from 2003, are also provided.

2

An Overview of Quantum Computing for Technology Managers

Faster algorithms, novel cryptographic mechanisms, and alternative methods of communication become possible when the model underlying information and computation changes from a classical mechanical model to a quantum mechanical one. Quantum algorithms perform a select set of tasks vastly more efficiently than any classical algorithm, but for many tasks it has been proved that quantum algorithms provide no advantage. The breadth of quantum computing applications is still being explored. Major application areas include security and the many fields that would benefit from efficient quantum simulation. The quantum information processing viewpoint provides insight into classical algorithmic issues as well as a deeper understanding of entanglement and other non-classical aspects of quantum physics. This overview is aimed at technology managers who wish to gain a high level understanding of quantum information processing, particularly quantum computing.

Eleanor G. Rieffel

2008-09-26

3

Quantum computing is a quickly growing research field. This article introduces the basic concepts of quantum computing, recent developments in quantum searching, and decoherence in a possible quantum dot realization. PMID:11562459

Li, Shu-Shen; Long, Gui-Lu; Bai, Feng-Shan; Feng, Song-Lin; Zheng, Hou-Zhi

2001-01-01

4

The remarkable developments in theoretical and experimental quantum computation that have been inspired by Feynman's seminal papers on the subject are reviewed. Following an introduction to quantum computation, the implications for cryptography of quantum factoring are discussed. The requirements and challenges for practical quantum computational hardware are illustrated with an overview of the ion trap quantum computation project at Los

Richard J. Hughes

2001-01-01

5

QUANTUM CRYPTOGRAPHY QUANTUM COMPUTING

QUANTUM CRYPTOGRAPHY QUANTUM COMPUTING 1. Quantum cryptography : from basic principles to practical'Optique, Orsay #12;QIPC / S4P QUANTUM CRYPTOGRAPHY A. Beveratos1, A. Villing1, F. Grosshans1, J. Wenger1, T principles of quantum key distribution (quantum cryptography)(quantum cryptography) 2. Quantum key

Bachoc, Christine

6

Quantum technology for aerospace applications

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

7

Quantum computing is at the forefront of scientific and technological research and development of the 21st century. NMR quantum\\u000a computing is one the most mature technologies for implementing quantum computation. It utilizes the motion of spins of nuclei\\u000a in custom-designed molecules manipulated by RF pulses. The motion is on a nano- or microscopic scale governed by the Schr¨odinger\\u000a equation in

Zhigang Zhang; Goong Chen; Zijian Diao; Philip R. Hemmer

8

Quantum computing with trapped ions

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.

Hughes, R.J.

1998-01-01

9

NSDL National Science Digital Library

Students will learn the history of computers as well as how computers work. COMPUTER TECHNOLOGY (9-12) - 52.0417 Computer Technology is an introduction to computer application software that includes word processing, spreadsheet, database, and telecommunications. An awareness of career opportunities, business ethics, and trends is included. Everything is done with computers. Your job will most likely have a computer to save files, write ...

Mrs. Thackeray

2007-10-14

10

Quantum Information Technology

NSDL National Science Digital Library

From the research laboratories of Hewlett Packard, Quantum Information Technology provides an informative look at current work in quantum information processing and communication (QIPC). The report, published in November 2002, recognizes the potential applications of QIPC and how it could revolutionize conventional information technology. It cites cryptography, quantum computers, and quantum teleportation as motivational factors for development of this technology, offering a basic introduction to each discipline. The paper concludes with an analysis of the direction current research is taking and what the future may hold. Several links to further sources of information are also included.

Spiller, Timothy.

2002-01-01

11

Quantum Computers and Quantum Control

Quantum computation is an excercise in quantum control: for a quantum system to compute, its dynamics must be controlled to a high degree of precision. Quantum control, in turn, is an excercise in quantum computation: control can be thought of in terms of how information is represented and processed. This talk reviews recent developments in quantum computation and quantum control

Seth Lloyd

2001-01-01

12

The first quantum technology, which harnesses uniquely quantum mechanical effects for its core operation, has arrived in the form of commercially available quantum key distribution systems that achieve enhanced security by encoding information in photons such that information gained by an eavesdropper can be detected. Anticipated future quantum technologies include large-scale secure networks, enhanced measurement and lithography, and quantum information processors, promising exponentially greater computation power for particular tasks. Photonics is destined for a central role in such technologies owing to the need for high-speed transmission and the outstanding low-noise properties of photons. These technologies may use single photons or quantum states of bright laser beams, or both, and will undoubtably apply and drive state-of-the-art developments in photonics.

Jeremy L. O'Brien; Akira Furusawa; Jelena Vu?kovi?

2010-03-20

13

Quantum Chaos and Quantum Computers

The standard generic quantum computer model is studied analytically and numerically and the border for emergence of quantum chaos, induced by imperfections and residual inter-qubit couplings, is determined. This phenomenon appears in an isolated quantum computer without any external decoherence. The onset of quantum chaos leads to quantum computer hardware melting, strong quantum entropy growth and destruction of computer operability.

D. L. Shepelyansky

2001-01-01

14

Quantum chaos and quantum computers

The standard generic quantum computer model is studied analytically and numerically and the border for emergence of quantum chaos, induced by imperfections and residual inter-qubit couplings, is determined. This phenomenon appears in an isolated quantum computer without any external decoherence. The onset of quantum chaos leads to quantum computer hardware melting, strong quantum entropy growth and destruction of computer operability.

D. L. Shepelyansky

2001-01-01

15

Fault-tolerant quantum computation

The discovery of quantum error correction has greatly improved the long-term prospects for quantum computing technology. Encoded quantum information can be protected from errors that arise due to uncontrolled interactions with the environment, or due to imperfect implementations of quantum logical operations. Recovery from errors can work effectively even if occasional mistakes occur during the recovery procedure. Furthermore, encoded quantum

John Preskill

1997-01-01

16

Quantum Computers and Quantum Control

NASA Astrophysics Data System (ADS)

Quantum computation is an excercise in quantum control: for a quantum system to compute, its dynamics must be controlled to a high degree of precision. Quantum control, in turn, is an excercise in quantum computation: control can be thought of in terms of how information is represented and processed. This talk reviews recent developments in quantum computation and quantum control with an emphasis on their theoretical and experimental overlap.

Lloyd, Seth

2001-03-01

17

Quantum Computing, Metrology, and Imaging

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.

Hwang Lee; Pavel Lougovski; Jonathan P. Dowling

2005-06-17

18

NASA Astrophysics Data System (ADS)

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.

Kendon, Viv

2014-12-01

19

Cryptography, quantum computation and trapped ions

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.

R. J. Hughes; Richard J

1998-01-01

20

Cryptography, quantum computation and trapped ions

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.

Hughes, Richard J.

1998-03-01

21

Quantum Computation via Paraconsistent Computation

We present an original model of paraconsistent Turing machines (PTMs), a generalization of the classical Turing machines model of computation using a paraconsistent logic. Next, we briefl y describe the standard models of quantum computation: quantum Turing machines and quantum circuits, and revise quantum algorithms to solve the so-called Deutsch's problem and Deutsch-Jozsa problem. Then, we show the potentialities of

Juan C. Agudelo; Walter Carnielli

2006-01-01

22

We describe a quantum computer emulator for a generic, general purpose quantum computer. This emulator consists of a simulator of the physical realization of the quantum computer and a graphical user interface to program and control the simulator. We illustrate the use of the quantum computer emulator through various implementations of the Deutsch-Jozsa and Grover's database search algorithm.

Hans De Raedt; Anthony Hams; Kristel Michielsen; Koen De Raedt

1999-11-09

23

Quantum Computer Games: Quantum Minesweeper

ERIC Educational Resources Information Center

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…

Gordon, Michal; Gordon, Goren

2010-01-01

24

Quantum Logic and Quantum Computation

We use classes of Hilbert lattice equations for an alternative representation of Hilbert lattices and Hilbert spaces of arbitrary quantum systems that might enable a direct introduction of the states of the systems into quantum computers. More specifically, we look for a way to feed a quantum computer with algebraic equations of n-th order underlying an infinite dimensional Hilbert space

Mladen Pavicic; Norman D. Megill

2008-01-01

25

NASA Astrophysics Data System (ADS)

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.

Landahl, Andrew

2012-10-01

26

Quantum computing and communication

A quantum computer, if built, will be to an ordinary computer as a hydrogen bomb is to gunpowder, at least for some types of computations. Today no quantum computer exists, beyond laboratory prototypes capable of solving only tiny problems, and many practical problems remain to be solved. Yet the theory of quantum computing has advanced significantly in the past decade,

Paul E. Black; D. Richard Kuhn; Carl J. Williams

2002-01-01

27

Both DNA and quantum computers have the potential to exceed the power of con- ventional digital computers, though substan- tial technical difficulties first must be over- come. Through coherent superposition of states, quantum computers are more pow- erful than classical Turing machines. DNA computers are evolvable through biotechnol- ogy techniques. By combining DNA and quantum computers, both of these charac-

Russell Deaton

28

Quantum robots and quantum computers

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.

Benioff, P.

1998-07-01

29

Quantum Computation as Geometry

Quantum computers hold great promise, but it remains a challenge to find efficient quantum circuits that solve interesting computational problems. We show that finding optimal quantum circuits is essentially equivalent to finding the shortest path between two points in a certain curved geometry. By recasting the problem of finding quantum circuits as a geometric problem, we open up the possibility of using the mathematical techniques of Riemannian geometry to suggest new quantum algorithms, or to prove limitations on the power of quantum computers.

Michael A. Nielsen; Mark R. Dowling; Mile Gu; Andrew C. Doherty

2006-03-19

30

Generalized GHZ States and Distributed Quantum Computing

A key problem in quantum computing is finding a viable technological path toward the creation of a scalable quantum computer. One possible approach toward solving part of this problem is distributed computing, which provides an effective way of utilizing a network of limited capacity quantum computers. In this paper, we present two primitive operations, cat-entangler and cat-disentangler, which in turn

Anocha Yimsiriwattana; Samuel J. Lomonaco Jr

2004-01-01

31

Optimal Blind Quantum Computation

NASA Astrophysics Data System (ADS)

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 concrete bounds for common choices of the client’s quantum capabilities. Our results show that the universal blind quantum computation protocol of Broadbent, Fitzsimons, and Kashefi, 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.

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

2013-12-01

32

Quantum information technology

A new quantum information technology (QIT) could emerge in the future, based on current research in the fields of quantum information processing and communication1–3 (QIPC). In contrast to conventional IT, where quantum mechanics plays a support role in improving the building blocks, fundamental quantum phenomena play a central role in QIPC — information is stored, processed, and communicated according to

Timothy P. Spiller

2003-01-01

33

QUANTUM COMPUTATION AND INFORMATION

- tum computation and information was accelerated in several fronts: hardware for quantum computationQUANTUM COMPUTATION AND INFORMATION AmÂ´ilcar Sernadas,1 Paulo Mateus1 and Yasser Omar2 1CLC, Dep After a very brief survey of the key milestones and open problems in quantum computation and information

Lisboa, Universidade TÃ©cnica de

34

Quantum Computation and Quantum Spin Dynamics

We analyze the stability of quantum computations on physically realizable quantum computers by simulating quantum spin models representing quantum computer hardware. Examples of logically identical implementations of the controlled-NOT operation 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

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

2001-01-01

35

Quantum Computers as Fuzzy Computers

An implementation of digitised fuzzy numbers on quantum computers is suggested. It is shown that due to the famous quantum\\u000a parallelism quantum computers can operate “globally”on whole membership functions of fuzzy numbers,not by calculating them\\u000a “point by point” as classical computers do, which leads to the considerable decrease in the number of operations involved\\u000a in storing and calculating fuzzy numbers.

Jaroslaw Pykacz; Bart D’Hooghe; Roman R. Zapatrin

2001-01-01

36

Instrumentation for quantum computers

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 ...

Huang, Wei-Han, 1979-

2004-01-01

37

The manuscript poses and addresses a new very fundamental issue in Quantum Computer Science, which is going to have a radical impact on the way we currently conceive quantum computation. We show that there exists a new kind of \\

G. Chiribella; G. M. D'Ariano; P. Perinotti; B. Valiron

2009-01-01

38

Cryptography, Quantum Computation and Trapped Ions

The significance of quantum computation for cryptography is discussed.\\u000aFollowing a brief survey of the requirements for quantum computational\\u000ahardware, an overview of the ion trap quantum computation project at Los Alamos\\u000ais presented. The physical limitations to quantum computation with trapped ions\\u000aare analyzed and an assessment of the computational potential of the technology\\u000ais made.

Richard J. Hughes

1997-01-01

39

Towards quantum chemistry on a quantum computer.

Exact first-principles calculations of molecular properties are currently intractable because their computational cost grows exponentially with both the number of atoms and basis set size. A solution is to move to a radically different model of computing by building a quantum computer, which is a device that uses quantum systems themselves to store and process data. Here we report the application of the latest photonic quantum computer technology to calculate properties of the smallest molecular system: the hydrogen molecule in a minimal basis. We calculate the complete energy spectrum to 20 bits of precision and discuss how the technique can be expanded to solve large-scale chemical problems that lie beyond the reach of modern supercomputers. These results represent an early practical step toward a powerful tool with a broad range of quantum-chemical applications. PMID:21124400

Lanyon, B P; Whitfield, J D; Gillett, G G; Goggin, M E; Almeida, M P; Kassal, I; Biamonte, J D; Mohseni, M; Powell, B J; Barbieri, M; Aspuru-Guzik, A; White, A G

2010-02-01

40

Introduction to the World of Quantum Computers

The world is changing very fast, and so are the ways of communication and computation. This article is about a new communication and information technology based on the principles of the quantum physics. At first we discuss about some fundamental paradigms of Quantum Computers World, and then introducing the basis of quantum computation: \\

Sina Jafarpour

2006-01-01

41

Quantum Technology: The Second Quantum Revolution

We are currently in the midst of a second quantum revolution. The first quantum revolution gave us new rules that govern physical reality. The second quantum revolution will take these rules and use them to develop new technologies. In this review we discuss the principles upon which quantum technology is based and the tools required to develop it. We discuss a number of examples of research programs that could deliver quantum technologies in coming decades including; quantum information technology, quantum electromechanical systems, coherent quantum electronics, quantum optics and coherent matter technology.

Jonathan P. Dowling; Gerard J. Milburn

2002-06-13

42

Quantum Computation 6.1 Introduction of quantum computation

behavior of quantum computer hardware [121]. The contents of this chapter are organized as following83 Chapter 6 Quantum Computation 6.1 Introduction of quantum computation Quantum computation of quantum physics. The basic ideas of quantum computation emerged when scientists were con- templating

43

Secure assisted quantum computation

Suppose Alice wants to perform some computation that could be done quickly on\\u000aa quantum computer, but she cannot do universal quantum computation. Bob can do\\u000auniversal quantum computation and claims he is willing to help, but Alice wants\\u000ato be sure that Bob cannot learn her input, the result of her calculation, or\\u000aperhaps even the function she is

Andrew M. Childs

2001-01-01

44

We propose a fluxon-controlled quantum computer incorporated with three-qubit quantum error correction using special gate operations, i.e., joint-phase and SWAP gate operations, inherent in capacitively coupled superconducting flux qubits. The proposed quantum computer acts exactly like a knitting machine at home.

Toshiyuki Fujii; Shigemasa Matsuo; Noriyuki Hatakenaka

2009-05-14

45

We propose a fluxon-controlled quantum computer incorporated with three-qubit quantum error correction using special gate operations, i.e., joint-phase and SWAP gate operations, inherent in capacitively coupled superconducting flux qubits. The proposed quantum computer acts exactly like a knitting machine at home.

Fujii, Toshiyuki; Hatakenaka, Noriyuki

2009-01-01

46

Physics 219: Quantum Computation

NSDL National Science Digital Library

This is the course web page for an undergraduate Quantum Computation course at Caltech. A course outline, extensive lecture notes, and homework sets, some with solutions, are provided. Links to recent versions of the course are included. There are also links to important references and other web resources in quantum information theory and quantum computation.

Preskill, John

2005-04-16

47

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 extremum of a function, an image, a solution to a system of ODE, or a stochastic process. In this paper, a quantum version of recurrent neural

Michail Zak

1999-01-01

48

COMPUTER SCIENCE INFORMATION TECHNOLOGY

COMPUTER SCIENCE and INFORMATION TECHNOLOGY POSTGRADUATE STUDIES 2006 School of Mathematics of Information Systems with Honours Master of Science (Computer Science) Professional Doctorate in Science (Computer Science) PhD (Computer Science) The postgraduate programs in Computer Science and Information

Dunstan, Neil

49

Quantum Computing since Democritus

NASA Astrophysics Data System (ADS)

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

Aaronson, Scott

2013-03-01

50

Scalable optical quantum computer

NASA Astrophysics Data System (ADS)

A way of designing a scalable optical quantum computer based on the photon echo effect is proposed. Individual rare earth ions Pr3+, regularly located in the lattice of the orthosilicate (Y2SiO5) 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.

Manykin, E. A.; Mel'nichenko, E. V.

2014-12-01

51

Physical Models for Quantum Computers

We discuss the impact of the physical implementation of a quantum computer on its computational efficiency, using computer simulations of physical models of quantum computer hardware. We address the computational efficiency of practical procedures to extract the results of a quantum computation from the wave function respresenting the final state of the quantum computer.

H. De Raedt; K. Michielsen; S. Miyashita; K. Saito

2002-01-01

52

Towards Quantum Chemistry on a Quantum Computer

The fundamental problem faced in quantum chemistry is the calculation of molecular properties, which are of practical importance in fields ranging from materials science to biochemistry. Within chemical precision, the total energy of a molecule as well as most other properties, can be calculated by solving the Schrodinger equation. However, the computational resources required to obtain exact solutions on a conventional computer generally increase exponentially with the number of atoms involved. This renders such calculations intractable for all but the smallest of systems. Recently, an efficient algorithm has been proposed enabling a quantum computer to overcome this problem by achieving only a polynomial resource scaling with system size. Such a tool would therefore provide an extremely powerful tool for new science and technology. Here we present a photonic implementation for the smallest problem: obtaining the energies of H2, the hydrogen molecule in a minimal basis. We perform a key algorithmic step - the iterative phase estimation algorithm - in full, achieving a high level of precision and robustness to error. We implement other algorithmic steps with assistance from a classical computer and explain how this non-scalable approach could be avoided. Finally, we provide new theoretical results which lay the foundations for the next generation of simulation experiments using quantum computers. We have made early experimental progress towards the long-term goal of exploiting quantum information to speed up quantum chemistry calculations.

Benjamin P. Lanyon; James D. Whitfield; Geoff G. Gillet; Michael E. Goggin; Marcelo P. Almeida; Ivan Kassal; Jacob D. Biamonte; Masoud Mohseni; Ben J. Powell; Marco Barbieri; Alán Aspuru-Guzik; Andrew G. White

2009-05-08

53

Quantum computing with trapped ions

Quantum computers hold the promise of solving certain computational tasks much more efficiently than classical computers. We review recent experimental advances towards a quantum computer with trapped ions. In particular, various implementations of qubits, quantum gates and some key experiments are discussed. Furthermore, we review some implementations of quantum algorithms such as a deterministic teleportation of quantum information and an

H. Häffner; C. F. Roos; R. Blatt

2008-01-01

54

Quantum computing: pro and con

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 nding 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

Charles C. Lauritsen

55

Quantum computing: pro and con

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

John Preskill

1998-01-01

56

Quantum Computation: A Computer Science Perspective

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

Anders K. H. Bengtsson

2005-01-01

57

Simulation of Quantum Computers

The steady process of computer miniaturisation will soon come to a scale where quantum eects on computation can no longer be ignored. Hardware development will Þnally reach a point where boolean logic will no longer be applicable and the classical concept of a universal deterministic computer with the Turing machine as mathematical model will have to be replaced by a

Karl Svozil

58

Modelling of Miniature Ion Traps for Quantum Computing

Ion traps are one of the leading technologies for the implementation of quantum computers in hardware. They are a vacuum technology that captures small number of laser-cooled ions in a linear trap and uses their quantum states to construct quantum circuits. We present the simulation results for quantum computing in a miniature ion trap in order to investigate electrostatics, ion

Boris Brkic´; Elias J. Griffith; Stephen Taylor; Jason F. Ralph

2004-01-01

59

Quantum Computing and Digital Computing

Electronic systems that contain a large number of solid-state devices must deal with the fact that there are likely to be differences between nominally identical components. Methods for manufacturing solid-state devices do not produce highly reproducible products, and solid-state devices change with age and use. Quantum computing systems propose to use the same binary digital language to represent information and

Robert W. Keyes

2010-01-01

60

Geometric methods in quantum computation

Recent advances in the physical sciences and engineering have created great hopes for new computational paradigms and substrates. One such new approach is the quantum computer, which holds the promise of enhanced computational power. Analogous to the way a classical computer is built from electrical circuits containing wires and logic gates, a quantum computer is built from quantum circuits containing

Jun Zhang

2003-01-01

61

Fault-Tolerant Quantum Computation

It has recently been realized that use of the properties of quantum mechanics might speed up certain compu- tations dramatically. Interest in quantum computation has since been growing. One of the main difficulties in realizing quantum computation is that decoherence tends to destroy the information in a superposition of states in a quantum computer, making long compu- tations impossible. A

Peter W. Shor

1996-01-01

62

Layered architecture for quantum computing

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 coherent 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

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

2010-01-01

63

Mathematical Models of Quantum Computation

In this paper, we introduce two mathematical models of realistic quantum computation. First, we develop a theory of bulk quantum\\u000a computation such as NMR (Nuclear Magnetic Resonance) quantum computation. For this purpose, we define bulk quantum Turing\\u000a machine (BQTM for short) as a model of bulk quantum computation. Then, we define complexity classes EBQP, BBQP and ZBQP as\\u000a counterparts of

Tetsuro Nishino

2002-01-01

64

Blind topological measurement-based quantum computation

NASA Astrophysics Data System (ADS)

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

Morimae, Tomoyuki; Fujii, Keisuke

2012-09-01

65

Blind topological measurement-based quantum computation

Blind quantum computation is a novel secure quantum-computing protocol that enables Alice, who does not have sufficient quantum technology at her disposal, to delegate her quantum computation to Bob, who has a fully fledged quantum computer, in such a way that Bob cannot learn anything about Alice's input, output and algorithm. A recent proof-of-principle experiment demonstrating blind quantum computation in an optical system has raised new challenges regarding the scalability of blind quantum computation in realistic noisy conditions. Here we show that fault-tolerant blind quantum computation is possible in a topologically protected manner using the Raussendorf–Harrington–Goyal scheme. The error threshold of our scheme is 4.3×10?3, which is comparable to that (7.5×10?3) of non-blind topological quantum computation. As the error per gate of the order 10?3 was already achieved in some experimental systems, our result implies that secure cloud quantum computation is within reach. PMID:22948818

Morimae, Tomoyuki; Fujii, Keisuke

2012-01-01

66

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

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.

Paola Zizzi

2009-05-28

67

We propose a (theoretical) model for quantum computation where the result can be read out from the time average of the Hamiltonian dynamics of a 2-dimensional crystal on a cylinder.The Hamiltonian is a spatially local interaction among Wigner–Seitz cells containing six qubits. The quantum circuit that is simulated is specified by the initialization of program qubits. As in Margolus’ Hamiltonian

Dominik Janzing; Pawel Wocjan

2005-01-01

68

Concurrent Quantum Computation

A quantum computer is a multi-particle interferometer that comprises beam splitters at both ends and arms, where the n two-level particles undergo the interactions among them. The arms are designed so that relevant functions required to produce a computational result is stored in the phase shifts of the 2^n arms. They can be detected by interferometry that allows us to utilize quantum parallelism. Quantum algorithms are accountable for what interferometers to be constructed to compute particular problems. A standard formalism for constructing the arms has been developed by the extension of classical reversible gate arrays. By its nature of sequential applications of logic operations, the required number of gates increases exponentially as the problem size grows. This may cause a crucial obstacle to perform a quantum computation within a limited decoherence time. We propose a direct and concurrent construction of the interferometer arms by one-time evolution of a physical system with arbitrary multi-particle interactions. It is inherently quantum mechanical and has no classical analogue. Encoding the functions used in Shor's algorithm for prime factoring, Grover's algorithm and Deutsch-Jozsa algorithm requires only one-time evolution of such a system regardless of the problem size n as opposed to its standard sequential counterpart that takes O(n^3), O(n) and O(n2^n).

F. Yamaguchi; C. P. Master; Y. Yamamoto

2000-05-31

69

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

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.

Gheorghiu, Vlad

2014-01-01

70

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

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.

Vlad Gheorghiu

2014-12-15

71

Computational quantum chemistry website

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.

none,

1997-08-22

72

Some Thoughts Regarding Practical Quantum Computing

NASA Astrophysics Data System (ADS)

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.

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

2006-03-01

73

Quantum Computation: A Computer Science Perspective

The theory of quantum computation is presented in a self contained way from a\\u000acomputer science perspective. The basics of classical computation and quantum\\u000amechanics is reviewed. The circuit model of quantum computation is presented in\\u000adetail. Throughout there is an emphasis on the physical as well as the abstract\\u000aaspects of computation and the interplay between them.\\u000a This report

Anders K. H. Bengtsson

2005-01-01

74

Genetic Algorithms and Quantum Computation

Recently, researchers have applied genetic algorithms (GAs) to address some problems in quantum computation. Also, there has been some works in the designing of genetic algorithms based on quantum theoretical concepts and techniques. The so called Quantum Evolutionary Programming has two major sub-areas: Quantum Inspired Genetic Algorithms (QIGAs) and Quantum Genetic Algorithms (QGAs). The former adopts qubit chromosomes as representations

Gilson A. Giraldi; Renato Portugal; Ricardo N. Thess

2004-01-01

75

Quantum computation Samuel L. Braunstein

gates for quantum bits 6. Logic gates in the laboratory 7. Model quantum computer and quantum code 8 an elementary quantum mechanical ex- periment [9]. The two-slit experiment is prototypic for observing one key feature of quantum mechanicals: A source emits photons, electrons or other particles that arrive at a pair

Braunstein, Samuel L.

