54 research outputs found
Implementation of a Quantum Search Algorithm on a Nuclear Magnetic Resonance Quantum Computer
We demonstrate an implementation of a quantum search algorithm on a two qubit
NMR quantum computer based on cytosine.Comment: Six pages, three figure
Geometric quantum computation with NMR
The experimental realisation of the basic constituents of quantum information
processing devices, namely fault-tolerant quantum logic gates, requires
conditional quantum dynamics, in which one subsystem undergoes a coherent
evolution that depends on the quantum state of another subsystem. In
particular, the subsystem may acquire a conditional phase shift. Here we
consider a novel scenario in which this phase is of geometric rather than
dynamical origin. As the conditional geometric (Berry) phase depends only on
the geometry of the path executed it is resilient to certain types of errors,
and offers the potential of an intrinsically fault-tolerant way of performing
quantum gates. Nuclear Magnetic Resonance (NMR) has already been used to
demonstrate both simple quantum information processing and Berry's phase. Here
we report an NMR experiment which implements a conditional Berry phase, and
thus a controlled phase shift gate. This constitutes the first elementary
geometric quantum computation.Comment: Minor additions at request of referees. 4 pages revtex including 2
figures (1 eps). Nature in pres
Quiet SDS Josephson Junctions for Quantum Computing
Unconventional superconductors exhibit an order parameter symmetry lower than
the symmetry of the underlying crystal lattice. Recent phase sensitive
experiments on YBCO single crystals have established the d-wave nature of the
cuprate materials, thus identifying unambiguously the first unconventional
superconductor. The sign change in the order parameter can be exploited to
construct a new type of s-wave - d-wave - s-wave Josephson junction exhibiting
a degenerate ground state and a double-periodic current-phase characteristic.
Here we discuss how to make use of these special junction characteristics in
the construction of a quantum computer. Combining such junctions together with
a usual s-wave link into a SQUID loop we obtain what we call a `quiet' qubit
--- a solid state implementation of a quantum bit which remains optimally
isolated from its environment.Comment: 4 pages, 2 ps-figure
Entanglement in nuclear quadrupole resonance
Entangled quantum states are an important element of quantum information
techniques. We determine the requirements for states of quadrupolar nuclei with
spins >1/2 to be entangled. It was shown that entanglement is achieved at low
temperature by applying a magnetic field to a quadrupolar nuclei possess
quadrupole moments, which interacts with the electricfield gradient produced by
the charge distribution in their surroundings.Comment: 9 pages, 5 figure
Coupling Superconducting Qubits via a Cavity Bus
Superconducting circuits are promising candidates for constructing quantum
bits (qubits) in a quantum computer; single-qubit operations are now routine,
and several examples of two qubit interactions and gates having been
demonstrated. These experiments show that two nearby qubits can be readily
coupled with local interactions. Performing gates between an arbitrary pair of
distant qubits is highly desirable for any quantum computer architecture, but
has not yet been demonstrated. An efficient way to achieve this goal is to
couple the qubits to a quantum bus, which distributes quantum information among
the qubits. Here we show the implementation of such a quantum bus, using
microwave photons confined in a transmission line cavity, to couple two
superconducting qubits on opposite sides of a chip. The interaction is mediated
by the exchange of virtual rather than real photons, avoiding cavity induced
loss. Using fast control of the qubits to switch the coupling effectively on
and off, we demonstrate coherent transfer of quantum states between the qubits.
