Tesis sobre el tema "Quantum computer"
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Kilin, S. Ya, J. Wrachtrup y kilin@ifanbel bas-net by. "Diamond Quantum Computer". ESI preprints, 2000. ftp://ftp.esi.ac.at/pub/Preprints/esi950.ps.
Texto completoMosca, Michele. "Quantum computer algorithms". Thesis, University of Oxford, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301184.
Texto completoWallace, Julia. "Quantum computer software". Thesis, University of Exeter, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.369975.
Texto completoGiesecke, Normen. "Ternary quantum logic". PDXScholar, 2006. https://pdxscholar.library.pdx.edu/open_access_etds/4092.
Texto completoPapanikolaou, Nikolaos K. "Model checking quantum protocols". Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/2236/.
Texto completoGeorge, R. E. "Towards a silicon quantum computer". Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.599362.
Texto completoChong, Henry H. W. 1974. "Toward a personal quantum computer". Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/42797.
Texto completoIncludes bibliographical references (p. 115-118).
by Henry H.W. Chong.
M.Eng.
Delbecque, Yannick. "Quantum games as quantum types". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=40670.
Texto completoNous présentons dans cette thèse un nouveau modèlepour les langages de programmation quantique. Notre modèle est uneadaptation de la sémantique de jeux probabilistes définie par Danos etHarmer: nous y ajoutons des stratégies quantiquespour permettre la représentation des états et des opérations quantiques.Nous établissons quelques propriétés de base de ces stratégies. Cespropriétés sont ensuite utilisées pour construire des sémantiquesdénotationnelles pour trois langages de programmation quantique. Le premierlangage est une formalisation du calcul par mesures proposé par Danoset al. Les deux autres langages sont nouveaux: ce sont deslangages quantiques d'ordre supérieur dont la syntaxe a été construiteà partir d'observations expliquant l'échec des tentatives précédentespour construire une sémantique dénotationnelle pour de tels langages. La sémantique de jeux présentée dans cette thèseest la première sémantique dénotationnelle pour de telslambda-calculs équipés de types et d'opérations supplémentairespermettant la programmation d'algorithmes quantiques. Les résultatsprésentés valident les deux approches différentes utilitées dans laconception de ces deux nouveaux languages d'ordre supérieur: une premièreoù les états quantiques sont indirectement accessibles via desréférences et une seconde où ils sont introduit directement comme desconstantes dans le langage. Les stratégies quantiques présentéespermettent de comprendre les contraintes devant êtreimposées aux systèmes de type quantique comportant des types d'ordresupérieurs. La contrainte la plus importante est le fait que l'abstractionsur une partie d'un état quantique comportant plusieurs qbits inconnus doitêtre prohibée. Les stratégies quantiques constituent un nouveau modèle mathématique quidécrit l'interaction entre les données classiques et quantiques par desdialogues entre système et environnement. L'interaction entre les differentespar
Mims, Mark McGrew. "Dynamical stability of quantum algorithms /". Full text (PDF) from UMI/Dissertation Abstracts International, 2000. http://wwwlib.umi.com/cr/utexas/fullcit?p3004342.
Texto completoJanzing, Dominik. "Computer science approach to quantum control". Karlsruhe : Univ.-Verl. Karlsruhe, 2006. http://www.uvka.de/univerlag/volltexte/2006/175/.
Texto completoHansen, Rasmus Hvass. "Towards the nuclear spin quantum computer". Thesis, University of Oxford, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.442465.
Texto completoMaguire, Yael G. 1975. "Towards a table top quantum computer". Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/61842.
Texto completoIncludes bibliographical references (leaves 135-139).
In the early 1990s, quantum computing proved to be an enticing theoretical possibility but a extremely difficult experimental challenge. Two advances have made experimental quantum computing demonstrable: Quantum error correction; and bulk, thermal quantum computing using nuclear magnetic resonance (NMR). Simple algorithms have been implemented on large, commercial NMR spectrometers that are expensive and cumbersome. The goal of this project is to construct a table-top quantum computer that can match and eventually exceed the performance of commercial machines. This computer should be an inexpensive, easy-to-use machine that can be considered more a computer than its "supercomputer" counterparts. For this thesis, the goal is to develop a low-cost, table-top quantum computer capable of implementing simple quantum algorithms demonstrated thus far in the community, but is also amenable to the many scaling issues of practical quantum computing. Understanding these scaling issues requires developing a theoretical understanding of the signal enhancement techniques and fundamental noise sources of this powerful but delicate system. Complementary to quantum computing, this high performance but low cost NMR machine will be useful for a number of medical, low cost sensing and tagging applications due the unique properties of NMR: the ability to sense and manipulate the information content of materials on macroscopic and microscopic scales.
Yael G. Maguire.
S.M.
Lukac, Martin. "Quantum Inductive Learning and Quantum Logic Synthesis". PDXScholar, 2009. https://pdxscholar.library.pdx.edu/open_access_etds/2319.
Texto completoBabar, Zunaira. "Quantum error correction codes". Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/380165/.
Texto completoHuang, Wei-Han 1979. "Instrumentation for quantum computers". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/30104.
Texto completoIncludes bibliographical references (p. 209-215).
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 how quantum circuits require extremely precise control instrumentation for pulsed excitation. In this thesis, we develop two general-purpose, low-cost pulse programmers and two Class E power amplifiers, designed for precise control of qubits and complex pulse excitation. The first-generation pulse programmer has timing resolutions of 235 ns, while the second-generation one has resolutions of 10 ns. The Class E power amplifier has [mu]s transient response times, a high quality-factor, and a small form factor. The verification of the pulse programmer and the Class E power amplifier is demonstrated using a customized nuclear quadrupole resonance (NQR) spectrom- eter, which incorporates both devices. The two devices control the generation of RF pulses used in NQR experiments on paradichlorobenzene (C₆H₄C₁₂) and sodium nitrite (NaNO₂). The NQR signals originating from ¹