76

Triple-server blind quantum computation using entanglement swapping

NASA Astrophysics Data System (ADS)

Blind quantum computation allows a client who does not have enough quantum resources or technologies to achieve quantum computation on a remote quantum server such that the client's input, output, and algorithm remain unknown to the server. Up to now, single- and double-server blind quantum computation have been considered. In this work, we propose a triple-server blind computation protocol where the client can delegate quantum computation to three quantum servers by the use of entanglement swapping. Furthermore, the three quantum servers can communicate with each other and the client is almost classical since one does not require any quantum computational power, quantum memory, and the ability to prepare any quantum states and only needs to be capable of getting access to quantum channels.

Li, Qin; Chan, Wai Hong; Wu, Chunhui; Wen, Zhonghua

2014-04-01

77

From the Academy Quantum computing

in a possible quantum dot realization. Quantum computing combines computer science with quan- tum mechanicsFrom the Academy Quantum computing Shu-Shen Li* , Gui-Lu LongÂ§Â¶ , Feng-Shan Bai , Song-Lin Feng*, and Hou-Zhi Zheng* *National Laboratory for Superlattices and Microstructures, Institute of Semiconductors

Bai, Fengshan

78

Quantum Computation and Spin Manipulation

1 Quantum Computation and Spin Manipulation 0Anthony Hams #12;Quantum Computation and Spin Manipulation Anthony Hams #12;To my grandfathers The work described in this thesis was performed at the Centre, Nijenborgh 4, 9747 AG Groningen, The Netherlands. Anthony Hams Quantum Computation and Spin Manipulation

79

Abstract Emulation of Quantum Computing

Quantum computers realize parallel computing and solve NP problems efficiently since the possibilities of all the candidates for the answer are simultaneously calculated by utilizing quantum-mechanical processes. NP problems such as factorization are problems for which it is difficult to find the answers but candidates found are easily verified. In order to realize a quantum computer for solving practical problems,

Minoru Fujishima; Koichiro Hoh

80

Database Manipulation on Quantum Computers

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,

Ahmed Younes

2007-01-01

81

Holographic quantum computing.

We propose to use a single mesoscopic ensemble of trapped polar molecules for quantum computing. A "holographic quantum register" with hundreds of qubits is encoded in collective excitations with definite spatial phase variations. Each phase pattern is uniquely addressed by optical Raman processes with classical optical fields, while one- and two-qubit gates and qubit readout are accomplished by transferring the qubit states to a stripline microwave cavity field and a Cooper pair box where controllable two-level unitary dynamics and detection is governed by classical microwave fields. PMID:18764313

Tordrup, Karl; Negretti, Antonio; Mølmer, Klaus

2008-07-25

82

Relativistic quantum chemistry on quantum computers

Last years witnessed a remarkable interest in application of quantum computing for solving problems in quantum chemistry more efficiently than classical computers allow. Very recently, even first proof-of-principle experimental realizations have been reported. However, so far only the non-relativistic regime (i.e. Schroedinger equation) has been explored, while it is well known that relativistic effects can be very important in chemistry. In this letter we present the first quantum algorithm for relativistic computations of molecular energies. We show how to efficiently solve the eigenproblem of the Dirac-Coulomb Hamiltonian on a quantum computer and demonstrate the functionality of the proposed procedure by numerical simulations of computations of the spin-orbit splitting in the SbH molecule. Finally, we propose quantum circuits with 3 qubits and 9 or 10 CNOTs, which implement a proof-of-principle relativistic quantum chemical calculation for this molecule and might be suitable for an experimental realization.

Libor Veis; Jakub Viš?ák; Timo Fleig; Stefan Knecht; Trond Saue; Lucas Visscher; Ji?í Pittner

2012-03-26

83

Layered Architecture for Quantum Computing

NASA Astrophysics Data System (ADS)

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 time scales 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 time scale of days.

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

2012-07-01

84

Layered architecture for quantum computing

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.

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

2010-10-24

85

Computational structures technology

NASA Technical Reports Server (NTRS)

Computational structures technology (CST), which has emerged from FEM developments, is a fusion of materials modeling, structural and dynamic analysis and synthesis methods, on the one hand, and numerical analysis and approximation theory, on the other. In addition to computational materials modeling, CST encompasses computational methods for predicting the response, performance, failure, and service life of structures and their components, as well as automated methods for structural synthesis and optimization.

Noor, Ahmed K.

1992-01-01

86

A Theory of Physical Quantum Computation: The Quantum Computer Condition

In this paper we present a new unified theoretical framework that describes the full dynamics of quantum computation. Our formulation allows any questions pertaining to the physical behavior of a quantum computer to be framed, and in principle, answered. We refer to the central organizing principle developed in this paper, on which our theoretical structure is based, as the *Quantum

Gerald Gilbert; Michael Hamrick; F. Javier Thayer

2005-01-01

87

Topological quantum computation

The theory of quantum computation can be constructed from the abstract study\\u000aof anyonic systems. In mathematical terms, these are unitary topological\\u000amodular functors. They underlie the Jones polynomial and arise in\\u000aWitten-Chern-Simons theory. The braiding and fusion of anyonic excitations in\\u000aquantum Hall electron liquids and 2D-magnets are modeled by modular functors,\\u000aopening a new possibility for the realization

Michael H. Freedman; Alexei Kitaev; Michael J. Larsen; Zhenghan Wang; L. D. Landau; Michael H. Freedman

2002-01-01

88

Computer Technology for Industry

NASA Technical Reports Server (NTRS)

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.

1979-01-01

89

Simulating quantum systems on a quantum computer

We show that the time evolution of the wave function of a quantum mechanical many particle system can be implemented very efficiently on a quantum computer. The computational cost of such a simulation is comparable to the cost of a conventional simulation of the corresponding classical system. We then sketch how results of interest, like the energy spectrum of a

C. Zalka

1998-01-01

90

Quantum computing on encrypted data

NASA Astrophysics Data System (ADS)

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.

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

2014-01-01

91

Measurement-based quantum computation

Quantum computation offers a promising new kind of information processing, where the non-classical features of quantum mechanics are harnessed and exploited. A number of models of quantum computation exist. These models have been shown to be formally equivalent, but their underlying elementary concepts and the requirements for their practical realization can differ significantly. A particularly exciting paradigm is that of

D. E. Browne; R. Raussendorf; M. Van den Nest; H. J. Briegel

2009-01-01

92

Quantum Computation Using Optically Coupled Quantum Dot Arrays

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

93

Quantum Computation Toward Quantum Gravity

NASA Astrophysics Data System (ADS)

The aim of this paper is to enlighten the emerging relevance of Quantum Information Theory in the field of Quantum Gravity. As it was suggested by J. A. Wheeler, information theory must play a relevant role in understanding the foundations of Quantum Mechanics (the "It from bit" proposal). Here we suggest that quantum information must play a relevant role in Quantum Gravity (the "It from qubit" proposal). The conjecture is that Quantum Gravity, the theory which will reconcile Quantum Mechanics with General Relativity, can be formulated in terms of quantum bits of information (qubits) stored in space at the Planck scale. This conjecture is based on the following arguments: a) The holographic principle, b) The loop quantum gravity approach and spin networks, c) Quantum geometry and black hole entropy. From the above arguments, as they stand in the literature, it follows that the edges of spin networks pierce the black hole horizon and excite curvature degrees of freedom on the surface. These excitations are micro-states of Chern-Simons theory and account of the black hole entropy which turns out to be a quarter of the area of the horizon, (in units of Planck area), in accordance with the holographic principle. Moreover, the states which dominate the counting correspond to punctures of spin j = 1/2 and one can in fact visualize each micro-state as a bit of information. The obvious generalization of this result is to consider open spin networks with edges labeled by the spin -1/ 2 representation of SU(2) in a superposed state of spin "on" and spin "down." The micro-state corresponding to such a puncture will be a pixel of area which is "on" and "off" at the same time, and it will encode a qubit of information. This picture, when applied to quantum cosmology, describes an early inflationary universe which is a discrete version of the de Sitter universe.

Zizzi, P. A.

2001-08-01

94

Quantum computing with defects.

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

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

2010-05-11

95

Self-correcting quantum computers

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 ...

Chhajlany, R W

96

Software Pauli Tracking for Quantum Computation

The realisation of large-scale quantum computing is no longer simply a hardware question. The rapid development of quantum technology has resulted in dozens of control and programming problems that should be directed towards the classical computer science and engineering community. One such problem is known as Pauli tracking. Methods for implementing quantum algorithms that are compatible with crucial error correction technology utilise extensive quantum teleportation protocols. These protocols are intrinsically probabilistic and result in correction operators that occur as byproducts of teleportation. These byproduct operators do not need to be corrected in the quantum hardware itself. Instead, byproduct operators are tracked through the circuit and output results reinterpreted. This tracking is routinely ignored in quantum information as it is assumed that tracking algorithms will eventually be developed. In this work we help fill this gap and present an algorithm for tracking byproduct operators through a quantum computation. We formulate this work based on quantum gate sets that are compatible with all major forms of quantum error correction and demonstrate the completeness of the algorithm.

Alexandru Paler; Simon J. Devitt; Kae Nemoto; Ilia Polian

2014-01-23

97

Probabilistic Simulation of Quantum Computation

Special stochastic representation of the wave function in Quantum Mechanics (QM), based on soliton realization of extended particles, is suggested with the aim to model quantum states via classical computer. Entangled solitons construction being introduced in the nonlinear spinor field model, the Einstein, Podolsky, Rosen (EPR) spin correlation is calculated and shown to coincide with the quantum mechanical one for the spin-1/2 particles in the singlet state. The concept of stochastic qubits is used for quantum computing modelling.

T. F. Kamalov; Yu. P. Rybakov

2007-03-16

98

Genetic Algorithms and Quantum Computation

Recently, researchers have applied genetic algorithms (GAs) to address some\\u000aproblems in quantum computation. Also, there has been some works in the\\u000adesigning of genetic algorithms based on quantum theoretical concepts and\\u000atechniques. The so called Quantum Evolutionary Programming has two major\\u000asub-areas: Quantum Inspired Genetic Algorithms (QIGAs) and Quantum Genetic\\u000aAlgorithms (QGAs). The former adopts qubit chromosomes as representations

Gilson A. Giraldi; Renato Portugal; Ricardo N. Thess

2004-01-01

99

Cluster-state quantum computation

This article is a short introduction to and review of the cluster-state model of quantum computation, in which coherent quantum information processing is accomplished via a sequence of single-qubit measurements applied to a fixed quantum state known as a cluster state. We also discuss a few novel properties of the model, including a proof that the cluster state cannot occur as the exact ground state of any naturally occurring physical system, and a proof that measurements on any quantum state which is linearly prepared in one dimension can be efficiently simulated on a classical computer, and thus are not candidates for use as a substrate for quantum computation.

Michael A. Nielsen

2005-07-01

100

Quantum computing for pattern classification

It is well known that for certain tasks, quantum computing outperforms classical computing. A growing number of contributions try to use this advantage in order to improve or extend classical machine learning algorithms by methods of quantum information theory. This paper gives a brief introduction into quantum machine learning using the example of pattern classification. We introduce a quantum pattern classification algorithm that draws on Trugenberger's proposal for measuring the Hamming distance on a quantum computer (CA Trugenberger, Phys Rev Let 87, 2001) and discuss its advantages using handwritten digit recognition as from the MNIST database.

Maria Schuld; Ilya Sinayskiy; Francesco Petruccione

2014-12-11

101

Multi-party Quantum Computation

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.

Adam Smith

2001-11-06

102

Quantum technology and its applications

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.

Boshier, Malcolm [Los Alamos National Laboratory; Berkeland, Dana [USG; Govindan, Tr [ARO; Abo - Shaeer, Jamil [DARPA

2010-12-10

103

Fourier Transforms and Quantum Computation

The foundations of computer science are built upon the modified Church-Turing thesis. This thesis states that any reasonable\\u000a model of computation can be simulated by a probabilistic Turing Machine with at most polynomial factor simulation overhead\\u000a (see [10] for a discussion). Early interest in quantum computation from a computer science perspective was sparked by results indicating\\u000a that quantum computers violate

Umesh V. Vazirani

2000-01-01

104

Prospects on Planar Quantum Computing

High-fidelity planar quantum circuits have been recently experimentally demonstrated, enabling a new generation of quantum computing, based on reliable, monolithically integrated planar optical devices. The present paper is a contribution to the development of this new concept, giving a general and at most comprehensive overview of quantum algorithms that can be implemented using planar optics devices. Starting from the four

Gabriella Cincotti

2009-01-01

105

Programming a Topological Quantum Computer

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.

Simon J. Devitt; Kae Nemoto

2012-09-07

106

Simulating chemistry using quantum computers

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.

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

2010-07-15

107

Quantum Computation with Trapped Ions

Trapped ions can be prepared, manipulated and analyzed with high fidelities. In addition, scalable ion trap architectures have been proposed (Kielpinski et al., Nature 417, 709 (2001).). Therefore trapped ions represent a promising approach to large scale quantum computing. Here we concentrate on the recent advancements of generating entangled states with small ion trap quantum computers. In particular, the creation

H. Häffner; W. Hänsel; C. F. Roos; P. O. Schmidt; M. Riebe; M. Chwalla; D. Chek-Al-Kar; J. Benhelm; U. D. Rapol; T. Körber; C. Becher; O. Gühne; W. Dür; R. Blatt

2008-01-01

108

Inventors Document: P1337 Category: Computing Technologies, Hardware License Status: Available to License Texas Industry Cluster: Information and Computer Technology Quantum dot applications for flash design using a protein-templated array of quantum dots reduces failure rates. When combined with a new

Lightsey, Glenn

109

7 Quantum Computing Applications of Genetic Programming

Quantum computers are computational devices that use the dynamics of atomic-scale objects to store and manipulate information. Only a few, small-scale quantum computers have been built to date, but quantum computers can in principle outperform all possible classical computers in significant ways. Quantum computation is therefore a subject of considerable theoretical interest that may also have practical applications in the

Lee Spector; Howard Barnum; Herbert J. Bernstein; Nikhil Swamy

110

Quantum Nash Equilibria and Quantum Computing

NASA Astrophysics Data System (ADS)

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

Fellman, Philip Vos; Post, Jonathan Vos

111

The Physics of Quantum Computation

NASA Astrophysics Data System (ADS)

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.

Falci, Giuseppe; Paladino, Elisabette

2015-10-01

112

Quantum computing with defects

NASA Astrophysics Data System (ADS)

The development of a quantum computer is contingent upon the identification and design of systems for use as qubits, the basic units of quantum information. One of the most promising candidates consists of a defect in diamond known as the nitrogen-vacancy (NV-1) center, since it is an individually-addressable quantum system that can be initialized, manipulated, and measured with high fidelity at room temperature. While the success of the NV-1 stems from its nature as a localized "deep-center" point defect, no systematic effort has been made to identify other defects that might behave in a similar way. We provide guidelines for identifying other defect centers with similar properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate systems. To elucidate these points, we compare electronic structure calculations of the NV-1 center in diamond with those of several deep centers in 4H silicon carbide (SiC). Using hybrid functionals, we report formation energies, configuration-coordinate diagrams, and defect-level diagrams to compare and contrast the properties of these defects. We find that the NCVSi-1 center in SiC, a structural analog of the NV-1 center in diamond, may be a suitable center with very different optical transition energies. We also discuss how the proposed criteria can be translated into guidelines to discover NV analogs in other tetrahedrally coordinated materials.[4pt] [1] J. R. Weber, W. F. Koehl, J. B. Varley, A. Janotti, B. B. Buckley, C. G. Van de Walle, and D. D. Awschalom, Proc. Nat. Acad. Sci. 107, 8513 (2010).

Varley, Joel

2011-03-01

113

Efficient Universal Blind Quantum Computation

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

114

Simulating quantum computing: Quantum eXpress

Quantum computing (QC) research has gained a lot of momentum recently due to several theoretical analyses that indicate that QC is significantly more efficient at solving certain classes of problems than classical computing. While experimental validation will ultimately be required, the primitive nature of current QC hardware leaves practical testing limited to trivial examples. Thus, a robust simulator is needed

Kareem S. Aggour; Renee Guhde; M. K. Sommins; Michael J. Simon

2003-01-01

115

Database Manipulation on Quantum Computers

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

Ahmed Younes

2007-05-29

116

Toward a superconducting quantum computer

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

Tsai, Jaw-Shen

2010-01-01

117

Quantum computation with quantum dot excitons

Potential application of elementary excitation in semiconductor quantum dot to quantum computation is discussed. We propose a scalable hardware and all optical implementation of a logic gate that exploits the discrete nature of electron-hole states and their well-concentrated oscillator strength for ultrafast gate operation. A multiple-bit gate function is based on the nearest neighbour dipole-dipole coupling. Rabi population oscillation and

H. Kamada; H. Gotoh

2004-01-01

118

Diagonal quantum circuits: their computational power and applications

Diagonal quantum circuits are quantum circuits comprising only diagonal gates in the computational basis. In spite of a classical feature of diagonal quantum circuits in the sense of commutativity of all gates, their computational power is highly likely to outperform classical one and they are exploited for applications in quantum informational tasks. We review computational power of diagonal quantum circuits and their applications. We focus on the computational power of instantaneous quantum polynomial-time (IQP) circuits, which are a special type of diagonal quantum circuits. We then review an approximate generation of random states as an application of diagonal quantum circuits, where random states are an ensemble of pure states uniformly distributed in a Hilbert space. We also present a thermalizing algorithm of classical Hamiltonians by using diagonal quantum circuits. These applications are feasible to be experimentally implemented by current technology due to a simple and robust structure of diagonal gates.

Yoshifumi Nakata; Mio Murao

2014-08-04

119

The new field of quantum error correction has developed spectacularly since its origin less than two years ago. Encoded quantum information can be protected from errors that arise due to uncontrolled interactions with the environment. Recovery from errors can work effectively even if occasional mistakes occur during the recovery procedure. Furthermore, encoded quantum information can be processed without serious propagation

John Preskill

1998-01-01

120

Distributed quantum computing: a distributed Shor algorithm

We present a distributed implementation of Shor's quantum factoring algorithm on a distributed quantum network model. This model provides a means for small capacity quantum computers to work together in such a way as to simulate a large capacity quantum computer. In this paper, entanglement is used as a resource for implementing non-local operations between two or more quantum computers.

Anocha Yimsiriwattana; Samuel J. Lomonaco Jr.

2004-01-01

121

Quantum Information and Computing

NASA Astrophysics Data System (ADS)

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 Lévy white noise functionals / K. Saitô -- 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.

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

2006-03-01

122

Quantum Computers, Factoring, and Decoherence

In a quantum computer any superposition of inputs evolves unitarily into the corresponding superposition of outputs. It has been recently demonstrated that such computers can dramatically speed up the task of finding factors of large numbers -- a problem of great practical significance because of its cryptographic applications. Instead of the nearly exponential ($\\sim \\exp L^{1/3}$, for a number with $L$ digits) time required by the fastest classical algorithm, the quantum algorithm gives factors in a time polynomial in $L$ ($\\sim L^2$). This enormous speed-up is possible in principle because quantum computation can simultaneously follow all of the paths corresponding to the distinct classical inputs, obtaining the solution as a result of coherent quantum interference between the alternatives. Hence, a quantum computer is sophisticated interference device, and it is essential for its quantum state to remain coherent in the course of the operation. In this report we investigate the effect of decoherence on the quantum factorization algorithm and establish an upper bound on a ``quantum factorizable'' $L$ based on the decoherence suffered per operational step.

I. Chuang; Raymond Laflamme; P. Shor; W. Zurek

1995-03-08

123

Quantum computation: Silicon comes back

NASA Astrophysics Data System (ADS)

The extraordinary long coherence times and high-fidelity manipulation of electron spins trapped in isotopically purified silicon could be an essential step towards the realization of a solid-state quantum computer.

Schreiber, Lars R.; Bluhm, Hendrik

2014-12-01

124

Quantum chromodynamics with advanced computing

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.

Kronfeld, Andreas S.; /Fermilab

2008-07-01

125

Children and Computers: New Technology--

31 Children and Computers: New Technology-- Old Concerns Ellen A.Wartella Nancy Jennings Abstract Computer technology has ushered in a new era of mass media, bringing with it great promise and great as being new, similar promises and con- cerns have accompanied each new wave of media technology throughout

Cassell, Justine

126

Computation and Dynamics: Classical and Quantum

NASA Astrophysics Data System (ADS)

We discuss classical and quantum computations in terms of corresponding Hamiltonian dynamics. This allows us to introduce quantum computations which involve parallel processing of both: the data and programme instructions. Using mixed quantum-classical dynamics we look for a full cost of computations on quantum computers with classical terminals.

Kisil, Vladimir V.

2010-05-01

127

Internet Archive: Computers & Technology

NSDL National Science Digital Library

The Internet Archive has gathered up this excellent audio collection featuring interviews, discussions, and musings about computers, technology, and science. All told, there are over 700 audio files here, including the popular Groks Science Radio Show and Podcast and Textfiles BBS Audio. This last collection contains a varied set of audio files assembled by Jason Scott, curator of textfiles.com. Here, visitors can learn about the days of ASCII and Dial-up Bulletin Board Systems (BBS) that were popular from the 1970s to the early 1990s. To get started, first-time visitors can look over the Most Downloaded Items for a few suggestions, or simply find out more via the About the Archive area.

128

Mesoporous matrices for quantum computation with improved response through redundance

We present a solid state implementation of quantum computation, which improves previously proposed optically driven schemes. Our proposal is based on vertical arrays of quantum dots embedded in a mesoporous material which can be fabricated with present technology. The redundant encoding typical of the chosen hardware protects the computation against gate errors and the effects of measurement induced noise. The

T. E. Hodgson; M. F. Bertino; N. Leventis; I. D'Amico

2007-01-01

129

Solid-State Quantum Computer Based on Scanning Tunneling Microscopy

We propose a solid-state nuclear spin quantum computer based on application of scanning tunneling microscopy (STM) and well-developed silicon technology. It requires the measurement of tunneling current modulation caused by the Larmor precession of a single electron spin. Our envisioned STM quantum computer would operate at the high magnetic field ($\\sim 10$T) and at low temperature $\\sim 1$K.

G. P. Berman; G. W. Brown; M. E. Hawley; V. I. Tsifrinovich

2001-03-03

130

Technical Report No. 2005-496 QUANTUM COMPUTATION AND QUANTUM

Technical Report No. 2005-496 QUANTUM COMPUTATION AND QUANTUM INFORMATION Marius Nagy and Selim G the eld of quantum computation and quantum information. The reader is rst familiarized with those features and principles of quantum mechanics providing a more e cient and secure information processing

Graham, Nick

131

Technical Report No. 2005496 QUANTUM COMPUTATION AND QUANTUM

Technical Report No. 2005Â496 QUANTUM COMPUTATION AND QUANTUM INFORMATION \\Lambda Marius Nagy the field of quantum computation and quantum information. The reader is first familiarized with those features and principles of quantum mechanics providing a more efficient and secure information processing

Graham, Nick

132

Adiabatic Cluster State Quantum Computing

Models of quantum computation are important because they change the physical requirements for achieving universal quantum computation (QC). For example, one-way QC requires the preparation of an entangled "cluster" state followed by adaptive measurement on this state, a set of requirements which is different from the standard quantum circuit model. Here we introduce a model based on one-way QC but without measurements (except for the final readout), instead using adiabatic deformation of a Hamiltonian whose initial ground state is the cluster state. This opens the possibility to use the copious results from one-way QC to build more feasible adiabatic schemes.

Bacon, Dave

2009-01-01

133

[Earth Science Technology Office's Computational Technologies Project

NASA Technical Reports Server (NTRS)

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.

Fischer, James (Technical Monitor); Merkey, Phillip

2005-01-01

134

Quantum ballistic evolution in quantum mechanics: Application to quantum computers

Quantum computers are important examples of processes whose evolution can be described in terms of iterations of single-step operators or their adjoints. Based on this, Hamiltonian evolution of processes with associated step operators T is investigated here. The main limitation of this paper is to processes which evolve quantum ballistically, i.e., motion restricted to a collection of nonintersecting or distinct

Paul Benioff

1996-01-01

135

A Grid Enabled Quantum Computer Simulator

Simulation of quantum computers using classical computers is a computationally hard problem, requiring a huge amount of operations and storage. Grid systems are a good choice for simulating quantum algorithms, since they provide access to high-performance computer clusters. In this paper we present the design of a message passing parallel version of the quantum computer simulator, QCL, deployed as a

Simona Caraiman; Alexandru Archip; Vasile Manta

2009-01-01

136

Polynomial time quantum computation with advice

Advice is supplementary information that enhances the computational power of an underlying computation. This paper focuses on advice that is given in the form of a pure quantum state and examines the influence of such advice on the behaviors of an underlying polynomial-time quantum computation with bounded-error probability. 1 Prologue Quantum computation has emerged to shape a future computational paradigm

Harumichi Nishimura; Tomoyuki Yamakami

2003-01-01

137

Quantum computing in power system simulation

The concept of quantum computing has been conjectured as the next major breakthrough in computing. The basis of quantum computing, its strengths, weaknesses, and challenges are outlined. The specific application to electric power engineering is discussed.

Daniel J. Tylavsky; G. T. Heydt

2003-01-01

138

Teleportation in a nuclear spin quantum computer

We present a procedure for quantum teleportation in a nuclear spin quantum computer in which quantum logic gates are implemented by using selective electromagnetic pulses. A sequence of pulses is combined with single-spin measurements in the sigmaz basis for fast transfer of information in a spin quantum computer. We simulated this procedure for quantum teleportation in a nuclear spin chain

Gennady P. Berman; Gustavo V. López; Vladimir I. Tsifrinovich

2002-01-01

139

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

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.

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

2000-03-18

140

Prospective Algorithms for Quantum Evolutionary Computation

This effort examines the intersection of the emerging field of quantum computing and the more established field of evolutionary computation. The goal is to understand what benefits quantum computing might offer to computational intelligence and how computational intelligence paradigms might be implemented as quantum programs to be run on a future quantum computer. We critically examine proposed algorithms and methods for implementing computational intelligence paradigms, primarily focused on heuristic optimization methods including and related to evolutionary computation, with particular regard for their potential for eventual implementation on quantum computing hardware.