The cavity is also used to perform multiplexed control and measurement of the
qubit states. This approach can be expanded to more than two qubits, and is an
attractive architecture for quantum information processing on a chip.Comment: 6 pages, 4 figures, to be published in Natur
Automating unobtrusive personalized services in ambient media environments
The final publication is available at Springer via http://dx.doi.org/10.1007/s11042-013-1634-2In the age of ambient media, people are surrounded by lots of physical objects (media objects) for rendering the digital world in the natural environment. These media objects should interact with users in a way that is not disturbing for them. To address this issue, this work presents a design and automation strategy for augmenting the world around us with personalized ambient media services that behave in a considerate manner. That is, ambient services are capable of adjusting its obtrusiveness level (i.e., the extent to which each service intrudes the user¿s mind) by using the appropriate media objects for each user¿s situation.This work has been developed with the support of MICINN, under the project EVERYWARE TIN2010-18011, and the support of the Christian Doppler Forschungsgesellschaft and the BMWFJ, Austria.Serral Asensio, E.; Gil Pascual, M.; Valderas Aranda, PJ.; Pelechano Ferragud, V. (2014). Automating unobtrusive personalized services in ambient media environments. Multimedia Tools and Applications. 71(1):159-178. https://doi.org/10.1007/s11042-013-1634-2S159178711Bencomo N, Grace P, Flores-Cortés CA, Hughes D, Blair GS (2008) Genie: supporting the model driven development of reflective, component-based adaptive systems. In: ICSE, pp 811–814Blumendorf M, Lehmann G, Albayrak S (2010) Bridging models and systems at runtime to build adaptive user interfaces. In: Proc. of EICS 2010. ACM, pp 9–18Brown DM (2010) Communicating design: developing web site documentation for design and planning, 2nd edn. New Riders PressCalinescu R (2011) When the requirements for adaptation and high integrity meet. In: Proceedings of the 8th workshop on assurances for self-adaptive systems, ASAS ’11. ACM, New York, pp 1–4Filieri A, Ghezzi C, Tamburrelli G (2011) Run-time efficient probabilistic model checking. In: Proceedings of the 33rd International Conference on Software Engineering, ICSE ’11. ACM, New York, pp 341–350Gershenfeld N, Krikorian R, Cohen D (2004) The internet of things. Sci Am 291(4):46–51Gibbs WW (2005) Considerate computing. Sci Am 292(1):54–61Gulliksen J, Goransson B, Boivie I, Blomkvist S, Persson J, Cajander A (2003) Key principles for user-centred systems design. Behav Inform Technol 22:397–409Hinckley K, Horvitz E (2001) Toward more sensitive mobile phones. In: Proc. of the UIST ’01, pp 191–192Ho J, Intille SS (2005) Using context-aware computing to reduce the perceived burden of interruptions from mobile devices. In: Proc. of CHI ’05. ACM, pp 909–918Horvitz E, Kadie C, Paek T, Hovel D (2003) Models of attention in computing and communication: from principles to applications. Commun ACM 46:52–59Ju W, Leifer L (2008) The design of implicit interactions: making interactive systems less obnoxious. Des Issues 24(3):72–84Kortuem G, Kawsar F, Fitton D, Sundramoorthy V (2010) Smart objects as building blocks for the internet of things. IEEE Internet Comput 14(1):44–51Lewis JR (1995) Ibm computer usability satisfaction questionnaires: psychometric evaluation and instructions for use. Int J Hum Comput Interact 7(1):57–78Lugmayr A, Risse T, Stockleben B, Laurila K, Kaario J (2009) Semantic ambient media—an introduction. Multimed Tools Appl 43(3):337–359Mattern F (2003) From smart devices to smart everyday objects. In: Proc. Smart Objects Conf. (SOC 03). Springer, pp 15–16Morin B, Barais O, Jezequel JM, Fleurey F, Solberg A (2009) Models run.time to support dynamic adaptation. Comput 42(10):44–51Nelson L, Churchill EF (2005) User experience of physical-digital object systems: implications for representation and infrastructure. Paper presented at smart object systems workshop, in cojunction with ubicomp 2005Paternò F (2002) Concurtasktrees: an engineered approach to model-based design of interactive systems. In: L.E. Associates (ed) The handbook of analysis for human-computer interaction, pp 483–500Paternò F (2003) From model-based to natural development. HCI International, pp 592–596Ramchurn SD, Deitch B, Thompson MK, Roure DCD, Jennings NR, Luck M (2004) Minimising intrusiveness in pervasive computing environments using multi-agent negotiation. MobiQuitous ’04, pp 364–372Runeson P, Höst M (2009) Guidelines for conducting and reporting case study research in software engineering. Empir Softw Eng 14(2):131–164Schmidt A (2000) Implicit human computer interaction through context. Pers Technol 4(2–3):191–199Serral E, Valderas P, Pelechano V (2010) Supporting runtime system evolution to adapt to user behaviour. In: Proc. of CAiSE’10, pp 378–392Serral E, Valderas P, Pelechano V (2010) Towards the model driven development of context-aware pervasive systems. PMC 6(2):254–280Siegemund F (2004) A context-aware communication platform for smart objects. In: Proc of the int conf on pervasive computing. Springer, pp 69–86Streitz NA, Rocker C, Prante T, Alphen Dv, Stenzel R, Magerkurth C (2005) Designing smart artifacts for smart environments. Comput 38(3):41–49. doi: 10.1109/MC.2005.92Thiesse F, Kohler M (2008) An analysis of usage-based pricing policies for smart products. Electron Mark 18(3):232–241. doi: 10.1080/10196780802265751Vastenburg MH, Keyson DV, de Ridder H (2008) Considerate home notification systems: a field study of acceptability of notifications in the home. 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Quantum Computing
Quantum mechanics---the theory describing the fundamental workings of
nature---is famously counterintuitive: it predicts that a particle can be in
two places at the same time, and that two remote particles can be inextricably
and instantaneously linked. These predictions have been the topic of intense
metaphysical debate ever since the theory's inception early last century.