Sofge, Donald A

2008-01-01

141

Strengths and Weaknesses of Quantum Computing

Recently a great deal of attention has focused on quantum computation following a sequence of results suggesting that quantum computers are more powerful than classical probabilistic computers. Following Shor's result that factoring and the extraction of discrete logarithms are both solvable in quantum polynomial time, it is natural to ask whether all of NP can be efficiently solved in quantum

Charles H. Bennett; Ethan Bernstein; Gilles Brassard; Umesh V. Vazirani

1997-01-01

142

On the Problem of Programming Quantum Computers

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.

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

2000-01-01

143

On quantum computing with macroscopic Josephson qubits

The achievements of quantum computation theory, e.g. Shor's factoring algorithm, motivate efforts to realize quantum computers. Among systems proposed for quantum computing, macroscopic superconducting circuits of Josephson junctions appear promising for integration in electronic circuits and large-scale applications. Recently, a superconducting tunnel junction circuit was designed and a sufficiently high quality factor of quantum coherence has been obtained. This indicates

Jie Han; Pieter Jonker

2002-01-01

144

Computer Viruses. Technology Update.

ERIC Educational Resources Information Center

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…

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

145

Universal Single-Server Blind Quantum Computation for Classical Client

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.

Hai-Ru Xu; Bang-Hai Wang

2014-11-12

146

Computational model underlying the one-way quantum computer

In this paper we present the computational model underlying the one-way quantum computer which we introduced recently [Phys. Rev. Lett. 86, 5188 (2001)]. The one-way quantum computer has the property that any quantum logic network can be simulated on it. Conversely, not all ways of quantum information processing that are possible with the one-way quantum computer can be understood properly

Robert Raussendorf; Hans Briegel

2001-01-01

147

Computable functions, quantum measurements, and quantum dynamics

We construct quantum mechanical observables and unitary operators which, if implemented in physical systems as measurements and dynamical evolutions, would contradict the Church-Turing thesis which lies at the foundation of computer science. We conclude that either the Church-Turing thesis needs revision, or that only restricted classes of observables may be realized, in principle, as measurements, and that only restricted classes of unitary operators may be realized, in principle, as dynamics.

M. A. Nielsen

1997-06-03

148

Quantum Computing in Plato's Cave

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.

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

2014-03-23

149

Control aspects of quantum computing using pure and mixed states

Steering quantum dynamics such that the target states solve classically hard problems is paramount to quantum simulation and computation. And beyond, quantum control is also essential to pave the way to quantum technologies. Here, important control techniques are reviewed and presented in a unified frame covering quantum computational gate synthesis and spectroscopic state transfer alike. We emphasize that it does not matter whether the quantum states of interest are pure or not. While pure states underly the design of quantum circuits, ensemble mixtures of quantum states can be exploited in a more recent class of algorithms: it is illustrated by characterizing the Jones polynomial in order to distinguish between different (classes of) knots. Further applications include Josephson elements, cavity grids, ion traps and nitrogen vacancy centres in scenarios of closed as well as open quantum systems. PMID:22946034

Schulte-Herbrüggen, Thomas; Marx, Raimund; Fahmy, Amr; Kauffman, Louis; Lomonaco, Samuel; Khaneja, Navin; Glaser, Steffen J.

2012-01-01

150

A Blueprint for a Topologically Fault-tolerant Quantum Computer

The advancement of information processing into the realm of quantum mechanics promises a transcendence in computational power that will enable problems to be solved which are completely beyond the known abilities of any "classical" computer, including any potential non-quantum technologies the future may bring. However, the fragility of quantum states poses a challenging obstacle for realization of a fault-tolerant quantum computer. The topological approach to quantum computation proposes to surmount this obstacle by using special physical systems -- non-Abelian topologically ordered phases of matter -- that would provide intrinsic fault-tolerance at the hardware level. The so-called "Ising-type" non-Abelian topological order is likely to be physically realized in a number of systems, but it can only provide a universal gate set (a requisite for quantum computation) if one has the ability to perform certain dynamical topology-changing operations on the system. Until now, practical methods of implementing thes...

Bonderson, Parsa; Freedman, Michael; Nayak, Chetan

2010-01-01

151

Spin-based quantum computation in multielectron quantum dots

In a quantum computer the hardware and software are intrinsically connected because the quantum Hamiltonian (or more precisely its time development) is the code that runs the computer. We demonstrate this subtle and crucial relationship by considering the example of electron-spin-based solid-state quantum computer in semiconductor quantum dots. We show that multielectron quantum dots with one valence electron in the

Xuedong Hu; S. Das Sarma

2001-01-01

152

The One Way to Quantum Computation

Measurement-based quantum computation has emerged from the physics community as a new approach to quantum computation where\\u000a measurements rather than unitary transformations are the main driving force of computation. Among measurement-based quantum\\u000a computation methods the recently introduced one-way quantum computer [RB01] stands out as basic and fundamental.\\u000a \\u000a In this work we a concrete syntax and an algebra of these patterns

Vincent Danos; Elham Kashefi; Prakash Panangaden

2006-01-01

153

Quantum to classical phase transition in noisy quantum computers

The fundamental problem of the transition from quantum to classical physics is usually explained by decoherence, and viewed as a gradual process. The study of entanglement, or quantum correlations, in noisy quantum computers implies that in some cases the transition from quantum to classical is actually a phase transition. We define the notion of entanglement length in d-dimensional noisy quantum

Dorit Aharonov

2000-01-01

154

Ion Trap Quantum Computing with Ca + Ions

The scheme of an ion trap quantum computer is described and the implementation of quantum gate operations with trapped Ca+ ions is discussed. Quantum information processing with Ca+ ions is exemplified with several recent experiments investigating entanglement of ions.

R. Blatt; H. Häffner; C. F. Roos; C. Becher; F. Schmidt-Kaler

2004-01-01

155

Ion Trap Quantum Computing with Ca + Ions

The scheme of an ion trap quantum computer is described and the implementation of quantum gate operations with trapped Ca+ ions is discussed. Quantum information processing with Ca+ ions is exemplified with several recent experiments investigating entanglement of ions.

R. Blatt; H. Häffner; C. F. Roos; C. Becher; F. Schmidt-Kaler

156

Impossibility of secure cloud quantum computing for classical client

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.

Tomoyuki Morimae; Takeshi Koshiba

2014-07-07

157

Quantum computers: Achievements, implementation difficulties, and prospects

A review of the principles of operation of quantum computers and their elements is presented. The radical advantage of quantum\\u000a algorithms for processing information over the classical ones is discussed, quantum entanglement is considered as the basic\\u000a resource of quantum computations, and the most promising and interesting proposals on realization of quantum computers on\\u000a the basis of trapped ions, nuclear

Yu. I. Bogdanov; K. A. Valiev; A. A. Kokin

2011-01-01

158

Universal Blind Quantum Computation

We present a protocol which allows a client to have a server carry out a\\u000aquantum computation for her such that the client's inputs, outputs and\\u000acomputation remain perfectly private, and where she does not require any\\u000aquantum computational power or memory. The client only needs to be able to\\u000aprepare single qubits randomly chosen from a finite set and

Anne Broadbent; Joseph Fitzsimons; Elham Kashefi

2009-01-01

159

Efficient fault-tolerant quantum computing

Fault tolerant quantum computing methods which work with efficient quantum error correcting codes are discussed. Several new techniques are introduced to restrict accumulation of errors before or during the recovery. Classes of eligible quantum codes are obtained, and good candidates exhib- ited. This permits a new analysis of the permissible error rates and minimum overheads for robust quantum computing. It

Andrew M. Steane

160

Models of Quantum Computers and Decoherence Problem

Mathematical models of quantum computers such as a multidimensional quantum Turing machine and quantum circuits are described and its relations with lattice spin models are discussed. One of the main open problems one has to solve if one wants to build a quantum computer is the decoherence due to the coupling with the environment. We propose a possible solution of

I. V. Volovich

1999-01-01

161

Computational model underlying the one-way quantum computer

In this paper we present the computational model underlying the one-way quantum computer which we introduced recently [Phys. Rev. Lett 86, 5188 (2001)]. The one-way quantum computer has the property that any quantum logic network can be simulated on it. Conversely, not all ways of quantum information processing that are possible with the one-way quantum computer can be explained within a network model. As a consequence, the temporal complexity is, for certain algorithms, lower than in networks. For example, every circuit in the Clifford group can be performed on the one-way quantum computer in a single time step.

Raussendorf, R; Raussendorf, Robert; Briegel, Hans

2001-01-01

162

Quantum computing and hidden variables

This paper initiates the study of hidden variables from a quantum computing perspective. For us, a hidden-variable theory is simply a way to convert a unitary matrix that maps one quantum state to another into a stochastic matrix that maps the initial probability distribution to the final one in some fixed basis. We list five axioms that we might want such a theory to satisfy and then investigate which of the axioms can be satisfied simultaneously. Toward this end, we propose a new hidden-variable theory based on network flows. In a second part of the paper, we show that if we could examine the entire history of a hidden variable, then we could efficiently solve problems that are believed to be intractable even for quantum computers. In particular, under any hidden-variable theory satisfying a reasonable axiom, we could solve the graph isomorphism problem in polynomial time, and could search an N-item database using O(N{sup 1/3}) queries, as opposed to O(N{sup 1/2}) queries with Grover's search algorithm. On the other hand, the N{sup 1/3} bound is optimal, meaning that we could probably not solve NP-complete problems in polynomial time. We thus obtain the first good example of a model of computation that appears slightly more powerful than the quantum computing model.

Aaronson, Scott [Institute for Advanced Study, Princeton, New Jersey 08540 (United States)

2005-03-01

163

Emerging Models and Technologies for Computation (EMT) Program Solicitation

such as biological systems, quantum phenomena, nanoscale science and engineering, and other novel computing concepts. To bring fundamental changes to software, hardware and architectural design aspects of future computingEmerging Models and Technologies for Computation (EMT) Program Solicitation NSF 07-523 Replaces

Mazumder, Pinaki

164

Computer Technology for Industry.

ERIC Educational Resources Information Center

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…

Aviation/Space, 1982

1982-01-01

165

ROM-based computation: quantum versus classical

We introduce a model of computation based on read only memory (ROM), which allows us to compare the space-efficiency of reversible, error-free classical computation with reversible, error-free quantum computation. We show that a ROM-based quantum computer with one writable qubit is universal, whilst two writable bits are required for a universal classical ROM-based computer. We also comment on the time-efficiency advantages of quantum computation within this model.

B. C. Travaglione; M. A. Nielsen; H. M. Wiseman; A. Ambainis

2001-09-04

166

Programming physical realizations of quantum computers

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

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

2001-01-01

167

Introduction to Grassmann Manifolds and Quantum Computation

Geometrical aspects of quantum computing are reviewed elementarily for non-experts and\\/or graduate students who are interested in both Geometry and Quantum Computation. In the first half we show how to treat Grassmann manifolds which are very important examples of manifolds in Mathematics and Physics. Some of their applications to Quantum Computation and its efficiency problems are shown in the second

Kazuyuki Fujii

2001-01-01

168

Quantum Darwinism and Computability Theory

This paper examines whether unitary evolution alone is sufficient to explain emergence of the classical world from the perspective of computability theory. Specifically, it looks at the problem of how the choice related to the measurement is made by the observer viewed as a quantum system. In interpretations where the system together with the observers is completely described by unitary transformations, the observer cannot make any choices and so measurement is impossible. From the perspective of computability theory, a quantum machine cannot halt and so it cannot observe the computed state, indicating that unitarity alone does not explain all matter processes. Further it is argued that the consideration of information and observation requires an overarching system of knowledge and expectations about outcomes.

Subhash Kak

2014-10-23

169

Computable measure of quantum correlation

NASA Astrophysics Data System (ADS)

A general state of an system is a classical-quantum state if and only if its associated -correlation matrix (a matrix constructed from the coherence vector of the party , the correlation matrix of the state, and a function of the local coherence vector of the subsystem ), has rank no larger than . Using the general Schatten -norms, we quantify quantum correlation by measuring any violation of this condition. The required minimization can be carried out for the general -norms and any function of the local coherence vector of the unmeasured subsystem, leading to a class of computable quantities which can be used to capture the quantumness of correlations due to the subsystem . We introduce two special members of these quantifiers: The first one coincides with the tight lower bound on the geometric measure of discord, so that such lower bound fully captures the quantum correlation of a bipartite system. Accordingly, a vanishing tight lower bound on the geometric discord is a necessary and sufficient condition for a state to be zero-discord. The second quantifier has the property that it is invariant under a local and reversible operation performed on the unmeasured subsystem, so that it can be regarded as a computable well-defined measure of the quantum correlations. The approach presented in this paper provides a way to circumvent the problem with the geometric discord. We provide some examples to exemplify this measure.

Akhtarshenas, S. Javad; Mohammadi, Hamidreza; Karimi, Saman; Azmi, Zahra

2015-01-01

170

Gate count estimates for performing quantum chemistry on small quantum computers

As quantum computing technology improves and quantum computers with a small but non-trivial number of N > 100 qubits appear feasible in the near future the question of possible applications of small quantum computers gains importance. One frequently mentioned application is Feynman's original proposal of simulating quantum systems, and in particular the electronic structure of molecules and materials. In this paper, we analyze the computational requirements for one of the standard algorithms to perform quantum chemistry on a quantum computer. We focus on the quantum resources required to find the ground state of a molecule twice as large as what current classical computers can solve exactly. We find that while such a problem requires about a ten-fold increase in the number of qubits over current technology, the required increase in the number of gates that can be coherently executed is many orders of magnitude larger. This suggests that for quantum computation to become useful for quantum chemistry problems, drastic algorithmic improvements will be needed.

Dave Wecker; Bela Bauer; Bryan K. Clark; Matthew B. Hastings; Matthias Troyer

2014-07-11

171

Simulating quantum dynamics on a quantum computer

NASA Astrophysics Data System (ADS)

We explicitly show how to simulate time-dependent sparse Hamiltonian evolution on a quantum computer, with complexity that is close to linear in the evolution time. The complexity also depends on the magnitude of the derivatives of the Hamiltonian. We propose a range of techniques to simulate Hamiltonians with badly behaved derivatives. These include using adaptive time steps, adapting the order of the integrators, and omitting regions about discontinuities. The complexity of the algorithm is quantified by calls to an oracle, which yields information about the Hamiltonian, and accounts for all computational resources. We explicitly determine the number of bits of output that this oracle needs to provide, and show how to efficiently perform the required 1-sparse unitary operations using these bits. We also account for discretization error in the time, as well as accounting for Hamiltonians that are a sum of terms that are sparse in different bases.

Wiebe, Nathan; Berry, Dominic W.; Høyer, Peter; Sanders, Barry C.

2011-11-01

172

RISQ - reduced instruction set quantum computers

NASA Astrophysics Data System (ADS)

Candidates for quantum computing which offer only restricted control, e.g., due to lack of access to individual qubits, are not useful for general purpose quantum computing. We present concrete proposals for the use of systems with such limitations as RISQ - reduced instruction set quantum computers and devices - for simulation of quantum dynamics, for multi-particle entanglement and squeezing of collective spin variables. These tasks are useful in their own right, and they also provide experimental probes for the functioning of quantum gates in pre-mature proto-types of quantum computers.

Mølmer, Klaus; Sørensen, Anders

2000-11-01

173

Computer Technology and Social Issues.

ERIC Educational Resources Information Center

Computing involves social issues and political choices. Issues such as privacy, computer crime, gender inequity, disemployment, and electronic democracy versus "Big Brother" are addressed in the context of efforts to develop a national public policy for information technology. A broad range of research and case studies are examined in an attempt…

Garson, G. David

174

Classical Simulation and Complexity of Quantum Computations

\\u000a Quantum computing is widely regarded as being able to offer computational complexity benefits beyond the possibilities of\\u000a classical computing. Yet the relationship of quantum to classical computational complexity is little understood. A fundamental\\u000a approach to exploring this issue is to study the extent to which quantum computations (especially with restricted sub-universal\\u000a ingredients) can be classically efficiently simulated. We will discuss

Richard Jozsa

2010-01-01

175

Computer Technology for Industry

NASA Technical Reports Server (NTRS)

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.

1982-01-01

176

Quantum computing and the entanglement frontier

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 sy...

Preskill, John

2012-01-01

177

Information Technology: Computer Systems Engineer

NSDL National Science Digital Library

In this video adapted from Pathways to Technology, learn what drove Choice JenningsÃ¢ÂÂsomeone who had never owned a computer of his ownÃ¢ÂÂto become interested in computer graphics, attend community college, earn an associate's degree in computer systems engineering (CSE), and start his own information technology (IT) business. Also see the many roles a CSE professional can play, from systems administrator to IT director.The video runs 2:45 and is accompanied by a background essay, standards alignment, and discussion questions. Users who sign up for a free account can save the resource and download the video as well.

2012-05-30

178

Trusted Computing Technologies, Intel Trusted Execution Technology.

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.

Guise, Max Joseph; Wendt, Jeremy Daniel

2011-01-01

179

Geometry of Quantum Computation with Qutrits

Determining the quantum circuit complexity of a unitary operation is an important problem in quantum computation. By using the mathematical techniques of Riemannian geometry, we investigate the efficient quantum circuits in quantum computation with n qutrits. We show that the optimal quantum circuits are essentially equivalent to the shortest path between two points in a certain curved geometry of SU(3n). As an example, three-qutrit systems are investigated in detail. PMID:24005379

Li, Bin; Yu, Zu-Huan; Fei, Shao-Ming

2013-01-01

180

Quantum simulators A new tool to tackle computational quantum

Quantum simulators A new tool to tackle computational quantum many-body problems Jonas Larson #12;Motivation "Take-home-message" Scenario 1: A quantum wire described by a Heisenberg chain-Carlo. 5 #12;Motivation "Take-home-message" 6 Think twice which quantum problem you tell your student

181

Suppression of quantum chaos in a quantum computer hardware

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

J. Lages; D. L. Shepelyansky

2006-01-01

182

A simulator for quantum computer hardware

The Quantum Computer Emulator (QCE) described in this paper consists of a simulator of a generic, general purpose quantum computer and a graphical user interface. The latter is used to control the sim- ulator, to dene the hardware of the quantum computer and to debug and execute quantum algorithms. QCE runs in a Windows 98\\/NT\\/2000\\/ME\\/XP environment. It can be used

Koen De Raedt; Hans De Raedt; Kristel Michielsen

2002-01-01

183

QCE: A Simulator for Quantum Computer Hardware

The Quantum Computer Emulator (QCE) described in this paper consists of a simulator of a generic, general purpose quantum computer and a graphical user interface. The latter is used to control the simulator, to define the hardware of the quantum computer and to debug and execute quantum algorithms. QCE runs in a Windows 98\\/NT\\/2000\\/ME\\/XP environment. It can be used to

Kristel Michielsen; Hans de Raedt

2003-01-01

184

Classical Control of Large-Scale Quantum Computers

The accelerated development of quantum technology has reached a pivotal point. Early in 2014, several results were published demonstrating that several experimental technologies are now accurate enough to satisfy the requirements of fault-tolerant, error corrected quantum computation. While there are many technological and experimental issues that still need to be solved, the ability of experimental systems to now have error rates low enough to satisfy the fault-tolerant threshold for several error correction models is a tremendous milestone. Consequently, it is now a good time for the computer science and classical engineering community to examine the {\\em classical} problems associated with compiling quantum algorithms and implementing them on future quantum hardware. In this paper, we will review the basic operational rules of a topological quantum computing architecture and outline one of the most important classical problems that need to be solved; the decoding of error correction data for a large-scale quantum computer. We will endeavour to present these problems independently from the underlying physics as much of this work can be effectively solved by non-experts in quantum information or quantum mechanics.

Simon J. Devitt

2014-05-20

185

Relativistic Quantum Metrology: Exploiting relativity to improve quantum measurement technologies

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.

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

2014-04-29

186

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

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

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

2014-01-01

187

Review: Towards Spintronic Quantum Technologies with Dopants in Silicon

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.

Gavin W. Morley

2014-07-23

188

Measurement-only topological quantum computation.

We remove the need to physically transport computational anyons around each other from the implementation of computational gates in topological quantum computing. By using an anyonic analog of quantum state teleportation, we show how the braiding transformations used to generate computational gates may be produced through a series of topological charge measurements. PMID:18764095

Bonderson, Parsa; Freedman, Michael; Nayak, Chetan

2008-07-01

189

The Quantum Human Computer (QHC) Hypothesis

ERIC Educational Resources Information Center

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…

Salmani-Nodoushan, Mohammad Ali

2008-01-01

190

Brain Neurons as Quantum Computers:

NASA Astrophysics Data System (ADS)

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.

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

191

Strain effects on silicon donor exchange: Quantum computer architecture considerations

Proposed silicon-based quantum-computer architectures have attracted attention because of their promise for scalability and their potential for synergetically utilizing the available resources associated with the existing infrastructure of the powerful Si technology. Quantitative understanding of and precise physical control over donor (e.g., phosphorus) exchange are crucial elements in the physics underlying the proposed Si-based quantum-computer hardware. An important potential problem

Belita Koiller; Xuedong Hu

2002-01-01

192

Mesoporous matrices for quantum computation with improved response through redundance

We present a solid state implementation of quantum computation, which improves previously proposed optically driven schemes. Our proposal is based on vertical arrays of quantum dots embedded in a mesoporous material which can be fabricated with present technology. The redundant encoding typical of the chosen hardware protects the computation against gate errors and the effects of measurement induced noise. The system parameters required for quantum computation applications are calculated for II-VI and III-V materials and found to be within the experimental range. The proposed hardware may help minimize errors due to polydispersity of dot sizes, which is at present one of the main problems in relation to quantum dot-based quantum computation.

Hodgson, T; Leventis, N; D'Amico, I; 10.1063/1.2745438

2009-01-01

193

Exploiting locality in quantum computation for quantum chemistry

Accurate prediction of chemical and material properties from first principles quantum chemistry is a challenging task on traditional computers. Recent developments in quantum computation offer a route towards highly accurate solutions with polynomial cost, however this solution still carries a large overhead. In this perspective, we aim to bring together known results about the locality of physical interactions from quantum chemistry with ideas from quantum computation. We show that the utilization of spatial locality combined with the Bravyi-Kitaev transformation offers an improvement in the scaling of known quantum algorithms for quantum chemistry and provide numerical examples to help illustrate this point. We combine these developments to improve the outlook for the future of quantum chemistry on quantum computers.

Jarrod R. McClean; Ryan Babbush; Peter J. Love; Alán Aspuru-Guzik

2014-07-29

194

Suppression of quantum chaos in a quantum computer hardware

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.

J. Lages; D. L. Shepelyansky

2005-10-14

195

Efficient one-way quantum computations for quantum error correction

NASA Astrophysics Data System (ADS)

We show how to explicitly construct an O(nd) size and constant quantum depth circuit which encodes any given n-qubit stabilizer code with d generators. Our construction is derived using the graphic description for stabilizer codes and the one-way quantum computation model. Our result demonstrates how to use cluster states as scalable resources for many multi-qubit entangled states and how to use the one-way quantum computation model to improve the design of quantum algorithms.

Huang, Wei; Wei, Zhaohui

2009-07-01

196

Efficient One-way Quantum Computations for Quantum Error Correction

We show how to explicitly construct an $O(nd)$ size and constant quantum depth circuit which encodes any given $n$-qubit stabilizer code with $d$ generators. Our construction is derived using the graphic description for stabilizer codes and the one-way quantum computation model. Our result demonstrates how to use cluster states as scalable resources for many multi-qubit entangled states and how to use the one-way quantum computation model to improve design of quantum algorithms.

Huang, Wei

2007-01-01

197

Problems and Prospects for Quantum Computational Speedup

This paper studies the problems involved in the speed-up of the classical computational algorithms using the quantum computational\\u000a paradigm. In particular, we relate the primitive recursive function approach used in computability theory with the harmonic\\u000a oscillator basis used in quantum physics. Also, we raise some basic issues concerning quantum computational paradigm: these\\u000a include failures in programmability and scalability, limitation on

E. V. Krishnamurthy

2003-01-01

198

Stabilisation of Quantum Computations by Symmetrisation

We propose a method for the stabilisation of quantum computations (including quantum state storage). The method is based on the operation of projection into $\\\\cal SYM$, the symmetric subspace of the full state space of $R$ redundant copies of the computer. We describe an efficient algorithm and quantum network effecting $\\\\cal SYM$--projection and discuss the stabilising effect of the proposed

Adriano Barenco; David Deutsch; Artur Ekert; Richard Jozsa; Chiara Macchiavello

1996-01-01

199

Geometry, optimal control and quantum computing

Quantum computation promises solution to problems that are hard to solve by classical computers. The efficient construction of quantum circuits that can solve interesting tasks is a fundamental challenge in the field. Such efficient construction also reduces decoherence losses in physical implementations of quantum algorithms by reducing interaction time with the environment. Therefore, finding time-optimal ways to synthesize unitary transformations

Haidong Yuan

2006-01-01

200

We present a scheme of quantum computation that consists entirely of one-qubit measurements on a particular class of entangled states, the cluster states. The measurements are used to imprint a quantum logic circuit on the state, thereby destroying its entanglement at the same time. Cluster states are thus one-way quantum computers and the measurements form the program.

Robert Raussendorf; Hans J. Briegel

2001-01-01

201

NASA Astrophysics Data System (ADS)

We present a scheme of quantum computation that consists entirely of one-qubit measurements on a particular class of entangled states, the cluster states. The measurements are used to imprint a quantum logic circuit on the state, thereby destroying its entanglement at the same time. Cluster states are thus one-way quantum computers and the measurements form the program.

Raussendorf, Robert; Briegel, Hans J.

2001-05-01

202

Computational Methods for Simulating Quantum Computers H. De Raedt

-Formula Algorithms 17 F. Comments 19 IV. Quantum Algorithms 19 A. Elementary Gates 21 1. Hadamard Gate 21 2. Swap computer is a complicated many-body system that interacts with its environment. In quantum statistical mechanics and quantum chemistry, it is well known that simulating an interacting quantum many-body system

203

Quantum computing: beyond the limits of conventional computation

The quantum model of computation not only offers entirely new ways to manipulate information, but also allows information processing tasks to be formulated in unconventional, genuine quantum mechanical terms. We show that the task of distinguishing among entangled quantum states combines entanglement and non-determinism in a way that makes the quantum solution impossible to simulate on any classical machine (even

Marius Nagy; Selim G. Akl

2007-01-01

204

Quantum Computation Beyond the "Standard Circuit Model"

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.

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

2006-08-16

205

Quantum spin dynamics as a model for quantum computer operation

: We study effects of the physical realization of quantum computers on their logical operation. Through simulation of physical\\u000a models of quantum computer hardware, we analyze the difficulties that are encountered in programming physical realizations\\u000a of quantum computers. Examples of logically identical implementations of the controlled-NOT operation and Grover's database\\u000a search algorithm are used to demonstrate that the results of

H. De Raedt; K. Michielsen; A. Hams; S. Miyashita; K. Saito

2002-01-01

206

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

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

Fernandez, Thomas

207

Non-unitary probabilistic quantum computing

NASA Technical Reports Server (NTRS)

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.

Gingrich, Robert M.; Williams, Colin P.

2004-01-01

208

Quantum computing with superconductors I: Architectures

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.

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

2006-03-24

209

Physics and computer science: quantum computation and other approaches

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).

Salvador E. Venegas-Andraca

2011-03-07

210

The curriculum needs for quantum computing (QC), quantum information (QI), and quantum encryption (QE) are discussed. QC is an application of Quantum Mechanics (Messiah 1958) to the problem of defining a computer using quantum phenomena. QI is an expansion of quan- tum mechanics analogous to classical information theory, and QE is an application of QI. Now that the first venture

Ronald I. Frank

211

Quantum Monte Carlo Endstation for Petascale; Computing

NCSU research group has been focused on accomplising the key goals of this initiative: establishing new generation of quantum Monte Carlo (QMC) computational tools as a part of Endstation petaflop initiative for use at the DOE ORNL computational facilities and for use by computational electronic structure community at large; carrying out high accuracy quantum Monte Carlo demonstration projects in application

Lubos Mitas

2011-01-01

212

Exploring Tuning Strategies for Quantum Chemistry Computations

Exploring Tuning Strategies for Quantum Chemistry Computations Lakshminarasimhan Seshagiri1 , Meng: Multi-Core, GAMESS, Niagara, Adaptation, NICAN, TAU,Quantum Chemistry 1 Introduction Computational-Shiou Wu1 , Masha Sosonkina1 , and Zhao Zhang2 1 Scalable Computing Laboratory, The Ames Laboratory, US Do

Sosonkina, Masha

213

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

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

Lenhard, Johannes

2014-12-01

214

Optical Computers and Space Technology

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

215

Ultrafast Pulse Shaping Approaches to Quantum Computing

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

Debabrata Goswami

2003-01-01

216

An introduction to reliable quantum computation

This is an introduction to software methods of quantum fault tolerance. Broadly speaking, these methods describe strategies for using the noisy hardware components of a quantum computer to perform computations while continually monitoring and actively correcting the hardware faults. We discuss parallels and differences with similar methods for ordinary digital computation, we discuss some of the noise models used in designing and analyzing noisy quantum circuits, and we sketch the logic of some of the central results in this area of research.

Aliferis, Panos

2011-01-01

217

Computational Depth Complexity of Measurement-Based Quantum Computation

We prove that one-way quantum computations have the same computational power\\u000aas quantum circuits with unbounded fan-out. It demonstrates that the one-way\\u000amodel is not only one of the most promising models of physical realisation, but\\u000aalso a very powerful model of quantum computation. It confirms and completes\\u000aprevious results which have pointed out, for some specific problems, a depth

Dan E. Browne; Elham Kashefi; Simon Perdrix

2010-01-01

218

Computational depth complexity of measurement-based quantum computation

We prove that one-way quantum computations have the same computational power as quantum circuits with unbounded fan-out. It demonstrates that the one-way model is not only one of the most promising models of physical realisation, but also a very powerful model of quantum computation. It confirms and completes previous results which have pointed out, for some specific problems, a depth

Dan E. Browne; Elham Kashefi; Simon Perdrix

2009-01-01

219

Mathematical modeling of quantum noise and the quality of hardware components of quantum computers

In the present paper methods and algorithms of modeling quantum operations for quantum computer integrated circuits design are developed. We examine different ways of quantum operation descriptions, including operator-sums, unitary representations, Choi-Jamiolkowski state representations and the corresponding chi-matrices, as well as quantum system evolution operators. The results of modeling of practically important quantum gates: SQiSW (square root of i-SWAP gate), controlled-NOT (CNOT), and controlled Z-transform (CZ) subject to different decoherence mechanisms are presented. These mechanisms include analysis of depolarizing quantum noise and processes of amplitude and phase relaxation. Finally, we consider error correction of phase flip, and the tasks of creating and maintaining the entanglement, as well as its breaking for two- and multi-qubit realizations of quantum operations. Importance of the present analysis for the quality and efficiency of quantum information technologies in practical applications is discussed.

Yu. I. Bogdanov; A. Yu. Chernyavskiy; A. S. Holevo; V. F. Luckichev; S. A. Nuyanzin; A. A. Orlikovsky

2012-07-13

220

Prospects for quantum computation with trapped ions

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.

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

1997-12-31

221

Quantum Computational Logics and Possible Applications

NASA Astrophysics Data System (ADS)

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).

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

2008-01-01

222

The one-way quantum computer--a non-network model of quantum computation

A one-way quantum computer works by only performing a sequence of one-qubit measurements on a particular entangled multi-qubit state, the cluster state. No non-local operations are required in the process of computation. Any quantum logic network can be simulated on the one-way quantum computer. On the other hand, the network model of quantum computation cannot explain all ways of processing

Robert Raussendorf; Daniel E. Browne; Hans J. Briegel

2002-01-01

223

Cooling Technology for Electronic Computers

NASA Astrophysics Data System (ADS)

The rapid growth of data processing speed in computers has been sustained by the advances in cooling technology. This article first presents a review of the published data of heat loads in recent Japanese large-scale computers. The survey indicates that, since around 1980, the high-level integration of microelectronic circuits has brought about almost four fold increase in the power dissipation from logic chips. The integration also has invited the evolutions of multichip modules and new schemes of electronic interconnections. Forced convection air-cooling and liquid cooling coupled with thermal connectors are discussed with reference to the designs employed in actual computers. More advanced cooling schemes are also discussed. Finally, the importance of thermal environmental control of computer rooms is emphasized.

Nakayama, Wataru

224

The Heisenberg representation of quantum computers

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.

Gottesman, D.

1998-06-24

225

Center for Advanced Computational Technology

NASA Technical Reports Server (NTRS)

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.

Noor, Ahmed K.

2000-01-01

226

Efficient Simulation of Quantum Systems by Quantum Computers

We show that the time evolution of the wave function of a quantum mechanical many particle system can be implemented very efficiently on a quantum computer. The computational cost of such a simulation is comparable to the cost of a conventional simulation of the corresponding classical system. We then sketch how results of interest, like the energy spectrum of a

Christof Zalka

1998-01-01

227

PREFACE: Quantum Information, Communication, Computation and Cryptography

NASA Astrophysics Data System (ADS)

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.

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

2007-07-01

228

The one-way quantum computer - a non-network model of quantum computation

A one-way quantum computer works by only performing a sequence of one-qubit measurements on a particular entangled multi-qubit state, the cluster state. No non-local operations are required in the process of computation. Any quantum logic network can be simulated on the one-way quantum computer. On the other hand, the network model of quantum computation cannot explain all ways of processing quantum information possible with the one-way quantum computer. In this paper, two examples of the non-network character of the one-way quantum computer are given. First, circuits in the Clifford group can be performed in a single time step. Second, the realisation of a particular circuit --the bit-reversal gate-- on the one-way quantum computer has no network interpretation. (Submitted to J. Mod. Opt, Gdansk ESF QIT conference issue.)

Raussendorf, R; Briegel, H J; Raussendorf, Robert; Browne, Daniel E.; Briegel, Hans J.

2001-01-01

229

Efficient Quantum Computing of Complex Dynamics

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

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

2001-01-01

230

Quantum Computations with Cold Trapped Ions

A quantum computer can be implemented with cold ions confined in a linear trap and interacting with laser beams. Quantum gates involving any pair, triplet, or subset of ions can be realized by coupling the ions through the collective quantized motion. In this system decoherence is negligible, and the measurement (readout of the quantum register) can be carried out with

J. I. Cirac; P. Zoller

1995-01-01

231

Quantum Computer Games: Schrodinger Cat and Hounds

ERIC Educational Resources Information Center

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…

Gordon, Michal; Gordon, Goren

2012-01-01

232

Quantum and classical dynamics in adiabatic computation

NASA Astrophysics Data System (ADS)

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 revealing—though inconclusive—results.

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

2014-10-01

233

Quantum and Classical in Adiabatic Computation

Adiabatic transport provides a powerful way to manipulate quantum states. By preparing a system in a readily initialised 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 groundstate 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 optimisation algorithms and quantum adiabatic optimisation. This new 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 revealing - though inconclusive - results.

P. J. D. Crowley; T. Duric; W. Vinci; P. A. Warburton; A. G. Green

2014-05-20

234

A Realizable Distributed Ion-Trap Quantum Computer

Recent advances in trapped ion technology have rapidly accelerated efforts to construct a near-term, scalable quantum computer. Micro-machined electrodes in silicon are expected to trap hundreds of ions, each representing quantum bits, on a single chip. We find, however, that scalable systems must be composed of multiple chips and we explore inter-chip communication tech- nologies. Specifically, we explore the parallelization

Darshan D. Thaker; Tzvetan S. Metodi; Frederic T. Chong

2006-01-01

235

Adiabatic Quantum Computation: Coherent Control Back Action

Though attractive from scalability aspects, optical approaches to quantum computing are highly prone to decoherence and rapid population loss due to nonradiative processes such as vibrational redistribution. We show that such effects can be reduced by adiabatic coherent control, in which quantum interference between multiple excitation pathways is used to cancel coupling to the unwanted, non-radiative channels. We focus on experimentally demonstrated adiabatic controlled population transfer experiments wherein the details on the coherence aspects are yet to be explored theoretically but are important for quantum computation. Such quantum computing schemes also form a back-action connection to coherent control developments. PMID:23788822

Goswami, Debabrata

2013-01-01

236

Exponential rise of dynamical complexity in quantum computing through projections

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

237

Quantum computing. Defining and detecting quantum speedup.

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

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

2014-07-25

238

Fault-tolerant holonomic quantum computation

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.

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

2009-02-20

239

On Quantum Computation Theory Wim van Dam

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: 90Â5776Â091Â6 #12;" . . . Many errors have been made in the world which today

ten Cate, Balder

240

Superconducting quantum computation with imperfect resources

In this thesis, we address some important problems in current research in super-conducting quantum computation. We first describe how a quantum computer can be constructed using the rf-SQUID as the qubit, which was first proposed by us. We explain how the \\

Xingxiang Zhou

2002-01-01

241

Secure Entanglement Distillation for Double-Server Blind Quantum Computation

NASA Astrophysics Data System (ADS)

Blind quantum computation is a new secure quantum computing protocol where a client, who does not have enough quantum technologies at her disposal, can delegate her quantum computation to a server, who has a fully fledged quantum computer, in such a way that the server cannot learn anything about the client’s input, output, and program. If the client interacts with only a single server, the client has to have some minimum quantum power, such as the ability of emitting randomly rotated single-qubit states or the ability of measuring states. If the client interacts with two servers who share Bell pairs but cannot communicate with each other, the client can be completely classical. For such a double-server scheme, two servers have to share clean Bell pairs, and therefore the entanglement distillation is necessary in a realistic noisy environment. In this Letter, we show that it is possible to perform entanglement distillation in the double-server scheme without degrading the security of blind quantum computing.

Morimae, Tomoyuki; Fujii, Keisuke

2013-07-01

242

Monte Carlo Simulation of Quantum Computation

The many-body dynamics of a quantum computer can be reduced to the time evolution of non-interacting quantum bits in auxiliary fields by use of the Hubbard-Stratonovich representation of two-bit quantum gates in terms of one-bit gates. This makes it possible to perform the stochastic simulation of a quantum algorithm, based on the Monte Carlo evaluation of an integral of dimension polynomial in the number of quantum bits. As an example, the simulation of the quantum circuit for the Fast Fourier Transform is discussed.

N. J. Cerf; S. E. Koonin

1997-03-26

243

Geometry of quantum computation with qudits.

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

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

2014-01-01

244

Effects of Static Imperfections for Quantum Computing

We model the quantum computer hardware as a two-dimensional lattice of qubits with static imperfections, i.e. fluctuations in individual qubit energies and residual short-range inter-qubit couplings. We show that these imperfections can lead to the emergence of quantum chaos and dynamical thermalization also in a quantum computer ideally decoupled from the environment. We discuss their effect on the stability of

Giuliano Benenti; Giulio Casati

2003-01-01

245

Quantum Computation and Quantum Spin Dynamics Hans De Raedt, Kristel Michielsen, and Anthony Hams

quantum computers by simulating quantum spin models representing quantum computer hardware. ExamplesQuantum Computation and Quantum Spin Dynamics Hans De Raedt, Kristel Michielsen, and Anthony Hams@yuragi.t.u-tokyo.ac.jp, saitoh@spin.t.u-tokyo.ac.jp We analyze the stability of quantum computations on physically realiz- able

246

Efficient Simulation of Quantum Systems by Quantum Computers

We show that the time evolution of the wave function of a quantum mechanical many particle system can be implemented very efficiently on a quantum computer. The computational cost of such a simulation is comparable to the cost of a conventional simulation of the corresponding classical system. We then sketch how results of interest, like the energy spectrum of a system, can be obtained. We also indicate that ultimately the simulation of quantum field theory might be possible on large quantum computers. We want to demonstrate that in principle various interesting things can be done. Actual applications will have to be worked out in detail also depending on what kind of quantum computer may be available one day...

Christof Zalka

1996-03-25

247

Transitions in the quantum computational power

NASA Astrophysics Data System (ADS)

We construct two spin models on lattices (both two and three dimensional) to study the capability of quantum computational power as a function of temperature and the system parameter. There exists a finite region in the phase diagram such that the thermal equilibrium states are capable of providing a universal fault-tolerant resource for measurement-based quantum computation. Moreover, in such a region the thermal resource states on the three-dimensional lattices can enable topological protection for quantum computation. The two models behave similarly in terms of quantum computational power. However, they have different properties in terms of the usual phase transitions. The first model has a first-order phase transition only at zero temperature whereas there is no transition at all in the second model. Interestingly, the transition in the quantum computational power does not coincide with the phase transition in the first model.

Wei, Tzu-Chieh; Li, Ying; Kwek, Leong Chuan

2014-05-01

248

Transitions in the quantum computational power

We construct two spin models on lattices (both two and three-dimensional) to study the capability of quantum computational power as a function of temperature and the system parameter. There exists a finite region in the phase diagram such that the thermal equilibrium states are capable of providing a universal fault-tolerant resource for measurement-based quantum computation. Moreover, in such a region the thermal resource states on the 3D lattices can enable topological protection for quantum computation. The two models behave similarly in terms of quantum computational power. However, they have different properties in terms of the usual phase transitions. The first model has a first-order phase transition only at zero temperature whereas there is no transition at all in the second model. Interestingly, the transition in the quantum computational power does not coincide with the phase transition in the first model.

Tzu-Chieh Wei; Ying Li; Leong Chuan Kwek

2014-05-16

249

Infinite possibilities: Computational structures technology

NASA Technical Reports Server (NTRS)

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.

Beam, Sherilee F.

1994-01-01

250

Infinite possibilities: Computational structures technology

NASA Astrophysics Data System (ADS)

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.

Beam, Sherilee F.

1994-12-01

251

The one-way quantum computer--a non-network model of quantum computation

A one-way quantum computer (QCC) works by performing a sequence of one-qubit measurements on a particular entangled multi-qubit state, the cluster state. No non-local operations are required in the process of computation. Any quantum logic network can be simulated on the QCC. On the other hand, the network model of quantum computation cannot explain all ways of processing quantum information

Robert Raussendorf; Daniel E. Browne; Hans J. Briegel

2002-01-01

252

Quantum dot-based quantum buses for quantum computer hardware architecture

We propose a quantum bus based on semiconductor self-assembled quantum dots. This allows for transmission of qubits between the different quantum registers, and could be integrated in most of the present proposal for semiconductor quantum dot-based quantum computation.

Irene D’Amico

2006-01-01

253

From transistor to trapped-ion computers for quantum chemistry.

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. PMID:24395054

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

2014-01-01

254

Secure Multi-party Quantum Computing

Secure multi-party computing, also called "secure function evaluation", has been extensively studied in classical cryptography. We consider the extension of this task to computation with quantum inputs and circuits. Our protocols are information-theoretically secure, i.e. no assumptions are made on the computational power of the adversary. For the 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 show how to perform any multi-party quantum computation as long as the number of dishonest players is less than n/6.

Claude Crepeau; Daniel Gottesman; Adam Smith

2002-06-20

255

Recent Results in Photonic Quantum Computations, Simulations and Quantum Networks

NASA Astrophysics Data System (ADS)

The applications of photonic entanglement manifold and reach from quantum communication [1] to quantum metrology [2] and optical quantum computing [3]. The advantage of the photon's mobility makes optical quantum computing unprecedented in speed, including feed-forward operations with high fidelity [4]. During the last few years the degree of control over photonic multi-particle entanglement has improved substantially and allows for not only overcoming the random nature of spontaneous emission sources [5], but also for the quantum simulation of other quantum systems. Here, I will also present the simulation of four spin-1/2 particles interacting via any Heisenberg-type Hamiltonian [6]. Moreover, recent experimental and theoretical progress, using the concepts of measurement-based quantum computation, indicates that photons are best suited for quantum networks. I will also present present results for the realization for such a client-server environment, where quantum information is communicated and computed using the same physical system [7]. References: [1] PRL 103, 020503 (2009); [2] Nature 429, 158 (2004); [3] Nature 434, 169 (2005); [4] Nature 445, 65 (2007); [5] Nature Photon 4, 553 (2010); [6] Nature Physics 7, 399 (2011); [7] in press.

Walther, Philip

2012-02-01

256

Quantum computing and the entanglement frontier

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.

John Preskill

2012-03-26

257

Quantum computing and the entanglement frontier

NASA Astrophysics Data System (ADS)

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.

Preskill, John

2013-04-01

258

KLM quantum computation with bosonic atoms

A Knill-Laflamme-Milburn (KLM) type quantum computation with bosonic neutral atoms or bosonic ions is suggested. Crucially, as opposite to other quantum computation schemes involving atoms (ions), no controlled interactions between atoms (ions) involving their internal levels are required. Versus photonic KLM computation this scheme has the advantage that single atom (ion) sources are more natural than single photon sources, and single atom (ion) detectors are far more efficient than single photon ones.

Sandu Popescu

2006-10-06

259

Computational depth complexity of measurement-based quantum computation

We prove that one-way quantum computations have the same computational power as quantum circuits with unbounded fan-out. It demonstrates that the one-way model is not only one of the most promising models of physical realisation, but also a very powerful model of quantum computation. It confirms and completes previous results which have pointed out, for some specific problems, a depth separation between the one-way model and the quantum circuit model. Since one-way model has the same computational power as unbounded quantum fan-out circuits, the quantum Fourier transform can be approximated in constant depth in the one-way model, and thus the factorisation can be done by a polytime probabilistic classical algorithm which has access to a constant-depth one-way quantum computer. The extra power of the one-way model, comparing with the quantum circuit model, comes from its classical-quantum hybrid nature. We show that this extra power is reduced to the capability to perform unbounded classical parity gates in co...

Browne, Dan E; Perdrix, Simon

2009-01-01

260

Computer technologies and institutional memory

NASA Technical Reports Server (NTRS)

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.

Bell, Christopher; Lachman, Roy

1989-01-01

261

Resilient Quantum Computation: Error Models and Thresholds

Recent research has demonstrated that quantum computers can solve certain types of problems substantially faster than the known classical algorithms. These problems include factoring integers and certain physics simulations. Practical quantum computation requires overcoming the problems of environmental noise and operational errors, problems which appear to be much more severe than in classical computation due to the inherent fragility of quantum superpositions involving many degrees of freedom. Here we show that arbitrarily accurate quantum computations are possible provided that the error per operation is below a threshold value. The result is obtained by combining quantum error-correction, fault tolerant state recovery, fault tolerant encoding of operations and concatenation. It holds under physically realistic assumptions on the errors.

Emanuel Knill; Raymond Laflamme; Wojciech H. Zurek

1997-02-26

262

Teaching with technology: computer basics.

In this bimonthly series, the author examines how nurse educators can use Internet and Web-based computer technologies such as search, communication, and collaborative writing tools, social networking and social bookmarking sites, virtual worlds, and Web-based teaching and learning programs. This article describes approaches to finding information on the Web. Web-based search tools including Internet search engines, organizational databases, and those at the library will be discussed. Techniques to evaluate the validity, usefulness, and applicability of search outcomes are included. PMID:19104333

Wink, Diane

2009-01-01

263

Quantum well photoconductors in infrared detector technology

The paper compares the achievements of quantum well infrared photodetector (QWIP) technology with those of competitive technologies, with the emphasis on the material properties, device structure, and their impact on focal plane array (FPA) performance. Special attention is paid to two competitive technologies, QWIP and HgCdTe, in the long-wavelength IR (LWIR) and very-long-wavelength IR (VLWIR) spectral ranges. Because so far,

A. Rogalski

2003-01-01

264

Fault-tolerant, Universal Adiabatic Quantum Computation

Quantum computation has revolutionary potential for speeding computational tasks such as factoring and simulating quantum systems, but the task of constructing a quantum computer is daunting. Adiabatic quantum computation and other ``hands-off" approaches relieve the need for rapid, precise pulsing to control the system, inspiring at least one high-profile effort to realize a hands-off quantum computing device. But is hands-off incompatible with fault-tolerant? Concerted effort and many innovative ideas have not resolved this question but have instead deepened it, linking it to fundamental problems in quantum complexity theory. Here we present a hands-off approach that is provably (a) capable of scalable universal quantum computation in a non-degenerate ground state and (b) fault-tolerant against an analogue of the usual local stochastic fault model. A satisfying physical and numerical argument indicates that (c) it is also fault-tolerant against thermal excitation below a threshold temperature independent of the computation size.

Ari Mizel

2014-03-30

265

LDRD final report on quantum computing using interacting semiconductor quantum wires.

For several years now quantum computing has been viewed as a new paradigm for certain computing applications. Of particular importance to this burgeoning field is the development of an algorithm for factoring large numbers which obviously has deep implications for cryptography and national security. Implementation of these theoretical ideas faces extraordinary challenges in preparing and manipulating quantum states. The quantum transport group at Sandia has demonstrated world-leading, unique double quantum wires devices where we have unprecedented control over the coupling strength, number of 1 D channels, overlap and interaction strength in this nanoelectronic system. In this project, we study 1D-1D tunneling with the ultimate aim of preparing and detecting quantum states of the coupled wires. In a region of strong tunneling, electrons can coherently oscillate from one wire to the other. By controlling the velocity of the electrons, length of the coupling region and tunneling strength we will attempt to observe tunneling oscillations. This first step is critical for further development double quantum wires into the basic building block for a quantum computer, and indeed for other coupled nanoelectronic devices that will rely on coherent transport. If successful, this project will have important implications for nanoelectronics, quantum computing and information technology.

Lyo, Sungkwun Kenneth; Dunn, Roberto G.; Lilly, Michael Patrick; Tibbetts, Denise R. (.; )); Stephenson, Larry L.; Seamons, John Andrew; Reno, John Louis; Bielejec, Edward Salvador; Simmons, Jerry Alvon

2006-01-01

266

Numerical computation for teaching quantum statistics

NASA Astrophysics Data System (ADS)

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.

Price, Tyson; Swendsen, Robert H.

2013-11-01

267

Application of superconducting quantum interferometer in quantum computer development

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

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

2008-01-01

268

One-way quantum computation with circuit quantum electrodynamics

In this Brief Report, we propose a potential scheme to implement one-way quantum computation with circuit quantum electrodynamics (QED). Large cluster states of charge qubits can be generated in just one step with a superconducting transmission line resonator (TLR) playing the role of a dispersive coupler. A single-qubit measurement in the arbitrary basis can be implemented using a single electron

Chun-Wang Wu; Yang Han; Xiao-Jun Zhong; Ping-Xing Chen; Cheng-Zu Li

2010-01-01

269

Effective Pure States for Bulk Quantum Computation

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

Emanuel Knill; Isaac Chuang; Raymond Laflamme

1997-06-24

270

Efficient Simulation of Quantum Systems by Quantum Computers

We show that the time evolution of the wave function of a quantum mechanical\\u000amany particle system can be implemented very efficiently on a quantum computer.\\u000aThe computational cost of such a simulation is comparable to the cost of a\\u000aconventional simulation of the corresponding classical system. We then sketch\\u000ahow results of interest, like the energy spectrum of a

Christof Zalka

1996-01-01

271

Parallel quantum computer simulation on the GPU

Simulation of quantum computers using classical computers is a hard problem with high memory and computa- tional requirements. Parallelization can alleviate this problem, allowing the simulation of more qubits at the same time or the same number of qubits to be simulated in less time. A promising approach is to exploit the high performance computing capa- bilities provided by the

Andrei Amariutei; Simona Caraiman

2011-01-01

272

A Lambda Calculus for Quantum Computation

The classical lambda calculus may be regarded both as a programming language and as a formal algebraic system for reasoning about com- putation. It provides a computational model equivalent to the Turing machine, and continues to be of enormous benefit in the classical the- ory of computation. We propose that quantum computation, like its classical counterpart, may benefit from a

André Van Tonder

2003-01-01

273

Hybrid optomechanics for Quantum Technologies

We review the physics of hybrid optomechanical systems consisting of a mechanical oscillator interacting with both a radiation mode and an additional matter-like system. We concentrate on the cases embodied by either a single or a multi-atom system (a Bose-Einstein condensate, in particular) and discuss a wide range of physical effects, from passive mechanical cooling to the set-up of multipartite entanglement, from optomechanical non-locality to the achievement of non-classical states of a single mechanical mode. The reviewed material showcases the viability of hybridised cavity optomechanical systems as basic building blocks for quantum communication networks and quantum state-engineering devices, possibly empowered by the use of quantum and optimal control techniques. The results that we discuss are instrumental to the promotion of hybrid optomechanical devices as promising experimental platforms for the study of non-classicality at the genuine mesoscopic level.