However, supreme predictive power combined with direct experimental observation
of some of these unusual phenomena leave little doubt as to its fundamental
correctness. In fact, without quantum mechanics we could not explain the
workings of a laser, nor indeed how a fridge magnet operates. Over the last
several decades quantum information science has emerged to seek answers to the
question: can we gain some advantage by storing, transmitting and processing
information encoded in systems that exhibit these unique quantum properties?
Today it is understood that the answer is yes. Many research groups around the
world are working towards one of the most ambitious goals humankind has ever
embarked upon: a quantum computer that promises to exponentially improve
computational power for particular tasks. A number of physical systems,
spanning much of modern physics, are being developed for this task---ranging
from single particles of light to superconducting circuits---and it is not yet
clear which, if any, will ultimately prove successful. Here we describe the
latest developments for each of the leading approaches and explain what the
major challenges are for the future.Comment: 26 pages, 7 figures, 291 references. Early draft of Nature 464, 45-53
(4 March 2010). Published version is more up-to-date and has several
corrections, but is half the length with far fewer reference
Discovery of potent, novel, non-toxic anti-malarial compounds via quantum modelling, virtual screening and in vitro experimental validation
<p>Abstract</p> <p>Background</p> <p>Developing resistance towards existing anti-malarial therapies emphasize the urgent need for new therapeutic options. Additionally, many malaria drugs in use today have high toxicity and low therapeutic indices. Gradient Biomodeling, LLC has developed a quantum-model search technology that uses quantum similarity and does not depend explicitly on chemical structure, as molecules are rigorously described in fundamental quantum attributes related to individual pharmacological properties. Therapeutic activity, as well as toxicity and other essential properties can be analysed and optimized simultaneously, independently of one another. Such methodology is suitable for a search of novel, non-toxic, active anti-malarial compounds.</p> <p>Methods</p> <p>A set of innovative algorithms is used for the fast calculation and interpretation of electron-density attributes of molecular structures at the quantum level for rapid discovery of prospective pharmaceuticals. Potency and efficacy, as well as additional physicochemical, metabolic, pharmacokinetic, safety, permeability and other properties were characterized by the procedure. Once quantum models are developed and experimentally validated, the methodology provides a straightforward implementation for lead discovery, compound optimizzation and <it>de novo </it>molecular design.</p> <p>Results</p> <p>Starting with a diverse training set of 26 well-known anti-malarial agents combined with 1730 moderately active and inactive molecules, novel compounds that have strong anti-malarial activity, low cytotoxicity and structural dissimilarity from the training set were discovered and experimentally validated. Twelve compounds were identified <it>in silico </it>and tested <it>in vitro</it>; eight of them showed anti-malarial activity (IC50 ≤ 10 μM), with six being very effective (IC50 ≤ 1 μM), and four exhibiting low nanomolar potency. The most active compounds were also tested for mammalian cytotoxicity and found to be non-toxic, with a therapeutic index of more than 6,900 for the most active compound.</p> <p>Conclusions</p> <p>Gradient's metric modelling approach and electron-density molecular representations can be powerful tools in the discovery and design of novel anti-malarial compounds. Since the quantum models are agnostic of the particular biological target, the technology can account for different mechanisms of action and be used for <it>de novo </it>design of small molecules with activity against not only the asexual phase of the malaria parasite, but also against the liver stage of the parasite development, which may lead to true causal prophylaxis.</p
Digitizing the Building Site for Restoration Projects: From ALM Technologies to Innovative Material Scenarios.
The ongoing synergy between the digitization of the building process and new paradigms related to the production of architectural constructions and building elements addresses the definition of new scenarios that are worth inves- tigating. The recurring question, indeed, is how the most advanced digital tech- niques for material production can have a tangible impact on architecture and its morphological languages. In the field of building design, the chance to turn digital data into matter repre- sents a key point to deal with, in order to demonstrate the possibility to transfer actual benefits from other sectors related to the construction industry. This new technical asset links the digitization of processes with the industrialization of building products. The present research aims at deepening the opportunity of Additive Layer Manufacturing technologies, alongside the current Building Information Modeling and parametric design methods, to push further the hitherto established decision- making rules and the conventional building site organization, towards sustainable development
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