Benjamin Rogers; Nicola Lo Gullo; Gabriele De Chiara; G. Massimo Palma; Mauro Paternostro

2014-02-05

274

Hybrid optomechanics for Quantum Technologies

NASA Astrophysics Data System (ADS)

We review the physics of hybrid optomechanical systems consisting of a mechanical oscillator interacting with both a radiation mode and an additional matterlike system. We concentrate on the cases embodied by either a single or a multi-atom system (a Bose-Einstein condensate, in particular) and discuss a wide range of physical effects, from passive mechanical cooling to the set-up of multipartite entanglement, from optomechanical nonlocality to the achievement of non-classical states of a single mechanical mode. The reviewed material showcases the viability of hybridised cavity optomechanical systems as basic building blocks for quantum communication networks and quantum state-engineering devices, possibly empowered by the use of quantum and optimal control techniques. The results that we discuss are instrumental to the promotion of hybrid optomechanical devices as promising experimental platforms for the study of nonclassicality at the genuine mesoscopic level.

Rogers, B.; Lo Gullo, N.; De Chiara, G.; Palma, G. M.; Paternostro, M.

2014-06-01

275

Quantum Computation and Shor's Factoring Algorithm Ronald de Wolf

that are based on quantumÂ mechanical principles. We give a brief introduction to the model of quantum the computational power and other properÂ ties of computers based on quantumÂmechanical principles. Its main with an abstract explanation of quantum mechanics in Section 2. Section 3 explains what quantum bits and quantum

de Wolf, Ronald

276

Parallelization of a fuzzy control algorithm using quantum computation

Quantum computation is proposed for the parallelization of a fuzzy logic control (FLC) algorithm. Quantum computation speeds up the fuzzy inference since serial operations between matrices of large dimensionality are now replaced by a one-step quantum addition or a quantum subtraction. The unitarity properties of the algorithm prove that the FLC stands for a simulator of a quantum computing machine.

Gerasimos G. Rigatos; Spyros G. Tzafestas

2002-01-01

277

One-way quantum computation with circuit quantum electrodynamics

NASA Astrophysics Data System (ADS)

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

Wu, Chun-Wang; Han, Yang; Zhong, Xiao-Jun; Chen, Ping-Xing; Li, Cheng-Zu

2010-03-01

278

Hyper-parallel photonic quantum computation with coupled quantum dots

NASA Astrophysics Data System (ADS)

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

Ren, Bao-Cang; Deng, Fu-Guo

2014-04-01

279

Hyper-parallel photonic quantum computation with coupled quantum dots

It is well known that a parallel quantum computer is more powerful than a classical one. So far, there are some important works about the construction of universal quantum logic gates, the key elements in quantum computation. However, they are focused on operating on one degree of freedom (DOF) of quantum systems. Here, we investigate the possibility of achieving scalable hyper-parallel quantum computation based on two DOFs of photon systems. We construct a deterministic hyper-controlled-not (hyper-CNOT) gate operating on both the spatial-mode and the polarization DOFs of a two-photon system simultaneously, by exploiting the giant optical circular birefringence induced by quantum-dot spins in double-sided optical microcavities as a result of cavity quantum electrodynamics (QED). This hyper-CNOT gate is implemented by manipulating the four qubits in the two DOFs of a two-photon system without auxiliary spatial modes or polarization modes. It reduces the operation time and the resources consumed in quantum information processing, and it is more robust against the photonic dissipation noise, compared with the integration of several cascaded CNOT gates in one DOF. PMID:24721781

Ren, Bao-Cang; Deng, Fu-Guo

2014-01-01

280

Progress in silicon-based quantum computing.

We review progress at the Australian Centre for Quantum Computer Technology towards the fabrication and demonstration of spin qubits and charge qubits based on phosphorus donor atoms embedded in intrinsic silicon. Fabrication is being pursued via two complementary pathways: a 'top-down' approach for near-term production of few-qubit demonstration devices and a 'bottom-up' approach for large-scale qubit arrays with sub-nanometre precision. The 'top-down' approach employs a low-energy (keV) ion beam to implant the phosphorus atoms. Single-atom control during implantation is achieved by monitoring on-chip detector electrodes, integrated within the device structure. In contrast, the 'bottom-up' approach uses scanning tunnelling microscope lithography and epitaxial silicon overgrowth to construct devices at an atomic scale. In both cases, surface electrodes control the qubit using voltage pulses, and dual single-electron transistors operating near the quantum limit provide fast read-out with spurious-signal rejection. PMID:12869321

Clark, R G; Brenner, R; Buehler, T M; Chan, V; Curson, N J; Dzurak, A S; Gauja, E; Goan, H S; Greentree, A D; Hallam, T; Hamilton, A R; Hollenberg, L C L; Jamieson, D N; McCallum, J C; Milburn, G J; O'Brien, J L; Oberbeck, L; Pakes, C I; Prawer, S D; Reilly, D J; Ruess, F J; Schofield, S R; Simmons, M Y; Stanley, F E; Starrett, R P; Wellard, C; Yang, C

2003-07-15

281

Directional Coupling for Quantum Computing and Communication

NASA Astrophysics Data System (ADS)

We introduce the concept of directional coupling, i.e., the selective transfer of a state between adjacent quantum wires, in the context of quantum computing and communication. Our analysis rests upon a mathematical analogy between a dual-channel directional coupler and a composite spin system.

Nikolopoulos, Georgios M.

2008-11-01

282

Is the Brain a Quantum Computer?

ERIC Educational Resources Information Center

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…

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

2006-01-01

283

Temporal resources for global quantum computing architectures

Using the methods for optimal simulation of quantum logic gates, we perform a quantitative estimation of the time resources involved in the execution of universal gate sets for the case of three representative models of quantum computation based on global control. The importance of such models stems from the solution to the problem of experimentally addressing and locally manipulating the

Juan D. Jaramillo; John H. Reina

2008-01-01

284

QDENSITY - A Mathematica Quantum Computer simulation

This Mathematica 5.2 package 1 is a simulation of a Quantum Computer. The pro- gram provides a modular, instructive approach for generating the basic elements that make up a quantum circuit. The main emphasis is on using the density ma- trix, although an approach using state vectors is also implemented in the package. The package commands are defined in Qdensity.m

Bruno Juliá-Díaz; Joseph M. Burdis; Frank Tabakin

2006-01-01

285

Quantum computation with optical coherent states

We show that quantum computation circuits using coherent states as the logical qubits can be constructed from simple linear networks, conditional photon measurements and "small" coherent superposition resource states.

T. C. Ralph; A. Gilchrist; G. J. Milburn; W. J. Munro; S. Glancy

2003-06-01

286

Efficient Quantum Computation using Coherent States

Universal quantum computation using optical coherent states is studied. A teleportation scheme for a coherent-state qubit is developed and applied to gate operations. This scheme is shown to be robust to detection inefficiency.

H. Jeong; M. S. Kim

2001-09-17

287

Advanced laptop and small personal computer technology

NASA Technical Reports Server (NTRS)

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.

Johnson, Roger L.

1991-01-01

288

Review of cooling technologies for computer products

This paper provides a broad review of the cooling technologies for computer products from desktop computers to large servers. For many years cooling technology has played a key role in enabling and facilitating the packaging and performance improvements in each new generation of computers. The role of internal and external thermal resistance in module level cooling is discussed in terms

Richard C. Chu; Robert E. Simons; Michael J. Ellsworth; Roger R. Schmidt; Vincent Cozzolino

2004-01-01

289

Stabilization of Quantum Computations by Symmetrization

We propose a method for the stabilization of quantum computations (including quan- tum state storage). The method is based on the operation of projection intoSYM, the symmetric subspace of the full state space of R redundant copies of the computer. We describe an ecient algorithm and quantum network eectingSYM{projection and discuss the stabilizing eect of the proposed method in the

Adriano Barenco; Andre? Berthiaume; David Deutsch; Artur Ekert; Richard Jozsa; Chiara Macchiavello

1997-01-01

290

Quantum computing algorithm for electromagnetic field simulation

Quantum computing offers new concepts for the simulation of complex physical systems. A quantum computing algorithm for electromagnetic\\u000a field simulation is presented here. The electromagnetic field simulation is performed on the basis of the Transmission Line\\u000a Matrix (TLM) method. The Hilbert space formulation of TLM allows us to obtain a time evolution operator for the TLM method,\\u000a which can then

Siddhartha Sinha; Peter Russer

2010-01-01

291

Center for Computational Structures Technology

NASA Technical Reports Server (NTRS)

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.

Noor, Ahmed K.; Perry, Ferman W.

1995-01-01

292

Measurement-based quantum computation on cluster states

We give a detailed account of the one-way quantum computer, a scheme of quantum computation that consists entirely of one-qubit measurements on a particular class of entangled states, the cluster states. We prove its universality, describe why its underlying computational model is different from the network model of quantum computation, and relate quantum algorithms to mathematical graphs. Further we investigate

Robert Raussendorf; Daniel E. Browne; Hans J. Briegel

2003-01-01

293

Acausal measurement-based quantum computing

NASA Astrophysics Data System (ADS)

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.

Morimae, Tomoyuki

2014-07-01

294

Simulation and verification II: simulating quantum computing: quantum express

Quantum Computing (QC) research has gained a lot of momentum recently due to several theoretical analyses that indicate that QC is significantly more efficient at solving certain classes of problems than classical computing. While experimental validation will ultimately be required, the primitive nature of current QC hardware leaves practical testing limited to trivial examples. Thus, a robust simulator is needed

Kareem S. Aggour; Renee Guhde; Melvin K. Simmons; Michael J. Simon

2003-01-01

295

Twisted Graph States for Ancilla-driven Universal Quantum Computation

We introduce a new paradigm for quantum computing called Ancilla-Driven Quantum Computation (ADQC) which combines aspects both of the quantum circuit [D. Deutsch. Quantum computational networks. Proc. Roy. Soc. Lond A, 425, 1989] and the one-way model [R. Raussendorf and H. J. Briegel. A one-way quantum computer. Physical Review Letters, 86, 2001] to overcome challenging issues in building large-scale quantum

E. Kashefi; D. K. L. Oi; D. Browne; J. Anders; E. Andersson

2009-01-01

296

EDITORIAL: Quantum Computing and the Feynman Festival

NASA Astrophysics Data System (ADS)

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.

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

2003-12-01

297

Quantum Computation as a Dynamical Process

In this paper, we discuss the dynamical issues of quantum computation. We demonstrate that fast wave function oscillations can affect the performance of Shor's quantum algorithm by destroying required quantum interference. We also show that this destructive effect can be routinely avoided by using resonant-pulse techniques. We discuss the dynamics of resonant pulse implementations of quantum logic gates in Ising spin systems. We also discuss the influence of non-resonant excitations. We calculate the range of parameters where undesirable non-resonant effects can be minimized. Finally, we describe the ``$2\\pi k$-method'' which avoids the detrimental deflection of non-resonant qubits.

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

1999-04-29

298

Brain-Computer Interfaces and Quantum Robots

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 qu...

Pessa, Eliano

2009-01-01

299

Computational Depth Complexity of Measurement-Based Quantum Computation

NASA Astrophysics Data System (ADS)

In this paper, we mainly prove that the "depth of computations" in the one-way model is equivalent, up to a classical side-processing of logarithmic depth, to the quantum circuit model augmented with unbounded fanout gates. It demonstrates that the one-way model is not only one of the most promising models of physical realisation, but also a very powerful model of quantum computation. It confirms and completes previous results which have pointed out, for some specific problems, a depth separation between the one-way model and the quantum circuit model. Since one-way model has the same parallel power as unbounded quantum fan-out circuits, the quantum Fourier transform can be approximated in constant depth in the one-way model, and thus the factorisation can be done by a polytime probabilistic classical algorithm which has access to a constant-depth one-way quantum computer. The extra power of the one-way model, comparing with the quantum circuit model, comes from its classical-quantum hybrid nature. We show that this extra power is reduced to the capability to perform unbounded classical parity gates in constant depth.

Browne, Dan; Kashefi, Elham; Perdrix, Simon

300

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.

Hai-Rui Wei; Fu-Guo Deng

2014-12-12

301

NASA Astrophysics Data System (ADS)

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.

Wei, Hai-Rui; Deng, Fu-Guo

2014-12-01

302

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

Wei, Hai-Rui; Deng, Fu-Guo

2014-01-01

303

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

Wei, Hai-Rui; Deng, Fu-Guo

2014-01-01

304

Computer Technology: State of the Art.

ERIC Educational Resources Information Center

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)

Withington, Frederic G.

1981-01-01

305

Disruptive technology business models in cloud computing

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 ...

Krikos, Alexis Christopher

2010-01-01

306

Revisiting the hopes for scalable quantum computation

NASA Astrophysics Data System (ADS)

The hopes for scalable quantum computing rely on the "threshold theorem": once the error per qubit per gate is below a certain value, the methods of quantum error correction allow indefinitely long quantum computations. The proof is based on a number of assumptions, which are supposed to be satisfied exactly, like axioms, e.g., zero undesired interactions between qubits, etc. However, in the physical world no continuous quantity can be exactly zero, it can only be more or less small. Thus the "error per qubit per gate" threshold must be complemented by the required precision with which each assumption should be fulfilled. In the absence of this crucial information, the prospects of scalable quantum computing remain uncertain.

Dyakonov, M. I.

2013-12-01

307

Prospects for quantum computing: Extremely doubtful

NASA Astrophysics Data System (ADS)

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

Dyakonov, M. I.

2014-09-01

308

Computing with RFID: Drivers, Technology and Implications

Computing with RFID: Drivers, Technology and Implications George Roussos School of Computer Science Frequency Identification or simply rfid has come to be an integral part of modern computing. Rfid is notable, we cater to the computing professional who is not familiar with the specifics of rfid which we

Roussos, George

309

Quantum Computing and Lie Theory Feynman's suggestion that the only effective way to model quantum phe- nomena on a computer would be to build a computer that made use of quantum mechanics was one of the cornerstones of the birth of quantum com- puting. In his later years he studied both classical and quantum

D'Agnolo, Andrea

310

Qubus ancilla-driven quantum computation

NASA Astrophysics Data System (ADS)

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.

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

2014-12-01

311

Computational complexity of the quantum separability problem

Ever since entanglement was identified as a computational and cryptographic resource, researchers have sought efficient ways to tell whether a givendensity matrix represents an unentangled, or separable, state. This paper gives the first systematic and com- prehensive treatment of this (bipartite) quantum separability problem, focusing on its deterministic (as opposed to randomized) computational complexity. First, I review the one-sided tests

Lawrence M. Ioannou

2006-01-01

312

Accelerating Quantum Computer Simulation via Parallel Eigenvector Computation

Quantum-dot cellular automata (QDCA) hold great potential to produce the next generation of computer hardware, but their development is hindered by computationally intensive simulations. Our research therefore focuses on rewriting one such simulation to run parallel calculations on a graphics processing unit (GPU). We have decreased execution time from 33 hours 11 minutes to 1 hour 39 minutes, but current

Karl Stathakis

2011-01-01

313

Efficient One-way Quantum Computations for Quantum Error Correction

We show how to explicitly construct an $O(nd)$ size and constant quantum depth circuit which encodes any given $n$-qubit stabilizer code with $d$ generators. Our construction is derived using the graphic description for stabilizer codes and the one-way quantum computation model. Our result demonstrates how to use cluster states as scalable resources for many multi-qubit entangled states and how to

Wei Huang; Zhaohui Wei

2007-01-01

314

Efficient one-way quantum computations for quantum error correction

We show how to explicitly construct an O(nd) size and constant quantum depth circuit which encodes any given n-qubit stabilizer code with d generators. Our construction is derived using the graphic description for stabilizer codes and the one-way quantum computation model. Our result demonstrates how to use cluster states as scalable resources for many multi-qubit entangled states and how to

Wei Huang; Zhaohui Wei

2009-01-01

315

Extending matchgates into universal quantum computation

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.

Brod, Daniel J.; Galvao, Ernesto F. [Instituto de Fisica, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza s/n, Gragoata, Niteroi, RJ, 24210-340 (Brazil)

2011-08-15

316

Quantum cryptographic network based on quantum memories Eli Biham Computer Science Department Quantum correlations between two particles show nonclassical properties that can be used for providing secure transmission of information. We present a quantum cryptographic system in which users store

Mor, Tal

317

Twisted graph states for ancilla-driven quantum computation

We introduce a new paradigm for quantum computing called Ancilla-Driven Quantum Computation (ADQC) combines aspects of the quantum circuit and the one-way model to overcome challenging issues in building large-scale quantum computers. Instead of directly manipulating each qubit to perform universal quantum logic gates or measurements, ADQC uses a fixed two-qubit interaction to couple the memory register of a quantum

Elham Kashefi; Daniel K. L. Oi; Janet Anders; Erika Andersson

2009-01-01

318

Quantum computing based on vibrational eigenstates: Pulse area theorem analysis

Quantum computing based on vibrational eigenstates: Pulse area theorem analysis Taiwang Cheng the accuracy of quantum gates in a quantum computer based on molecular vibrational eigenstates. The effects.1063/1.2164457 I. INTRODUCTION The field of quantum computing1Â3 has emerged as an intriguing and exciting new

Brown, Alex

319

INTRODUCTION TO QUANTUM INFORMATION AND COMPUTATION FOR CHEMISTRY

INTRODUCTION TO QUANTUM INFORMATION AND COMPUTATION FOR CHEMISTRY SABRE KAIS Department and Computation for Chemistry, First Edition. Edited by Sabre Kais. Â© 2014 John Wiley & Sons, Inc. Published 2014 results in quantum computation and quantum information, with potential applications in quantum chemistry

Kais, Sabre

320

Technical Report No. 2005500 Quantum computing: Beyond the limits of

to a quantum mechanical device was the elaboration of a model that should be abstracted away from an Canada EÂmail: fmarius,aklg@cs.queensu.ca July 22, 2005 Abstract The quantum model of computation context created by quantum mechanics, the computational power of a quantum computer is therefore strictly

Graham, Nick

321

Discrete Cosine Transforms on Quantum Computers Andreas Klappenecker

for a computer that takes advantage of quantum mechanical superposition, entanglement, and interference Introduction Feynman proposed in 1982 a computational model that was based on the principles of quantum physics is justified by the machine model introduced below. 1 #12; 3 Quantum Gates A quantum computer consists

Klappenecker, Andreas

322

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

quantum computation with one pure qubit (DQC1) is an efficient model of computation that uses highly mixed intrinsically quantum mechanical correlations and that these could offer a valuable resource for quantum deal of work has been done on the con- ventional pure-state models of quantum computing [1

White, Andrew G.

323

An Extension of Gleason's Theorem for Quantum Computation

We develop a synthesis of Turing's paradigm of computation and von Neumann's quantum logic to serve as a model for quantum computation with recursion, such that potentially non-terminating computation can take place, as in a quantum Turing machine. This model is based on the extension of von Neumann's quantum logic to partial states, defined here as sub-probability measures on the

Abbas Edalat

2004-01-01

324

Efficient quantum circuits for one-way quantum computing.

While Ising-type interactions are ideal for implementing controlled phase flip gates in one-way quantum computing, natural interactions between solid-state qubits are most often described by either the XY or the Heisenberg models. We show an efficient way of generating cluster states directly using either the imaginary SWAP (iSWAP) gate for the XY model, or the sqrt[SWAP] gate for the Heisenberg model. Our approach thus makes one-way quantum computing more feasible for solid-state devices. PMID:19392095

Tanamoto, Tetsufumi; Liu, Yu-Xi; Hu, Xuedong; Nori, Franco

2009-03-13

325

Efficient Quantum Circuits for One-Way Quantum Computing

NASA Astrophysics Data System (ADS)

While Ising-type interactions are ideal for implementing controlled phase flip gates in one-way quantum computing, natural interactions between solid-state qubits are most often described by either the XY or the Heisenberg models. We show an efficient way of generating cluster states directly using either the imaginary SWAP (iSWAP) gate for the XY model, or the SWAP gate for the Heisenberg model. Our approach thus makes one-way quantum computing more feasible for solid-state devices.

Tanamoto, Tetsufumi; Liu, Yu-Xi; Hu, Xuedong; Nori, Franco

2009-03-01

326

Persuasion Strategies for Computers as Persuasive Technologies

Similar to human persuaders in our society, persuasive computing technologies can influence people's attitudes and bring some constructive changes in many domains such as marketing, health, safety, environment and so on. Since the study of computers as persuasive technologies was introduced at CHI 97 as a new research area, more valuable studies have been done in this relatively unexplored area.

Ran Cheng

327

Prior Computer Experience and Technology Acceptance

ERIC Educational Resources Information Center

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…

Varma, Sonali

2010-01-01

328

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

Donsez, Didier

329

Liquid Crystal State NMR Quantum Computing - Characterization, Control and Certification.

??Quantum computers offer the possibility of solving some problems more efficiently than their classical counterparts. The current forerunner in the experimental demonstration of quantum algorithms… (more)

Trottier, Denis-Alexandre

2013-01-01

330

Fault-Tolerant Postselected Quantum Computation: Threshold Analysis

The schemes for fault-tolerant postselected quantum computation given in [Knill, Fault-Tolerant Postselected Quantum Computation: Schemes, http://arxiv.org/abs/quant-ph/0402171] are analyzed to determine their error-tolerance. The analysis is based on computer-assisted heuristics. It indicates that if classical and quantum communication delays are negligible, then scalable qubit-based quantum computation is possible with errors above 1% per elementary quantum gate.

E. Knill

2004-04-19

331

Biologically inspired path to quantum computer

NASA Astrophysics Data System (ADS)

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

Ogryzko, Vasily; Ozhigov, Yuri

2014-12-01

332

Defeating classical bit commitments with a quantum computer

It has been recently shown by Mayers that no bit commitment scheme is secure if the participants have unlimited computational power and technology. However it was noticed that a secure protocol could be obtained by forcing the cheater to perform a measurement. Similar situations had been encountered previously in the design of Quantum Oblivious Transfer. The question is whether a classical bit commitment could be used for this specific purpose. We demonstrate that, surprisingly, classical unconditionally concealing bit commitments do not help.

Gilles Brassard; Claude Crépeau; Dominic Mayers; Louis Salvail

1998-06-09

333

Free spin quantum computation with semiconductor nanostructures

Taking the excess electron spin in a unit cell of semiconductor multiple quantum-dot structure as a qubit, we can implement scalable quantum computation without resorting to spin-spin interactions. The technique of single electron tunnelings and the structure of quantum-dot cellular automata (QCA) are used to create a charge entangled state of two electrons which is then converted into spin entanglement states by using single spin rotations. Deterministic two-qubit quantum gates can also be manipulated using only single spin rotations with help of QCA. A single-short read-out of spin states can be realized by coupling the unit cell to a quantum point contact.

Wei-Min Zhang; Yin-Zhong Wu; Chopin Soo

2005-02-01

334

From Computer Lab to Technology Class.

ERIC Educational Resources Information Center

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…

Sherwood, Sandra

1999-01-01

335

Efficient quantum computing of complex dynamics.

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 significant than the errors of random noise in gate operations. PMID:11736427

Benenti, G; Casati, G; Montangero, S; Shepelyansky, D L

2001-11-26

336

Universal dephasing control during quantum computation

NASA Astrophysics Data System (ADS)

Dephasing is a ubiquitous phenomenon that leads to the loss of coherence in quantum systems and the corruption of quantum information. We present a universal dynamical control approach to combat dephasing during all stages of quantum computation, namely, storage and single- and two-qubit operators. We show that (a) tailoring multifrequency gate pulses to the dephasing dynamics can increase fidelity; (b) cross-dephasing, introduced by entanglement, can be eliminated by appropriate control fields; (c) counterintuitively and contrary to previous schemes, one can increase the gate duration, while simultaneously increasing the total gate fidelity.

Gordon, Goren; Kurizki, Gershon

2007-10-01

337

Computational quantum-classical boundary of commuting quantum circuits

It is often said that the transition from quantum to classical worlds is caused by decoherence originated from an interaction between a system of interest and its surrounding environment. Here we establish a computational quantum-classical boundary from the viewpoint of classical simulatability of a quantum system under decoherence. Specifically, we consider the commuting quantum circuits as dynamics of the quantum system. To show intractability of classical simulation above the boundary, we utilize the postselection argument introduced by M. J. Bremner, R. Jozsa, and D. J. Shepherd [Proceedings of the Royal Society A: Mathematical, Physical and Engineering Science 465, 1413 (2009).] and crucially strengthen its statement by taking noise effect into account. Classical simulatability below the boundary is shown by taking a projected-entangled-pair-state picture. Not only the separability criteria but also the condition for the entangled pair to become a convex mixture of stabilizer states is developed to show classical simulatability of highly entangling operations. We found that when each qubit is subject to a single-qubit complete-positive-trace-preserving noise, the computational quantum-classical boundary is tightly given by the dephasing rate required for the magic state distillation.

Keisuke Fujii; Shuhei Tamate

2014-06-26

338

Brain as quantum-like computer

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).

Andrei Khrennikov

2005-03-24

339

The Role of Grid Computing Technologies in Cloud Computing

\\u000a The fields of Grid, Utility and Cloud Computing have a set of common objectives in harnessing shared resources to optimally\\u000a meet a great variety of demands cost-effectively and in a timely manner Since Grid Computing started its technological journey\\u000a about a decade earlier than Cloud Computing, the Cloud can benefit from the technologies and experience of the Grid in building

David Villegas; Ivan Rodero; Liana Fong; Norman Bobroff; Yanbin Liu; Manish Parashar; S. Masoud Sadjadi

2010-01-01

340

Adiabatic quantum computing with spin qubits hosted by molecules.

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

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

2015-01-28

341

Campus Computer Store Information Technology Services

Campus Computer Store Information Technology Services 20 Place Riel, 1 Campus Drive 966-8375 ccs Computer Store is administering a license for SAS. It is licensed on a yearly pro-rated basis as outlined: _____________________________________________________ Student Number (if applicable): _______________________________________________ Location of Computer

Saskatchewan, University of

342

Assistive Technology for the Disabled Computer User.

ERIC Educational Resources Information Center

Assistive technology that can help disabled computer users is described, and a resource guide to computer help for the disabled is presented. The Americans with Disabilities Act of 1990 has broad implications for higher education, in that it mandates that colleges and universities give disabled students equal access to computers on public…

Wilson, Linda

343

Adaptive Computing Technology and the Disabled.

ERIC Educational Resources Information Center

Adaptive technology offers people with disabilities the opportunity not just to use computers, but to use computers to complete tasks that were previously not possible for them. Computers can be used to assist individuals with speech or writing impairments, physical or mobility impairments, visual impairments, and learning disabilities. (Author/JL)

Harrell, William L.

1998-01-01

344

Computer Technology Resources for Literacy Projects.

ERIC Educational Resources Information Center

This resource booklet was prepared to assist literacy projects and community adult education programs in determining the technology they need to serve more older persons. Section 1 contains the following reprinted articles: "The Human Touch in the Computer Age: Seniors Learn Computer Skills from Schoolkids" (Suzanne Kashuba); "Computer Instruction…

Florida State Council on Aging, Tallahassee.

345

Towards universal quantum computation through relativistic motion

We show how to use relativistic motion to generate continuous variable Gaussian cluster states within cavity modes. Our results can be demonstrated experimentally using superconducting circuits where tunable boundary conditions correspond to mirrors moving with velocities close to the speed of light. In particular, we propose the generation of a quadripartite square cluster state as a first example that can be readily implemented in the laboratory. Since cluster states are universal resources for universal one-way quantum computation, our results pave the way for relativistic quantum computation schemes.

Bruschi, David Edward; Kok, Pieter; Johansson, Göran; Delsing, Per; Fuentes, Ivette

2013-01-01

346

Random Numbers and Quantum Computers

ERIC Educational Resources Information Center

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…

McCartney, Mark; Glass, David

2002-01-01

347

From Cbits to Qbits: Teaching computer scientists quantum mechanics

NSDL National Science Digital Library

In this article, 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.

Mermin, N. D.

2004-04-29

348

Computing, Information and Communications Technology (CICT) Website

NASA Technical Reports Server (NTRS)

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).

Hardman, John; Tu, Eugene (Technical Monitor)

2002-01-01

349

Theory of measurement-based quantum computing

In the study of quantum computation, data is represented in terms of linear operators which form a generalized model of probability, and computations are most commonly described as products of unitary transformations, which are the transformations which preserve the quality of the data in a precise sense. This naturally leads to "unitary circuit models", which are models of computation in which unitary operators are expressed as a product of "elementary" unitary transformations. However, unitary transformations can also be effected as a composition of operations which are not all unitary themselves: the "one-way measurement model" is one such model of quantum computation. In this thesis, we examine the relationship between representations of unitary operators and decompositions of those operators in the one-way measurement model. In particular, we consider different circumstances under which a procedure in the one-way measurement model can be described as simulating a unitary circuit, by considering the combi...

de Beaudrap, Jonathan Robert Niel

2008-01-01

350

different potential hardware implemen- tations, quantum computer architecture is a rich field with an opTailoring Quantum Architectures to Implementation Style: A Quantum Computer for Mobile University {echi,lyon,mrm}@princeton.edu ABSTRACT In recent years, quantum computing (QC) research has moved

Martonosi, Margaret

351

Suppression of quantum chaos in a quantum computer hardware J. Lages* and D. L. Shepelyansky

Suppression of quantum chaos in a quantum computer hardware J. Lages* and D. L. Shepelyansky regimes in the quantum computer hardware are identified as a function of magnetic field gradient chaos and melting of quantum computer hardware 15Â17 . It has been also shown 18,19 that these static

Shepelyansky, Dima

352

The Role of Grid Computing Technologies in Cloud Computing

NASA Astrophysics Data System (ADS)

The fields of Grid, Utility and Cloud Computing have a set of common objectives in harnessing shared resources to optimally meet a great variety of demands cost-effectively and in a timely manner Since Grid Computing started its technological journey about a decade earlier than Cloud Computing, the Cloud can benefit from the technologies and experience of the Grid in building an infrastructure for distributed computing. Our comparison of Grid and Cloud starts with their basic characteristics and interaction models with clients, resource consumers and providers. Then the similarities and differences in architectural layers and key usage patterns are examined. This is followed by an in depth look at the technologies and best practices that have applicability from Grid to Cloud computing, including scheduling, service orientation, security, data management, monitoring, interoperability, simulation and autonomic support. Finally, we offer insights on how these techniques will help solve the current challenges faced by Cloud computing.

Villegas, David; Rodero, Ivan; Fong, Liana; Bobroff, Norman; Liu, Yanbin; Parashar, Manish; Sadjadi, S. Masoud

353

Simulating quantum computation by contracting tensor networks

The treewidth of a graph is a useful combinatorial measure of how close the graph is to a tree. We prove that a quantum circuit with T gates whose underlying graph has treewidth d can be simulated classically in poly(T)*exp(O(d)) time, which, in particular, is polynomial in T if d = O(logT). Among many implications, we show efficient simulations for quantum formulas, defined and studied by Yao (Proceedings of the 34th Annual Symposium on Foundations of Computer Science, 352-361, 1993), and for log-depth circuits whose gates apply to nearby qubits only, a natural constraint satisfied by most physical implementations. We also extend the result to show that one-way quantum computation of Raussendorf and Briegel (Physical Review Letters, 86:5188-5191, 2001), a universal quantum computation scheme very promising for its physical implementation, can be efficiently simulated by a randomized algorithm if its quantum resource is derived from a small-treewidth graph.

Markov, I; Markov, Igor; Shi, Yaoyun

2005-01-01

354

Feedback-controlled adiabatic quantum computation

NASA Astrophysics Data System (ADS)

We propose a simple feedback-control scheme for adiabatic quantum computation with superconducting flux qubits. The proposed method makes use of existing on-chip hardware to monitor the ground-state curvature, which is then used to control the computation speed to maximize the success probability. We show that this scheme can provide a polynomial speed-up in performance and that it is possible to choose a suitable set of feedback-control parameters for an arbitrary problem Hamiltonian.

Wilson, R. D.; Zagoskin, A. M.; Savel'ev, S.; Everitt, M. J.; Nori, Franco

2012-11-01

355

Fundamentals of universality in one-way quantum computation

In this paper, we build a framework allowing for a systematic investigation of the fundamental issue: ‘Which quantum states serve as universal resources for measurement-based (one-way) quantum computation?’ We start our study by re-examining what is exactly meant by ‘universality’ in quantum computation, and what the implications are for universal one-way quantum computation. Given the framework of a measurement-based quantum

M. Van den Nest; W. Dur; A. Miyake; H. J. Briegel

2007-01-01

356

(CICT) Computing, Information, and Communications Technology Overview

NASA Technical Reports Server (NTRS)

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.

VanDalsem, William R.

2003-01-01

357

Information Nano-Technologies: Transition from Classical to Quantum

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.

Alexander Yu. Vlasov

2009-12-04

358

Measurement-based quantum computation with cluster states

We give a detailed account of the one-way quantum computer, a scheme of quantum computation that consists entirely of one-qubit measurements on a particular class of entangled states, the cluster states. We prove its universality, describe why its underlying computational model is different from the network model of quantum computation and relate quantum algorithms to mathematical graphs. Further we investigate the scaling of required resources and give a number of examples for circuits of practical interest such as the circuit for quantum Fourier transformation and for the quantum adder. Finally, we describe computation with clusters of finite size.

Raussendorf, R

2003-01-01

359

Measurement-based quantum computation on cluster states

NASA Astrophysics Data System (ADS)

We give a detailed account of the one-way quantum computer, a scheme of quantum computation that consists entirely of one-qubit measurements on a particular class of entangled states, the cluster states. We prove its universality, describe why its underlying computational model is different from the network model of quantum computation, and relate quantum algorithms to mathematical graphs. Further we investigate the scaling of required resources and give a number of examples for circuits of practical interest such as the circuit for quantum Fourier transformation and for the quantum adder. Finally, we describe computation with clusters of finite size.

Raussendorf, Robert; Browne, Daniel E.; Briegel, Hans J.

2003-08-01

360

Tsunami Technologies: Online Cluster Computing

NSDL National Science Digital Library

TTI provides a unique cluster computing service accessible online from anywhere. TTI is committed to providing up-to-date, industry recognized, high performance computing (HPC) systems and services to companies and academia with the absolute best in customer service and support. And, because it is affordable, our services are even within reach of the individual scientist.

361

Quantum advantage for distributed computing without communication

Understanding the role that quantum entanglement plays as a resource in various information processing tasks is one of the crucial goals of quantum information theory. Here we propose a new perspective for studying quantum entanglement: distributed computation of functions without communication between nodes. To formalize this approach, we propose identity games. Surprisingly, despite of no-signaling, we obtain that non-local quantum strategies beat classical ones in terms of winning probability for identity games originating from certain bipartite and multipartite functions. Moreover we show that, for majority of functions, access to general non-signaling resources boosts success probability two times in comparison to classical ones, for number of outputs large enough.

L. Czekaj; M. Pawlowski; T. Vertesi; A. Grudka; M. Horodecki; R. Horodecki

2014-08-05

362

Ion Trap Quantum Computers: Performance Limits and Experimental Progress

In a quantum computer information would be represented by the quantum mechanical states of suitable atomic-scale systems. (A single bit of information represented by a two-level quantum system is known as a qubit.) This notion leads to the possibility of computing with quantum mechanical superpositions of numbers (\\

Richard Hughes

1998-01-01

363

Scheduling error correction operations for a quantum computer

In a (future) quantum computer a single logical quantum bit (qubit) will be made of multiple physical qubits. These extra physical qubits implement mandatory extensive error checking. The efficiency of error correction will fundamentally influence the performance of a future quantum computer, both in latency\\/speed and in error threshold (the worst error tolerated for an individual gate). Executing this quantum

Andrew J. Landahl; Robert D. Carr; Cynthia Ann Phillips; Anand Ganti

2010-01-01

364

Can quantum computing solve classically unsolvable problems?

T. D. Kieu has claimed that a quantum computing procedure can solve a classically unsolvable problem. Recent work of W. D. Smith has shown that Kieu's central mathematical claim cannot be sustained. Here, a more general critique is given of Kieu's proposal and some suggestions are made regarding the Church-Turing thesis.

Andrew Hodges

2005-12-29

365

Barium Ions for Quantum Computation Matthew Dietrich

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

Blinov, Boris

366

Accuracy threshold for postselected quantum computation

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

Panos Aliferis; Daniel Gottesman; John Preskill

2007-01-01

367

Active agents, intelligence and quantum computing

This paper reviews evidence from neuroscience and quantum computing theory in support of the notion of autonomy in the workings of cognitive processes. Deficits in speech, vision, and motor abilities are described to show how cognitive behavior is not based just on incoming sensory data. Active agents, to which the conscious mind may not have access, are described. Recent developments

Subhash C. Kak

2000-01-01

368

Industrial Superconducting Quantum Computer Development in Canada

Quantum computation is one of the most active areas of research in academia. Nearly every university in the world that has a science department has researchers who are working on either trying to build hardware or develop algorithms for these machines. In this talk I will describe D-Wave's goals and achievements in assembling a global research network, centered in Canada,

Geordie Rose

2002-01-01

369

A simulator for quantum computer hardware

We present new examples of the use of the quantum computer (QC) emulator. For educational purposes we describe the implementation of the CNOT and Toffoli gate, two basic building blocks of a QC, on a three qubit NMR-like QC.

Kristel Michielsen; Hans DeRaedt; Koen DeRaedt

2002-01-01

370

Quantum computation with Turaev-Viro codes

For a 3-manifold with triangulated boundary, the Turaev-Viro topological invariant can be interpreted as a quantum error-correcting code. The code has local stabilizers, identified by Levin and Wen, on a qudit lattice. Kitaev's toric code arises as a special case. The toric code corresponds to an abelian anyon model, and therefore requires out-of-code operations to obtain universal quantum computation. In contrast, for many categories, such as the Fibonacci category, the Turaev-Viro code realizes a non-abelian anyon model. A universal set of fault-tolerant operations can be implemented by deforming the code with local gates, in order to implement anyon braiding. We identify the anyons in the code space, and present schemes for initialization, computation and measurement. This provides a family of constructions for fault-tolerant quantum computation that are closely related to topological quantum computation, but for which the fault tolerance is implemented in software rather than coming from a physical medium.

Koenig, Robert, E-mail: rkoenig@caltech.ed [Institute for Quantum Information, California Institute of Technology, Pasadena, CA 91125 (United States); Kuperberg, Greg [Department of Mathematics, University of California, Davis, CA 95616 (United States); Reichardt, Ben W. [School of Computer Science, Institute for Quantum Computing, University of Waterloo, Waterloo, ON, N2L 3G1 (Canada)

2010-12-15

371

Blind Quantum Computing with Weak Coherent Pulses

NASA Astrophysics Data System (ADS)

The universal blind quantum computation (UBQC) protocol [A. Broadbent, J. Fitzsimons, and E. Kashefi, in Proceedings of the 50th Annual IEEE Symposiumon Foundations of Computer Science (IEEE Computer Society, Los Alamitos, CA, USA, 2009), pp. 517-526.] allows a client to perform quantum computation on a remote server. In an ideal setting, perfect privacy is guaranteed if the client is capable of producing specific, randomly chosen single qubit states. While from a theoretical point of view, this may constitute the lowest possible quantum requirement, from a pragmatic point of view, generation of such states to be sent along long distances can never be achieved perfectly. We introduce the concept of ? blindness for UBQC, in analogy to the concept of ? security developed for other cryptographic protocols, allowing us to characterize the robustness and security properties of the protocol under possible imperfections. We also present a remote blind single qubit preparation protocol with weak coherent pulses for the client to prepare, in a delegated fashion, quantum states arbitrarily close to perfect random single qubit states. This allows us to efficiently achieve ?-blind UBQC for any ?>0, even if the channel between the client and the server is arbitrarily lossy.

Dunjko, Vedran; Kashefi, Elham; Leverrier, Anthony

2012-05-01

372

Blind quantum computing with weak coherent pulses.

The universal blind quantum computation (UBQC) protocol [A. Broadbent, J. Fitzsimons, and E. Kashefi, in Proceedings of the 50th Annual IEEE Symposiumon Foundations of Computer Science (IEEE Computer Society, Los Alamitos, CA, USA, 2009), pp. 517-526.] allows a client to perform quantum computation on a remote server. In an ideal setting, perfect privacy is guaranteed if the client is capable of producing specific, randomly chosen single qubit states. While from a theoretical point of view, this may constitute the lowest possible quantum requirement, from a pragmatic point of view, generation of such states to be sent along long distances can never be achieved perfectly. We introduce the concept of ? blindness for UBQC, in analogy to the concept of ? security developed for other cryptographic protocols, allowing us to characterize the robustness and security properties of the protocol under possible imperfections. We also present a remote blind single qubit preparation protocol with weak coherent pulses for the client to prepare, in a delegated fashion, quantum states arbitrarily close to perfect random single qubit states. This allows us to efficiently achieve ?-blind UBQC for any ?>0, even if the channel between the client and the server is arbitrarily lossy. PMID:23003133

Dunjko, Vedran; Kashefi, Elham; Leverrier, Anthony

2012-05-18

373

Towards fault tolerant adiabatic quantum computation.

I show how to protect adiabatic quantum computation (AQC) against decoherence and certain control errors, using a hybrid methodology involving dynamical decoupling, subsystem and stabilizer codes, and energy gaps. Corresponding error bounds are derived. As an example, I show how to perform decoherence-protected AQC against local noise using at most two-body interactions. PMID:18518178

Lidar, Daniel A

2008-04-25

374

Error correction for a spin quantum computer

The problems of error correction in a spin quantum computer are discussed. For digital processing in the Ising and Heisenberg chains driven by a resonant electromagnetic field, the simple schemes are suggested which provide correction of errors caused by imperfect pi pulses, and prevent the most significant errors caused by the nonresonant action of pi pulses. The probability of error

Gennady P. Berman; David K. Campbell; Vladimir I. Tsifrinovich

1997-01-01

375

Quantum pathology of static internal imperfections in flawed quantum computers

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.

Murat Cetinbas; Joshua Wilkie

2007-05-28

376

Beyond Computation: Information Technology, Organizational

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

377

Overcoming efficiency constraints on blind quantum computation

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 constraints only hold in limited scenarios and show how to overcome it using a method based on iterated gate-teleportations. We present our results as a family of protocols, with varying degrees of computational-ability requirements on the client. Certain protocols in this family exponentially outperform previously known schemes in terms of total communication. The approach presented here can be adapted to other distributed computing protocols to reduce communication requirements.

Carlos A. Pérez-Delgado; Joseph F. Fitzsimons

2014-11-18

378

The General Quantum Interference Principle and the Duality Computer

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

Gui Lu Long

2006-05-10

379

Ultimate computing. Biomolecular consciousness and nano Technology

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.

Hameroff, S.R.

1987-01-01

380

Cost analysis of hash collisions: Will quantum computers

attacker--an attacker equipped with a large quantum computer? The power of today's cryptanalytic hardware]. Simulating this quantum computer on traditional hardware would make it exponentially slower. The goalCost analysis of hash collisions: Will quantum computers make SHARCS obsolete? Daniel J. Bernstein

Bernstein, Daniel

381

Simulation of Quantum Computers H. De Raedt1

to study the functioning of Quantum Computer hardware. The latter is modeled by a collection of interactingSimulation of Quantum Computers H. De Raedt1 , K. Michielsen2 , A.H. Hams1 , S. Miyashita3 , and K out by the Quantum Computer. Our simulation software consists of code that solves the time

382

Doc. Math.J. DMV 467 Quantum Computing

, given only moderately reliable quantum computing hardware. 1991 Mathematics Subject Classi cationDoc. Math.J. DMV 467 Quantum Computing Peter W. Shor Abstract. The Church-Turing thesis says that it entails at most a poly- nomial increase in computation time. This may not be true if quantum mechanics

Chinburg, Ted

383

A silicon-based nuclear spin quantum computer

Quantum computers promise to exceed the computational efficiency of ordinary classical machines because quantum algorithms allow the execution of certain tasks in fewer steps. But practical implementation of these machines poses a formidable challenge. Here I present a scheme for implementing a quantum-mechanical computer. Information is encoded onto the nuclear spins of donor atoms in doped silicon electronic devices. Logical

B. E. Kane

1998-01-01

384

Lower bounds for Quantum Computation and Communication Ashwin V. Nayak

Lower bounds for Quantum Computation and Communication by Ashwin V. Nayak B.Tech. (Indian Institute of California, Berkeley Fall 1999 #12;Lower bounds for Quantum Computation and Communication Copyright c 1999 by Ashwin V. Nayak #12;1 Abstract Lower bounds for Quantum Computation and Communication by Ashwin V. Nayak

Nayak, Ashwin

385

Measurement-Based Quantum Computation Robert B. Griffiths

and H. J. Briegel, "One-way Quantum Computation," arXiv:quant-ph/0603226 M. A. Nielsen, "Cluster. Raussendorf and H. J. Briegel, "A one-way quantum computer," Phys. Rev. Lett. 86 (2001) 5188 (The original Introduction The "circuit" scheme of quantum computation employs a number of qubits which are initially

Griffiths, Robert B.

386

Ancilla-driven universal quantum computing Vlad Gheorghiu

-state model. Introduced by R. Raussendorf and H.J Briegel, A one-way quantum computer. Phys. Rev. Lett. 86 There are 2 well-known universal models of quantum computation. The circuit model: decompose the U usingAncilla-driven universal quantum computing Vlad Gheorghiu Department of Physics Carnegie Mellon

Griffiths, Robert B.

387

Measurement-Based Quantum Computation Robert B. Griffiths

Xiv:quant-ph/0404132. D. E. Browne and H. J. Briegel, "One-way Quantum Computation," arXiv:quant-ph/0603226 M. AXiv:quant-ph/0504097v2 R. Raussendorf and H. J. Briegel, "A one-way quantum computer," Phys. Rev. Lett. 86 (2001) 5188 Introduction The "circuit" scheme of quantum computation employs a number of qubits which are initially

Griffiths, Robert B.

388

Holonomic quantum computation with electron spins in quantum dots

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.

Golovach, Vitaly N. [Arnold Sommerfeld Center for Theoretical Physics and Center for Nanoscience Department of Physics, Ludwig-Maximilians-Universitaet, Theresienstrasse 37, D-80333 Munich (Germany); Borhani, Massoud [Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland); Department of Physics, University at Buffalo, SUNY, Buffalo, New York 14260-1500 (United States); Loss, Daniel [Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland)

2010-02-15

389

Computer Maintenance Technology. Suggested Basic Course Outline.

ERIC Educational Resources Information Center

This competency-based basic course outline is designed for a two-year secondary program in computer maintenance technology. The first year is devoted to basic electricity and electronics, the second to the troubleshooting, maintenance, and service of microcomputers. (The repair section is based upon the Apple II computer, disc drive, monitor, and…

Texas A and M Univ., College Station. Vocational Instructional Services.

390

Computer-Optimized Adaptive Suspension Technology (COAST)

This paper presents a fundamental vehicle suspension system using real-time computer control. This Computer-Optimized Adaptive Suspension Technology (COAST) consists of a microprocessor-controlled, fully integrated, adaptive suspension system. COAST is capable of providing near-optimum performance for any land surface vehicle in any environment and can be implemented in a relatively simple and cost-effective manner.

James M. Hamilton

1985-01-01

391

Computer technology forecast study for general aviation

NASA Technical Reports Server (NTRS)

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.

Seacord, C. L.; Vaughn, D.

1976-01-01

392

Accuracy threshold for postselected quantum computation

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.

Panos Aliferis; Daniel Gottesman; John Preskill

2007-09-17

393

Adiabatic cluster-state quantum computing

NASA Astrophysics Data System (ADS)

Models of quantum computation (QC) are important because they change the physical requirements for achieving universal QC. For example, one-way QC requires the preparation of an entangled “cluster” state, followed by adaptive measurement on this state, a set of requirements which is different from the standard quantum-circuit model. Here we introduce a model based on one-way QC but without measurements (except for the final readout), instead using adiabatic deformation of a Hamiltonian whose initial ground state is the cluster state. Our results could help increase the feasibility of adiabatic schemes by using tools from one-way QC.

Bacon, Dave; Flammia, Steven T.

2010-09-01

394

Efficient Quantum Circuits for One-Way Quantum Computing

While Ising-type interactions are ideal for implementing controlled phase flip gates in one-way quantum computing, natural interactions between solid-state qubits are most often described by either the XY or the Heisenberg models. We show an efficient way of generating cluster states directly using either the imaginary SWAP (iSWAP) gate for the XY model, or the SWAP gate for the Heisenberg

Tetsufumi Tanamoto; Yu-Xi Liu; Xuedong Hu; Franco Nori

2009-01-01

395

Faculty of Computer Science & Technology

such as the provision of an optimal digital infrastructure; sensing the planet and optimising use of physical resources software, animation and gaming, as well as many of the major names in finance, defence, communications-known process theories and the extraordinary challenge that Ubiquitous Computing presents for sound engineering

Haddadi, Hamed

396

Non-unitary probabilistic quantum computing circuit and method

NASA Technical Reports Server (NTRS)

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.

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

2009-01-01

397

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

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 towards a negative answer. The first is a conjecture about physical realizations of quantum codes

Kalai, Gil

398

Information Technology Student: Computer Programming & Support

NSDL National Science Digital Library

In this video adapted from Pathways to Technology, learn how exploring an interest in computers can lead to a new career. After taking, and enjoying, an online course, Hilda Villavicencio decided to study computer programming and information technology (IT) at community college. Students who attend an IT program learn how computers function, so that whether they go into networking, technical support, or any other branch of IT, they bring a solid understanding of computer systems and how to maintain them. Hilda interns at the computer help-desk at her school where she uses what she's learning in the classroom to help others. She explains where she'd like to be in five years, and how her degree will take her there.The video runs 3:12 and is accompanied by a background essay, standards alignment, and discussion questions. Users who sign up for a free account can save the resource and download the video as well.

2012-05-30

399

Geometry, optimal control and quantum computing

NASA Astrophysics Data System (ADS)

Quantum computation promises solution to problems that are hard to solve by classical computers. The efficient construction of quantum circuits that can solve interesting tasks is a fundamental challenge in the field. Such efficient construction also reduces decoherence losses in physical implementations of quantum algorithms by reducing interaction time with the environment. Therefore, finding time-optimal ways to synthesize unitary transformations from available physical resources is a problem of both fundamental and practical interest in quantum information processing. In this thesis, we study these problems in general mathematical frame as well as in some concrete real physical settings. We give a complete characterization of all the unitary transformations that can be synthesized in a given time for a two-qubit system in presence of general time varying coupling tensor, assuming that the local unitary transformation on two qubits can be performed arbitrarily fast (on a time scale governed by the strength of couplings). A generalization of this result on general Lie group is also presented. We then give the time optimal ways for coherence transfer on three linearly coupled spin chain, and an efficient way of constructing a CNOT gate between two indirectly coupled spins.

Yuan, Haidong

400

Research on Key Technologies of Cloud Computing

NASA Astrophysics Data System (ADS)

With the development of multi-core processors, virtualization, distributed storage, broadband Internet and automatic management, a new type of computing mode named cloud computing is produced. It distributes computation task on the resource pool which consists of massive computers, so the application systems can obtain the computing power, the storage space and software service according to its demand. It can concentrate all the computing resources and manage them automatically by the software without intervene. This makes application offers not to annoy for tedious details and more absorbed in his business. It will be advantageous to innovation and reduce cost. It's the ultimate goal of cloud computing to provide calculation, services and applications as a public facility for the public, So that people can use the computer resources just like using water, electricity, gas and telephone. Currently, the understanding of cloud computing is developing and changing constantly, cloud computing still has no unanimous definition. This paper describes three main service forms of cloud computing: SAAS, PAAS, IAAS, compared the definition of cloud computing which is given by Google, Amazon, IBM and other companies, summarized the basic characteristics of cloud computing, and emphasized on the key technologies such as data storage, data management, virtualization and programming model.

Zhang, Shufen; Yan, Hongcan; Chen, Xuebin

401

Quantum computing with continuous-variable clusters

NASA Astrophysics Data System (ADS)

Continuous-variable cluster states offer a potentially promising method of implementing a quantum computer. This paper extends and further refines theoretical foundations and protocols for experimental implementation. We give a cluster-state implementation of the cubic phase gate through photon detection, which, together with homodyne detection, facilitates universal quantum computation. In addition, we characterize the offline squeezed resources required to generate an arbitrary graph state through passive linear optics. Most significantly, we prove that there are universal states for which the offline squeezing per mode does not increase with the size of the cluster. Simple representations of continuous-variable graph states are introduced to analyze graph state transformations under measurement and the existence of universal continuous-variable resource states.

Gu, Mile; Weedbrook, Christian; Menicucci, Nicolas C.; Ralph, Timothy C.; van Loock, Peter

2009-06-01

402

Electronic transient processes and optical spectra in quantum dots for quantum computing

Quantum dot systems are studied theoretically from the point of view of realization of quantum bit using the orbital state of electronic motion in a quantum dot. Attention is paid to several effects which can influence significantly the application of quantum dot electronic orbital states in quantum computing, for example, the effect of upconversion of the population and the incomplete

Karel Král; P. Zdenek; Z. Khas

2004-01-01

403

From reversible computation to quantum computation by Lagrange interpolation

Classical reversible circuits, acting on $w$~bits, are represented by permutation matrices of size $2^w \\times 2^w$. Those matrices form the group P($2^w$), isomorphic to the symmetric group {\\bf S}$_{2^w}$. The permutation group P($n$), isomorphic to {\\bf S}$_n$, contains cycles with length~$p$, ranging from~1 to $L(n)$, where $L(n)$ is the so-called Landau function. By Lagrange interpolation between the $p$~matrices of the cycle, we step from a finite cyclic group of order~$p$ to a 1-dimensional Lie group, subgroup of the unitary group U($n$). As U($2^w$) is the group of all possible quantum circuits, acting on $w$~qubits, such interpolation is a natural way to step from classical computation to quantum computation.

Alexis De Vos; Stijn De Baerdemacker

2015-02-03

404

Quantum computing with superconducting phase qubits

The superconducting phase qubit combines Josephson junctions into superconducting loops and defines one of the promising solid state device implementations for quantum computing. Here, we propose two hardware realizations for superconducting phase qubits, where the first is based on 2?-periodic s-wave–d-wave–s-wave Josephson junctions, while the second proposal involves five Josephson junctions arranged in a loop which is frustrated by a

G. Blatter; V. B. Geshkenbein; A. L. Fauchère; M. V. Feigel'man; L. B. Ioffe

2001-01-01

405

Quantum computing with superconducting phase qubits

The superconducting phase qubit combines Josephson junctions into superconducting loops and defines one of the promising solid state device implementations for quantum computing. Here, we propose two hardware realizations for superconducting phase qubits, where the first is based on \\/2phi-periodic s-wave-d-wave-s-wave Josephson junctions, while the second proposal involves five Josephson junctions arranged in a loop which is frustrated by a

G. Blatter; V. B. Geshkenbein; A. L. Fauchère; M. V. Feigel'man; L. B. Ioffe

2001-01-01

406

Poly-Locality in Quantum Computing

. A polynomial depth quantum circuit affects, by definition, a poly-local unitary transformation of a tensor product state\\u000a space. It is a reasonable belief [Fe], [L], [FKW] that, at a fine scale, these are precisely the transformations which will be available from physics to solve computational\\u000a problems. The poly-locality of a discrete Fourier transform on cyclic groups is at

Michael H. Freedman; Michael H. Freedman

2002-01-01

407

Computer Game and Simulation Technology

NSDL National Science Digital Library

This video, created by ATETV and presented by WGBH, takes a look at the Computer Game and Simulation program at Wake Technical Community College. This video provides an overview of the diverse range of classes that the program offers, as well as how students can specialize their education within the field. This video also explains that by studying game development students can also find a career in simulation development in almost any industry. This video is helpful for anyone interested in the field of game design or graphic design. Educators will also find a background essay, discussion questions, and standards alignment for the material. Running time for the video is 2:54.

2010-12-17

408

Quantum computation: algorithms and implementation in quantum dot devices

NASA Astrophysics Data System (ADS)

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..

Gamble, John King

409

Scalable quantum computer architecture with coupled donor-quantum dot qubits

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.

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

2014-08-26

410

Quantum Computation and Shor's Factoring Algorithm Ronald de Wolf

that are based on quantum- mechanical principles. We give a brief introduction to the model of quantum and other proper- ties of computers based on quantum-mechanical principles. Its main objective is to nd is intended to be a brief and incomplete introduction to the model of quantum com- putation and Shor

de Wolf, Ronald

411

Evolution of quantum computer algorithms from reversible operators

An application of an evolutionary approach to hardware design is presented. A genetic algorithm was developed to discover good designs for quantum computer algorithms. The algorithms are expressed as quantum operator sequences applied in a circuit model. The circuits discovered are configurations of special purpose quantum computers. We have been exploring the evolution of algorithms as alternative configurations of hardware.

A. J. Surkan; A. Khuskivadze

2002-01-01

412

Quantum optical technologies for metrology, sensing and imaging

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.

Jonathan P. Dowling; Kaushik P. Seshadreesan

2014-12-24

413

Compact quantum circuits from one-way quantum computation

NASA Astrophysics Data System (ADS)

In this paper we address the problem of translating one-way quantum computation (1WQC) into the circuit model. We start by giving a straightforward circuit representation of any 1WQC, at the cost of introducing many ancilla wires. We then propose a set of simple circuit identities that explore the relationship between the entanglement resource and correction structure of a 1WQC, allowing one to obtain equivalent circuits acting on fewer qubits. We conclude with some examples and a discussion of open problems.

Dias da Silva, Raphael; Galvão, Ernesto F.

2013-07-01

414

NASA Astrophysics Data System (ADS)

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

Demming, Anna

2010-07-01

415

Lecture Script: Introduction to Computational Quantum Mechanics

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. 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.

Roman Schmied

2014-03-27

416

Quantum computation over the butterfly network

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.

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

2011-07-14

417

Trapped Ion Quantum Computer Research at Los Alamos

We briefly review the development and theory of an experiment to investigate quantum computation with trapped calcium ions. The ion trap, laser and ion requirements are determined, and the parameters required for simple quantum logic operations are described

D. F. V. James; M. S. Gulley; M. H. Holzscheiter; R. J. Hughes; P. G. Kwiat; S. K. Lamoreaux; C. G. Peterson; V. D. Sandberg; M. M. Schauer; C. M. Simmons; D. Tupa; P. Z. Wang; A. G. White

1998-07-24

418

A general-purpose pulse sequencer for quantum computing

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 ...

Pháº¡m, Paul Tân Tháº¿

2005-01-01

419

Minimal computational-space implementation of multiround quantum protocols

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.

Bisio, Alessandro; D'Ariano, Giacomo Mauro; Perinotti, Paolo; Chiribella, Giulio [QUIT group, Dipartimento di Fisica ''A. Volta'', and INFN Sezione di Pavia, via Bassi 6, IT-27100 Pavia (Italy); Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, Ontario N2L 2Y5 (Canada)

2011-02-15

420

Computational advantage from quantum-controlled ordering of gates.

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

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

2014-12-19

421

Computational Advantage from Quantum-Controlled Ordering of Gates

NASA Astrophysics Data System (ADS)

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 (n2) queries. Furthermore, we conjecture that solving this problem in a classical computer takes exponential time, which may be of independent interest.

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

2014-12-01

422

Measurement-based quantum computation with trapped ions.

Measurement-based quantum computation represents a powerful and flexible framework for quantum information processing, based on the notion of entangled quantum states as computational resources. The most prominent application is the one-way quantum computer, with the cluster state as its universal resource. Here we demonstrate the principles of measurement-based quantum computation using deterministically generated cluster states, in a system of trapped calcium ions. First we implement a universal set of operations for quantum computing. Second we demonstrate a family of measurement-based quantum error correction codes and show their improved performance as the code length is increased. The methods presented can be directly scaled up to generate graph states of several tens of qubits. PMID:24313469

Lanyon, B P; Jurcevic, P; Zwerger, M; Hempel, C; Martinez, E A; Dür, W; Briegel, H J; Blatt, R; Roos, C F

2013-11-22

423

Multiple RF Coil Nuclear Magnetic Resonance Quantum Computing

Recent work has demonstrated the feasibility of using an array of quantum information processors connected via classical channels\\u000a (type II quantum computer) to implement a quantum lattice-gas algorithm. This paper describes work towards constructing a\\u000a new experimental set-up for a type II quantum computer. This set-up has new hardware and software specifications but does\\u000a follow previously published approaches of operation

Lisa C. Siskind; Bruce E. Hammer; Nelson L. Christensen; Jeffrey Yepez

2005-01-01

424

New Approaches to Quantum Computing using Nuclear Magnetic Resonance Spectroscopy

The power of a quantum computer (QC) relies on the fundamental concept of the superposition in quantum mechanics and thus allowing an inherent large-scale parallelization of computation. In a QC, binary information embodied in a quantum system, such as spin degrees of freedom of a spin-1\\/2 particle forms the qubits (quantum mechanical bits), over which appropriate logical gates perform the

M Colvin; V V Krishnan

2003-01-01

425

Poly-locality in quantum computing

A polynomial depth quantum circuit effects, by definition a poly-local unitary transformation of tensor product state space. It is a physically reasonable belief [Fy][L][FKW] that these are precisely the transformations which will be available from physics to help us solve computational problems. The poly-locality of discrete Fourier transform on cyclic groups is at the heart of Shor's factoring algorithm. We describe a class of poly-local transformations, including all the discrete orthogonal wavelet transforms in the hope that these may be helpful in constructing new quantum algorithms. We also observe that even a rather mild violation of poly-locality leads to a model without one-way functions, giving further evidence that poly-locality is an essential concept.

Freedman, M H

2000-01-01

426

Beam damage detection using computer vision technology

In this paper, a new approach for efficient damage detection in engineering structures is introduced. The key concept is to use the mature computer vision technology to capture the static deformation profile of a structure, and then employ profile analysis methods to detect the locations of the damages. By combining with wireless communication techniques, the proposed approach can provide an

Jing Shi; Xiangjun Xu; Jialai Wang; Gong Li

2010-01-01

427

Oasis cooling packaging technology for notebook computers

It is imperative that designers, OEMs and systems integrators address system-wide thermal issues, and do it from the earliest stages of product design. As this technique is practised, engineers will be working with a broader array of technologies and disciplines than ever before. Consumer demand for powerful, portable computing products is the major driving force for new thermal techniques, An

G. Kuzmin

1994-01-01

428

Women Workers as Users of Computer Technology.

ERIC Educational Resources Information Center

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…

Larwood, Laurie

1992-01-01

429

FPGA-based high-speed emulator of quantum computing

Quantum computers are believed to perform high-speed calculations, compared with conventional computers. However, the quantum computer has inherent issues. Firstly, it solves NP (non-deterministic polynomial) problems at a high speed only when a periodic function can be used in the process of calculation. Secondly, it is extremely difficult to increase the problem scale to be solved, which is determined by

Minoru Fujishima

2003-01-01

430

Measurement-Based Quantum Computation Robert B. Griffiths

and H. J. Briegel, "One-way Quantum Computation," arXiv:quant-ph/0603226 M. A. Nielsen, "ClusterXiv:0901.3092v2 [quant-ph] 1 Introduction The "circuit" scheme of quantum computation employs a number" and "one-way computation") assumes a collection of qubits that are initially entangled with each other

Griffiths, Robert B.

431

I will discuss the revolutionary new concept of topological quantum computation, which is fault-tolerant at the hardware level with no need, in principle, of any quantum error correction protocols. Errors simply do not occur since the physical qubits and the computation steps are protected against decoherence by non-local topological correlations in the underlying physical system. The key idea is non-Abelian statistics of the quasiparticles (called 'anyons' as opposed to fermions or bosons), where the space-time braiding of the anyons around each other, i.e. quantum 'knots', form topologically protected quantum gate operations. I will describe in detail the theoretical principles guiding the experimental search for the appropriate topological phases of matter where such non-Abelian anyons, which are low-dimensional solid state versions of the elusive and exotic Majorana fermions hypothesized seventy-five years ago, may exist. I will critically discuss the recent experimental claims of observing the Majorana modes in semiconductor nanowire structures following earlier theoretical proposals, outlining the future developments which would be necessary to eventually build a topological quantum computer.

Das Sarma, Sankar [University of Maryland

2012-10-03

432

Implementing unitary operators in quantum computation

We present a general method which expresses a unitary operator by the product of operators allowed by the Hamiltonian of spin-1/2 systems. In this method, the generator of an operator is found first, and then the generator is expanded by the base operators of the product operator formalism. Finally, the base operators disallowed by the Hamiltonian, including more than two-body interaction operators, are replaced by allowed ones by the axes transformation and coupling order reduction technique. This method directly provides pulse sequences for the nuclear magnetic resonance quantum computer, and can be generally applied to other systems.

Jaehyun Kim; Jae-Seung Lee; Soonchil Lee

1999-08-16

433

Spacetime Foam, Holographic Principle, and Black Hole Quantum Computers

Spacetime foam, also known as quantum foam, has its origin in quantum fluctuations of spacetime. Arguably it is the source of the holographic principle, which severely limits how densely information can be packed in space. Its physics is also intimately linked to that of black holes and computation. In particular, the same underlying physics is shown to govern the computational power of black hole quantum computers.

Y. Jack Ng; H. van Dam

2004-03-13

434

Spacetime Foam, Holographic Principle, and Black Hole Quantum Computers

NASA Astrophysics Data System (ADS)

Spacetime foam, also known as quantum foam, has its origin in quantum fluctuations of spacetime. Arguably it is the source of the holographic principle, which severely limits how densely information can be packed in space. Its physics is also intimately linked to that of black holes and computation. In particular, the same underlying physics is shown to govern the computational power of black hole quantum computers.

Ng, Y. Jack; van Dam, H.

435

Spacetime Foam, Holographic Principle, and Black Hole Quantum Computers

NASA Astrophysics Data System (ADS)

Spacetime foam, also known as quantum foam, has its origin in quantum fluctuations of spacetime. Arguably it is the source of the holographic principle, which severely limits how densely information can be packed in space. Its physics is also intimately linked to that of black holes and computation. In particular, the same underlying physics is shown to govern the computational power of black hole quantum computers.

Ng, Y. Jack; van Dam, H.

2004-01-01

436

Universal Quantum Gates for Single Cooper Pair Box Based Quantum Computing

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. Quantum gate operations are achieved by applying sequences of voltages and magnetic fluxes to single qubits or pairs of qubits. Neither the temporal duration, nor

P. Echternachl; C. P. Williams; S. C. Dultzl; S. Braunstein

437

Universal Quantum Gates for Single Cooper Pair Box Based Quantum Computing

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. Quantum gate operations are achieved by applying sequences of voltages and magnetic fluxes to single qubits or pairs of qubits. Neither the temporal duration, nor

P. Echternach; C. P. Williams; S. C. Dultz; P. Delsing; S. L. Braunstein; J. P. Dowling

2001-01-01

438

Quantum Computation with Coherent States, Linear Interactions and Superposed Resources

We show that quantum computation circuits with coherent states as the logical qubits can be constructed using very simple linear networks, conditional measurements and coherent superposition resource states.

T. C. Ralph; W. J. Munro; G. J. Milburn

2001-10-18

439

Reviews of computing technology: Object-oriented technology

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.

Skeen, D.C.

1993-03-01

440

Surface code quantum computing by lattice surgery

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...

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

2011-01-01

441

Maximizing a transport platform through computer technology.

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

Hudson, Timothy L

2003-01-01

442

Quantum dot quantum computation in III-V type semiconductor

NASA Astrophysics Data System (ADS)

Among recent proposals for next-generation, non-charge-based logic is the notion that a single electron can be trapped and spin of the electron can be manipulated through the application of gate potentials. In the thesis, there are two major contributions of the manipulation of electron spin. In regard to the first contribution, we present numerical simulations of such a spin in single electron devices for realistic asymmetric potentials in electrostatically confined quantum dot. Using analytical and numerical techniques we show that breaking in-plane rotational symmetry of the confining potential by applied gate voltage leads to a significant effect on the tuning of the electron g-factor. In particular, we find that anisotropy extends the tunability to larger quantum dots in the GaAs case. Although the same extension of tunability exists in the InAs quantum dot case, we find a new effect in the InAs case. The new discovery is that broken in-plane rotational symmetry due to the Rashba spin-orbit coupling in an asymmetric potential results in a significant reverse effect in the tuning of the electron g-factor. This effect can not be observed in symmetric case. The derivative of the g-factor with respect to the electric field has the opposite sign in the above two potentials. The manipulation of Berry phases of spin in nano-scale devices is a topic that has received recent attention as a promising candidate for solid state quantum computation and non-charge-based logic devices. A single electron in an electrostatically defined quantum dot located in a 2 dimensional electron gas (2DEG), for example, can be trapped and the spin can be manipulated by simply moving the center of mass of the quantum dot adiabatically along a closed loop in the 2D plane via the application of gate potentials. In relation to the second contribution, we present numerical simulations and analytical expressions for the spin-dependent electron propagator (a matrix-valued function of position) for an electron trapped in a quantum dot, while the center of mass of the quantum dot is adiabatically moved in the 2D plane in the presence of the Rashba and Dresselhaus spin-orbit interactions. We apply the Feynman disentangling technique to determine the non-abelian matrix Berry phase, we find exact analytical expression for the propagator in three cases: (a) pure Rashba coupling; (b) pure Dresselhaus coupling; and (c) a combination of equally strong Rashba and Dresselhaus couplings. For other cases of interest where the solution of the propagator can not be found analytically, we present results obtained by numerically solving the Riccati equation resulting from the disentangling procedure. We also find that the presence of both spin-orbit couplings leads to a larger spin-flip probability than what would result from either mechanism considered separately.

Prabhakar, Sanjay Kumar

443

Algorithmic cooling and scalable NMR quantum computers

We present here algorithmic cooling (via polarization heat bath)—a powerful method for obtaining a large number of highly polarized spins in liquid nuclear-spin systems at finite temperature. Given that spin-half states represent (quantum) bits, algorithmic cooling cleans dirty bits beyond the Shannon's bound on data compression, by using a set of rapidly thermal-relaxing bits. Such auxiliary bits could be implemented by using spins that rapidly get into thermal equilibrium with the environment, e.g., electron spins. Interestingly, the interaction with the environment, usually a most undesired interaction, is used here to our benefit, allowing a cooling mechanism. Cooling spins to a very low temperature without cooling the environment could lead to a breakthrough in NMR experiments, and our “spin-refrigerating” method suggests that this is possible. The scaling of NMR ensemble computers is currently one of the main obstacles to building larger-scale quantum computing devices, and our spin-refrigerating method suggests that this problem can be resolved. PMID:11904402

Boykin, P. Oscar; Mor, Tal; Roychowdhury, Vwani; Vatan, Farrokh; Vrijen, Rutger

2002-01-01

444

Page Recognition: Quantum Leap In Recognition Technology

NASA Astrophysics Data System (ADS)

No milestone has proven as elusive as the always-approaching "year of the LAN," but the "year of the scanner" might claim the silver medal. Desktop scanners have been around almost as long as personal computers. And everyone thinks they are used for obvious desktop-publishing and business tasks like scanning business documents, magazine articles and other pages, and translating those words into files your computer understands. But, until now, the reality fell far short of the promise. Because it's true that scanners deliver an accurate image of the page to your computer, but the software to recognize this text has been woefully disappointing. Old optical-character recognition (OCR) software recognized such a limited range of pages as to be virtually useless to real users. (For example, one OCR vendor specified 12-point Courier font from an IBM Selectric typewriter: the same font in 10-point, or from a Diablo printer, was unrecognizable!) Computer dealers have told me the chasm between OCR expectations and reality is so broad and deep that nine out of ten prospects leave their stores in disgust when they learn the limitations. And this is a very important, very unfortunate gap. Because the promise of recognition -- what people want it to do -- carries with it tremendous improvements in our productivity and ability to get tons of written documents into our computers where we can do real work with it. The good news is that a revolutionary new development effort has led to the new technology of "page recognition," which actually does deliver the promise we've always wanted from OCR. I'm sure every reader appreciates the breakthrough represented by the laser printer and page-makeup software, a combination so powerful it created new reasons for buying a computer. A similar breakthrough is happening right now in page recognition: the Macintosh (and, I must admit, other personal computers) equipped with a moderately priced scanner and OmniPage software (from Caere Corporation) can recognize not only different fonts (omnifont recogniton) but different page (omnipage) formats, as well.

Miller, Larry

1989-07-01

445

Quantum tunneling, quantum computing, and high temperature superconductivity

NASA Astrophysics Data System (ADS)

In this dissertation, I have studied four theoretical problems in quantum tunneling, quantum computing, and high-temperature superconductivity. (1) I have developed a generally-useful numerical tool for analyzing impurity-induced resonant-state images observed with scanning tunneling microscope (STM) in high-Tc superconductors. The integrated tunneling intensities on all predominant sites have been estimated. The results can be used to test the predictions of any tight-binding model calculation. (2) I have numerically simulated two-dimensional time-dependent tunneling of a Gaussian wave packet through a barrier, which contains charged ions. We have found that a negative ion in the barrier directly below the tunneling tip can deflect the tunneling electrons and drastically reduce the probability for them to reach the point in the target plane directly below the tunneling tip. (3) I have studied an infinite family of sure-success quantum algorithms, which are introduced by C.-R. Hu [Phys. Rev. A 66, 042301 (2002)], for solving a generalized Grover search problem. Rigorous proofs are found for several conjectures made by Hu and explicit equations are obtained for finding the values of two phase parameters which make the algorithms sure success. (4) Using self-consistent Hartree-Fock theory, I have studied an extended Hubbard model which includes quasi-long-range Coulomb interaction between the holes (characterized by parameter V). I have found that for sufficiently large V/t, doubly-charged-antiphase-island do become energetically favored localized objects in this system for moderate values of U/t, thus supporting a recent conjecture by C.-R. Hu [Int. J. Mod. Phys. B 17, 3284 (2003)].

Wang, Qian

2003-10-01

446

A Computational Model for Observation in Quantum Mechanics

A computational model of observation in quantum mechanics is presented. The model provides a clean and simple computational paradigm which can be used to illustrate and possibly explain some of the unintuitive and ...

Rozas, Guillermo Juan

1987-03-01

447

Surface code quantum computing by lattice surgery

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.

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

2011-11-17

448

Quantum well photoconductors in infrared detector technology

NASA Astrophysics Data System (ADS)

The paper compares the achievements of quantum well infrared photodetector (QWIP) technology with those of competitive technologies, with the emphasis on the material properties, device structure, and their impact on focal plane array (FPA) performance. Special attention is paid to two competitive technologies, QWIP and HgCdTe, in the long-wavelength IR (LWIR) and very-long-wavelength IR (VLWIR) spectral ranges. Because so far, the dialogue between the QWIP and HgCdTe communities is limited, the paper attempts to settle the main issues of both technologies. Such an approach, however, requires the presentation of fundamental limits to the different types of detectors, which is made at the beginning. To write the paper more clearly for readers, many details are included in the Appendix. In comparative studies both photon and thermal detectors are considered. Emphasis is placed on photon detectors. In this group one may distinguish HgCdTe photodiodes, InSb photodiodes, and doped silicon detectors. The potential performance of different materials as infrared detectors is examined utilizing the ?/G ratio, where ? is the absorption coefficient and G is the thermal generation rate. It is demonstrated that LWIR QWIP's cannot compete with HgCdTe photodiodes as single devices, especially at higher operating temperatures (>70 K). This is due to the fundamental limitations associated with intersubband transitions. The advantage of HgCdTe is, however, less distinct at temperatures lower than 50 K due to problems inherent in the HgCdTe material (p-type doping, Shockley-Read recombination, trap-assisted tunneling, surface and interface instabilities). Even though QWIP is a photoconductor, several of its properties, such as high impedance, fast response time, long integration time, and low power consumption, comply well with the requirements imposed on the fabrication of large FPA's. Due to a high material quality at low temperatures, QWIP has potential advantages over HgCdTe in the area of VLWIR FPA applications in terms of array size, uniformity, yield, and cost of the systems. The performance figures of merit of state-of-the-art QWIP and HgCdTe FPA's are similar because the main limitations come from the readout circuits. Performance is, however, achieved with very different integration times. The choice of the best technology is therefore driven by the specific needs of a system. In the case of readout-limited detectors a low photoconductive gain increases the signal-to-noise ratio and a QWIP FPA can have a better noise equivalent difference temperature than an HgCdTe FPA with a charge well of similar size. Both HgCdTe photodiodes and QWIP's offer multicolor capability in the MWIR and LWIR range. Powerful possibilities offered by QWIP technology are associated with VLWIR FPA applications and with multicolor detection. The intrinsic advantage of QWIP's in this niche is due to the relative ease of growing multicolor structures with a very low defect density.

Rogalski, A.

2003-04-01

449

Grid computing technology for hydrological applications

NASA Astrophysics Data System (ADS)

SummaryAdvances in e-Infrastructure promise to revolutionize sensing systems and the way in which data are collected and assimilated, and complex water systems are simulated and visualized. According to the EU Infrastructure 2010 work-programme, data and compute infrastructures and their underlying technologies, either oriented to tackle scientific challenges or complex problem solving in engineering, are expected to converge together into the so-called knowledge infrastructures, leading to a more effective research, education and innovation in the next decade and beyond. Grid technology is recognized as a fundamental component of e-Infrastructures. Nevertheless, this emerging paradigm highlights several topics, including data management, algorithm optimization, security, performance (speed, throughput, bandwidth, etc.), and scientific cooperation and collaboration issues that require further examination to fully exploit it and to better inform future research policies. The paper illustrates the results of six different surface and subsurface hydrology applications that have been deployed on the Grid. All the applications aim to answer to strong requirements from the Civil Society at large, relatively to natural and anthropogenic risks. Grid technology has been successfully tested to improve flood prediction, groundwater resources management and Black Sea hydrological survey, by providing large computing resources. It is also shown that Grid technology facilitates e-cooperation among partners by means of services for authentication and authorization, seamless access to distributed data sources, data protection and access right, and standardization.

Lecca, G.; Petitdidier, M.; Hluchy, L.; Ivanovic, M.; Kussul, N.; Ray, N.; Thieron, V.

2011-06-01

450

Computational Support for Technology- Investment Decisions

NASA Technical Reports Server (NTRS)

Strategic Assessment of Risk and Technology (START) is a user-friendly computer program that assists human managers in making decisions regarding research-and-development investment portfolios in the presence of uncertainties and of non-technological constraints that include budgetary and time limits, restrictions related to infrastructure, and programmatic and institutional priorities. START facilitates quantitative analysis of technologies, capabilities, missions, scenarios and programs, and thereby enables the selection and scheduling of value-optimal development efforts. START incorporates features that, variously, perform or support a unique combination of functions, most of which are not systematically performed or supported by prior decision- support software. These functions include the following: Optimal portfolio selection using an expected-utility-based assessment of capabilities and technologies; Temporal investment recommendations; Distinctions between enhancing and enabling capabilities; Analysis of partial funding for enhancing capabilities; and Sensitivity and uncertainty analysis. START can run on almost any computing hardware, within Linux and related operating systems that include Mac OS X versions 10.3 and later, and can run in Windows under the Cygwin environment. START can be distributed in binary code form. START calls, as external libraries, several open-source software packages. Output is in Excel (.xls) file format.

Adumitroaie, Virgil; Hua, Hook; Lincoln, William; Block, Gary; Mrozinski, Joseph; Shelton, Kacie; Weisbin, Charles; Elfes, Alberto; Smith, Jeffrey

2007-01-01

451

The Study of Entangled States in Quantum Computation and Quantum Information Science

This thesis explores the use of entangled states in quantum computation and\\u000aquantum information science. Entanglement, a quantum phenomenon with no\\u000aclassical counterpart, has been identified as an important and quantifiable\\u000aresource in many areas of theoretical quantum information science, including\\u000aquantum error correction, quantum cryptography, and quantum algorithms. We\\u000afirst investigate the equivalence classes of a particular class of

Hyeyoun Chung

2008-01-01

452

Quantum optics: Cool computation, hot bits

NASA Astrophysics Data System (ADS)

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.

Lloyd, Seth

2014-02-01

453

Enhanced Fault-Tolerant Quantum Computing in d -Level Systems

NASA Astrophysics Data System (ADS)

Error-correcting codes protect quantum information and form the basis of fault-tolerant quantum computing. Leading proposals for fault-tolerant quantum computation require codes with an exceedingly rare property, a transversal non-Clifford gate. Codes with the desired property are presented for d -level qudit systems with prime d . The codes use n =d -1 qudits and can detect up to ˜d /3 errors. We quantify the performance of these codes for one approach to quantum computation known as magic-state distillation. Unlike prior work, we find performance is always enhanced by increasing d .

Campbell, Earl T.

2014-12-01

454

Twisted graph states for ancilla-driven quantum computation

We introduce a new paradigm for quantum computing called Ancilla-Driven Quantum Computation (ADQC) which combines aspects of the quantum circuit and the one-way model to overcome challenging issues in building large-scale quantum computers. Instead of directly manipulating each qubit to perform universal quantum logic gates or measurements, ADQC uses a fixed two-qubit interaction to couple the memory register of a quantum computer to an ancilla qubit. By measuring the ancilla, the measurement-induced back-action on the system performs the desired logical operations. The underlying mathematical model is based on a new entanglement resource called twisted graph states generated from non-commuting operators. The ADQC model is formalised in an algebraic framework similar to the Measurement Calculus. Furthermore, we present the notion of causal flow for twisted graph states, based on the stabiliser formalism, to characterise the determinism. Finally we demonstrate compositional embedding between ADQC and both the ...

Kashefi, Elham; Browne, Daniel E; Anders, Janet; Andersson, Erika

2009-01-01

455

The Brain Is both Neurocomputer and Quantum Computer

ERIC Educational Resources Information Center

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…

Hameroff, Stuart R.

2007-01-01

456

A Very Simple Example of Parallel Quantum Computation Frank Rioux

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

Rioux, Frank

457

Noisy Quantum Computation Thesis submitted for the degree

Noisy Quantum Computation Thesis submitted for the degree Doctor of Philosophy by Dorit Aharonov questions, shared their knowledge with me, and helped me in one way or another. Just a few of them and freedom that they gave me will be with me for life. #12; Contents I Quantum Computation- An Overview 3 II

Wiseman, Yair

458

One-way Quantum Computation - a tutorial introduction

In this book chapter, we provide a tutorial introduction to one-way quantum computation and many of the techniques one can use to understand it. The techniques which are described include the stabilizer formalism and the logical Heisenberg picture. We highlight ways in which it is useful to understand one-way computation beyond simple equivalence with the quantum circuit model. We briefly

Dan E. Browne; Hans J. Briegel

2006-01-01

459

Nano-Bio Quantum Technology for Device-Specific Materials

NASA Technical Reports Server (NTRS)

The areas discussed are still under development: I. Nano structured materials for TE applications a) SiGe and Be.Te; b) Nano particles and nanoshells. II. Quantum technology for optical devices: a) Quantum apertures; b) Smart optical materials; c) Micro spectrometer. III. Bio-template oriented materials: a) Bionanobattery; b) Bio-fuel cells; c) Energetic materials.

Choi, Sang H.

2009-01-01

460

Effective fault-tolerant quantum computation with slow measurements

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.

David P. DiVincenzo; Panos Aliferis

2006-08-03

461

Computational study of confined states in quantum dots by an efficient finite difference method.

??Semiconductor quantum dot systems have gained more attention in quantum computation and optoelectronic applications due to the ease of bandstructure tailoring and three-dimensional quantum confinement.… (more)

Butt, Salman

2010-01-01

462

Notes for Space-Efficient Quantum Computer Simulator Michael P. Frank (mpf@eng.fsu.edu)

................................................................................... 11 1. Text for Proposal Simulating quantum computers on ordinary classical digital hardware is usefulNotes for Space-Efficient Quantum Computer Simulator Michael P. Frank (mpf@eng.fsu.edu) Started) ................................................. 8 qconfig.txt (Quantum Computer Configuration

Frank, Michael P.

463

Noisy one-way quantum computations: The role of correlations

A scheme to evaluate computation fidelities within the one-way model is developed and explored to understand the role of correlations in the quality of noisy quantum computations. The formalism is promptly applied to many computation instances and unveils that a higher amount of entanglement in the noisy resource state does not necessarily imply a better computation.

Chaves, Rafael [ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona) (Spain); Instituto de Fisica, Universidade Federal do Rio de Janeiro, Rio de Janeiro (Brazil); Physikalisches Institut der Albert-Ludwigs-Universitaet, Freiburg (Germany); Melo, Fernando de [Instituut voor Theoretische Fysica, Katholieke Universiteit Leuven, Leuven (Belgium); Physikalisches Institut der Albert-Ludwigs-Universitaet, Freiburg (Germany)

2011-08-15

464

Magnetic qubits as hardware for quantum computers

We propose two potential realisations for quantum bits based on nanometre scale magnetic particles of large spin S and high anisotropy molecular clusters. In case (1) the bit-value basis states |0> and |1> are the ground and first excited spin states Sz = S and S-1, separated by an energy gap given by the ferromagnetic resonance (FMR) frequency. In case (2), when there is significant tunnelling through the anisotropy barrier, the qubit states correspond to the symmetric, |0>, and antisymmetric, |1>, combinations of the two-fold degenerate ground state Sz = +- S. In each case the temperature of operation must be low compared to the energy gap, \\Delta, between the states |0> and |1>. The gap \\Delta in case (2) can be controlled with an external magnetic field perpendicular to the easy axis of the molecular cluster. The states of different molecular clusters and magnetic particles may be entangled by connecting them by superconducting lines with Josephson switches, leading to the potential for quantum computing hardware.

J. Tejada; E. M. Chudnovsky; E. del Barco; J. M. Hernandez; T. P. Spiller

2000-09-28

465

Number Partitioning via Quantum Adiabatic Computation

NASA Technical Reports Server (NTRS)

We study both analytically and numerically the complexity of the adiabatic quantum evolution algorithm applied to random instances of combinatorial optimization problems. We use as an example the NP-complete set partition problem and obtain an asymptotic expression for the minimal gap separating the ground and exited states of a system during the execution of the algorithm. We show that for computationally hard problem instances the size of the minimal gap scales exponentially with the problem size. This result is in qualitative agreement with the direct numerical simulation of the algorithm for small instances of the set partition problem. We describe the statistical properties of the optimization problem that are responsible for the exponential behavior of the algorithm.

Smelyanskiy, Vadim N.; Toussaint, Udo; Clancy, Daniel (Technical Monitor)

2002-01-01

466

Parallel Photonic Quantum Computation Assisted by Quantum Dots in One-Side Optical Microcavities

Universal quantum logic gates are important elements for a quantum computer. In contrast to previous constructions on one degree of freedom (DOF) of quantum systems, we investigate the possibility of parallel quantum computations dependent on two DOFs of photon systems. We construct deterministic hyper-controlled-not (hyper-CNOT) gates operating on the spatial-mode and the polarization DOFs of two-photon or one-photon systems by exploring the giant optical circular birefringence induced by quantum-dot spins in one-sided optical microcavities. These hyper-CNOT gates show that the quantum states of two DOFs can be viewed as independent qubits without requiring auxiliary DOFs in theory. This result can reduce the quantum resources by half for quantum applications with large qubit systems, such as the quantum Shor algorithm. PMID:25030424

Luo, Ming-Xing; Wang, Xiaojun

2014-01-01

467

Technology and Computers in Music and Music Nicholas Reynolds

Technology and Computers in Music and Music Education Nicholas Reynolds Melbourne Graduate School in music education literature about what the technology is but little on what the technology means in terms at musical development in different ways. Computers and technology are viewed by Webster and Hickey [9

Paris-Sud XI, UniversitÃ© de

468

Quantum computing with semiconductor double-dot molecules on a chip

We develop a scalable architecture for quantum computation using controllable electrons of double-dot molecules coupled to a microwave stripline resonator on a chip, which satisfies all Divincenzo criteria. We analyze the performance and stability of all required operations and emphasize that all techniques are feasible with current experimental technologies.

Peng Xue

2010-01-18

469

A Brief History of Human Computer Interaction Technology

A Brief History of Human Computer Interaction Technology Brad A. Myers December, 1996 CMUÂCSÂ96Â163 CMUÂHCIIÂ96Â103 Human Computer Interaction Institute School of Computer Science Carnegie Mellon development of major advances in humanÂ computer interaction technology, emphasizing the pivotal role

Myers, Brad A.

470

The Intel Science and Technology Center for Cloud Computing

Intel Labs The Intel Science and Technology Center for Cloud Computing Foundations for Future Clouds Abstract The Intel Science and Technology Center for cloud computing (ISTC-CC) is an open, and productivity improvements in cloud computing. White Paper Intel Labs ISTC for Cloud Computing #12;The Intel

471

Computer Science and Technology Publications. NBS Publications List 84.

ERIC Educational Resources Information Center

This bibliography lists publications of the Institute for Computer Sciences and Technology of the National Bureau of Standards. Publications are listed by subject in the areas of computer security, computer networking, and automation technology. Sections list publications of: (1) current Federal Information Processing Standards; (2) computer…

National Bureau of Standards (DOC), Washington, DC. Inst. for Computer Sciences and Technology.

472

Photonic Implementation of Quantum Computation Algorithm Based on Spatial Coding

Several implementation methods of quantum computation algorithm by conventional computer have been explored for large-scale\\u000a emulation. Due to the lack of quantum effects, these methods generally require exponential growth of the size of the hardware\\u000a with increase of the number of qubits. In this paper, the spatial coding, which is an effective digital optical computing\\u000a technique, is studied as an

Naoya Tate; Yusuke Ogura; Jun Tanida

2007-01-01

473

A modular functor which is universal for quantum computation

We show that the topological modular functor from Witten-Chern-Simons theory is universal for quantum computation in the sense a quantum circuit computation can be efficiently approximated by an intertwining action of a braid on the functor's state space. A computational model based on Chern-Simons theory at a fifth root of unity is defined and shown to be polynomially equivalent to

Michael Freedman; Michael Larsen; Zhenghan Wang; Michael H. Freedman

2000-01-01

474

Method for implementation of universal quantum logic gates in a scalable Ising spin quantum computer

We present protocols for implementation of universal quantum gates on an arbitrary superposition of quantum states in a scalable solid-state Ising spin quantum computer. The spin chain is composed of identical spins 1\\/2 with the Ising interaction between the neighboring spins. The selective excitations of the spins are provided by the gradient of the external magnetic field. The protocols are

Gennady Berman; Dmitry Kamenev; Richard Kassman; Vladimir Tsifrinovich

2003-01-01

475

Scalable Neutral Atom Quantum Computer with Interaction on Demand

We propose a scalable neutral atom quantum computer with an on-demand interaction. Artificial lattice of near field optical traps is employed to trap atom qubits. Interactions between atoms can be turned off if the atoms are separated by a high enough potential barrier so that the size of the atomic wave function is much less than the interatomic distance. One-qubit gate operation is implemented by a gate control laser beam which is attached to an individual atom. Two-qubit gate operation between a particular pair of atoms is introduced by leaving these atoms in an optical lattice and making them collide so that a particular two-qubit state acquires a dynamical phase. Our proposal is feasible within existing technology developed in cold atom gas, MEMS, nanolithography, and various areas in optics.

Mikio Nakahara; Tetsuo Ohmi; Yasushi Kondo

2010-10-06

476

Continuous-Variable Quantum Computing in Optical Time-Frequency Modes Using Quantum Memories

NASA Astrophysics Data System (ADS)

We develop a scheme for time-frequency encoded continuous-variable cluster-state quantum computing using quantum memories. In particular, we propose a method to produce, manipulate, and measure two-dimensional cluster states in a single spatial mode by exploiting the intrinsic time-frequency selectivity of Raman quantum memories. Time-frequency encoding enables the scheme to be extremely compact, requiring a number of memories that are a linear function of only the number of different frequencies in which the computational state is encoded, independent of its temporal duration. We therefore show that quantum memories can be a powerful component for scalable photonic quantum information processing architectures.

Humphreys, Peter C.; Kolthammer, W. Steven; Nunn, Joshua; Barbieri, Marco; Datta, Animesh; Walmsley, Ian A.

2014-09-01

477

Quantum Memory Hierarchies: Efficient Designs to Match Available Parallelism in Quantum Computing

The assumption of maximum parallelism support for the successful realization of scalable quantum computers has led to homogeneous, ``sea-of-qubits'' architectures. The resulting architectures overcome the primary challenges of reliability and scalability at the cost of physically unacceptable system area. We find that by exploiting the natural serialization at both the application and the physical microarchitecture level of a quantum computer,

Darshan D. Thaker; Tzvetan S. Metodi; Andrew W. Cross; Isaac L. Chuang; Frederic T. Chong

2006-01-01

478

In recent years, quantum computing (QC) research has moved from the realm of theoretical physics and mathematics into real implementations. With many different potential hardware implementations, quantum computer architecture is a rich field with an opportunity to solve interesting new problems and to revisit old ones. This paper presents a QC architecture tailored to physical implementations with highly mobile and

Eric Chi; Stephen A. Lyon; Margaret Martonosi

2007-01-01

479

In recent years, quantum computing (QC) research has moved from the realm of theoretical physics and mathematics into real imple- mentations (9). With many different potential hardware implemen- tations, quantum computer architecture is a rich field with an op- portunity to solve interesting new problems and to revisit old ones. This paper presents a QC architecture tailored to physical imple-

Eric Chi; Stephen A. Lyon; Margaret Martonosi

2007-01-01

480

Fast Universal Quantum Computation with Railroad-switch Local Hamiltonians

We present two universal models of quantum computation with a time-independent, frustration-free Hamiltonian. The first construction uses 3-local (qubit) projectors, and the second one requires only 2-local qubit-qutrit projectors. We build on Feynman's Hamiltonian computer idea and use a railroad-switch type clock register. The resources required to simulate a quantum circuit with L gates in this model are O(L) small-dimensional quantum systems (qubits or qutrits), a time-independent Hamiltonian composed of O(L) local, constant norm, projector terms, the possibility to prepare computational basis product states, a running time O(L log^2 L), and the possibility to measure a few qubits in the computational basis. Our models also give a simplified proof of the universality of 3-local Adiabatic Quantum Computation.

Daniel Nagaj

2009-08-28

481

Measurement-based quantum computation and undecidable logic

We establish a connection between measurement-based quantum computation and the field of mathematical logic. We show that the computational power of an important class of quantum states called graph states, representing resources for measurement-based quantum computation, is reflected in the expressive power of (classical) formal logic languages defined on the underlying mathematical graphs. In particular, we show that for all graph state resources which can yield a computational speed-up with respect to classical computation, the underlying graphs--describing the quantum correlations of the states--are associated with undecidable logic theories. Here undecidability is to be interpreted in a sense similar to Goedel's incompleteness results, meaning that there exist propositions, expressible in the above classical formal logic, which cannot be proven or disproven.

M. Van den Nest; H. J. Briegel

2006-10-06

482

Experimental realization of a quantum game on a one-way quantum computer

We report the first demonstration of a quantum game on an all-optical one-way quantum computer. Following a recent theoretical proposal we implement a quantum version of Prisoner's Dilemma, where the quantum circuit is realized by a four-qubit box-cluster configuration and the player's local strategies by measurements performed on the physical qubits of the cluster. This demonstration underlines the strength and

Robert Prevedel; André Stefanov; Philip Walther; Anton Zeilinger

2007-01-01

483

Spin-based optical quantum computation via Pauli blocking in semiconductor quantum dots

We present a solid-state implementation of an all-optical spin-based quantum computer. Our proposal for a quantum-computing device is based on the spin degrees of freedom of electrons confined in semiconductor quantum dots, thus benefitting from relatively long coherence times. Combining Pauli blocking effects with properly tailored ultrafast laser pulses, we obtain sub-picosecond spin-dependent switching of the Coulomb interaction, which is

E. Pazy; E. Biolatti; T. Calarco; I. D'Amico; P. Zanardi; F. Rossi; P. Zoller

2003-01-01

484

Quantum picturalism for topological cluster-state computing

Topological quantum computing is a way of allowing precise quantum computations to run on noisy and imperfect hardware. One implementation uses surface codes created by forming defects in a highly-entangled cluster state. Such a method of computing is a leading candidate for large-scale quantum computing. However, there has been a lack of sufficiently powerful high-level languages to describe computing in this form without resorting to single-qubit operations, which quickly become prohibitively complex as the system size increases. In this paper we apply the category-theoretic work of Abramsky and Coecke to the topological cluster-state model of quantum computing to give a high-level graphical language that enables direct translation between quantum processes and physical patterns of measurement in a computer - a "compiler language". We give the equivalence between the graphical and topological information flows, and show the applicable rewrite algebra for this computing model. We show that this gives us a native graphical language for the design and analysis of topological quantum algorithms, and finish by discussing the possibilities for automating this process on a large scale.

Clare Horsman

2011-01-25

485

Cavity-assisted quantum computing in a silicon nanostructure

NASA Astrophysics Data System (ADS)

We present a scheme of quantum computing with charge qubits corresponding to one excess electron shared between dangling-bond pairs of surface silicon atoms that couple to a microwave stripline resonator on a chip. By choosing a certain evolution time, we propose the realization of a set of universal single- and two-qubit logical gates. Due to its intrinsic stability and scalability, the silicon dangling-bond charge qubit can be regarded as one of the most promising candidates for quantum computation. Compared to the previous schemes on quantum computing with silicon bulk systems, our scheme shows such advantages as a long coherent time and direct control and readout.

Tang, Bao; Qin, Hao; Zhang, Rong; Liu, Jin-Ming; Xue, Peng

2014-05-01

486

Fully fault tolerant quantum computation with non-deterministic gates

In certain approaches to quantum computing the operations between qubits are non-deterministic and likely to fail. For example, a distributed quantum processor would achieve scalability by networking together many small components; operations between components should assumed to be failure prone. In the logical limit of this architecture each component contains only one qubit. Here we derive thresholds for fault tolerant quantum computation under such extreme paradigms. We find that computation is supported for remarkably high failure rates (exceeding 90%) providing that failures are heralded, meanwhile the rate of unknown errors should not exceed 2 in 10^4 operations.

Ying Li; Sean D. Barrett; Thomas M. Stace; Simon C. Benjamin

2010-08-07

487

CCT: Center for Computation & TechnologyCCT: Center for Computation & Technology Shantenu Jha12*

different systems? (ALI) #12;CCT: Center for Computation & Technology Copy a File: Globus GASS if (source_url.scheme_type == GLOBUS_URL_SCHEME_GSIFTP || source_url.scheme_type == GLOBUS_URL_SCHEME_FTP ) { globus { globus_gass_transfer_requestattr_init (&source_gass_attr, source_url.scheme); globus

Wisconsin at Madison, University of

488

Quantum Computing: A new Paradigm and it's Type Theory Martin Wehr

quantum mechanical behavior for computing has been proposed by Feynman. Shor gave an algorithm complexity if quantum computed. In the paper a short introduction to quantum mechanics can be found will be applied to model the quantum parallel computation in linear logic. The notion of quantum concurrency

Gay, Simon

489

COMPUTER TECHNOLOGY FOR PRINTED NOTES RECOGNITION i -/I ii i .

' 1 COMPUTER TECHNOLOGY FOR PRINTED NOTES RECOGNITION ..2 , ..3 , .. i - /I ii i . . i and experimental testing of computer technology for printed notes recognition are described. Technology is based. Beran, T. Macek. Recognition of printed music score. In: MLDM'99, LNAI 1715, pp. 174-179. Springer

Heermann, Dieter W.

490

Computing, Information, and Communications Technology (CICT) Program Overview

NASA Technical Reports Server (NTRS)

The Computing, Information and Communications Technology (CICT) Program's goal 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 communication technologies

VanDalsem, William R.

2003-01-01

491

Secrecy, Computational Loads and Rates in Practical Quantum Cryptography

A number of questions associated with practical implementations of quantum cryp- tography systems having to do with unconditional secrecy, computational loads and effective secrecy rates in the presence of perfect and imperfect sources are discussed. The different types of unconditional secrecy, and their relationship to general com- munications security, are discussed in the context of quantum cryptography. In order to

Gerald Gilbert; Michael Hamrick

2002-01-01

492

BCD computing structures in quantum- dot cellular automata

This paper proposes a detailed design analysis of BCD computing circuit for quantum-dot cellular automata (QCA). QCA is attracting a lot of attentions due to its very small sizes and low power consumption. The primary device, a quantum-dot cell, can be used to make gates, wires, and memories as such it is the basic building block of nanotechnology circuits. Because

Maryam Taghizadeh; Mehdi Askari; Khossro Fardad

2008-01-01

493

Quantum Computing and Phase Transitions in Combinatorial Search

We introduce an algorithm for combinatorial search on quantum computers that is capable of significantly concentrating amplitude into solutions for some NP search problems, on average. This is done by exploiting the same aspects of problem structure as used by classical backtrack methods to avoid unproductive search choices. This quantum algorithm is much more likely to find solutions than the

Tad Hogg

1996-01-01

494

A Blueprint for a Topologically Fault-tolerant Quantum Computer

The advancement of information processing into the realm of quantum mechanics promises a transcendence in computational power that will enable problems to be solved which are completely beyond the known abilities of any \\

Parsa Bonderson; Sankar Das Sarma; Michael Freedman; Chetan Nayak; Michael H. Freedman

2010-01-01

495

Superradiance as a source of collective decoherence in quantum computers

NASA Astrophysics Data System (ADS)

We argue that superradiance (collective emission) due to radiative coupling of qubit states results in non-local noise, and thus introduces an error source that cannot be corrected using current models of fault-tolerant quantum computation.

Yavuz, D. D.

2014-11-01

496

Phase-noise limitations on nonlinear-optical quantum computing

Flying in the face of the long-sought-after goal of building optical quantum computers, we show that traditional approaches leveraging nonlinear-optical cross phase modulation (XPM) to construct the critical element, the ...

Dove, Justin (Justin Michael)

2014-01-01

497

Synthesis and evaluation of fault-tolerant quantum computer architectures

Fault-tolerance is the cornerstone of practical, large-scale quantum computing, pushed into its prominent position with heroic theoretical efforts. The fault-tolerance threshold, which is the component failure probability ...

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

2005-01-01

498

Towards scalable quantum communication and computation: Novel approaches and realizations

NASA Astrophysics Data System (ADS)

Quantum information science involves exploration of fundamental laws of quantum mechanics for information processing tasks. This thesis presents several new approaches towards scalable quantum information processing. First, we consider a hybrid approach to scalable quantum computation, based on an optically connected network of few-qubit quantum registers. Specifically, we develop a novel scheme for scalable quantum computation that is robust against various imperfections. To justify that nitrogen-vacancy (NV) color centers in diamond can be a promising realization of the few-qubit quantum register, we show how to isolate a few proximal nuclear spins from the rest of the environment and use them for the quantum register. We also demonstrate experimentally that the nuclear spin coherence is only weakly perturbed under optical illumination, which allows us to implement quantum logical operations that use the nuclear spins to assist the repetitive-readout of the electronic spin. Using this technique, we demonstrate more than two-fold improvement in signal-to-noise ratio. Apart from direct application to enhance the sensitivity of the NV-based nano-magnetometer, this experiment represents an important step towards the realization of robust quantum information processors using electronic and nuclear spin qubits. We then study realizations of quantum repeaters for long distance quantum communication. Specifically, we develop an efficient scheme for quantum repeaters based on atomic ensembles. We use dynamic programming to optimize various quantum repeater protocols. In addition, we propose a new protocol of quantum repeater with encoding, which efficiently uses local resources (about 100 qubits) to identify and correct errors, to achieve fast one-way quantum communication over long distances. Finally, we explore quantum systems with topological order. Such systems can exhibit remarkable phenomena such as quasiparticles with anyonic statistics and have been proposed as candidates for naturally error-free quantum computation. We propose a scheme to unambiguously detect the anyonic statistics in spin lattice realizations using ultra-cold atoms in an optical lattice. We show how to reliably read and write topologically protected quantum memory using an atomic or photonic qubit.

Jiang, Liang

499

Trapped Barium Ions for Quantum ComputationTrapped Barium Ions for Quantum Computation V.Mirgon, G of Washington Seattle WA 98195 Trapped Barium Ions for Quantum ComputationTrapped Barium Ions for Quantum

Blinov, Boris

500

Roadmap: Technical and Applied Studies Computer Technology Internet/Multimedia

Roadmap: Technical and Applied Studies Â Computer Technology Internet/Multimedia Â Bachelor Multimedia Development Tools 3 C COMT 36318 Survey of Information Security, Internet Fraud and Computer and minimum 39 upper-division credit hours #12;Roadmap: Technical and Applied Studies Â Computer Technology

Sheridan, Scott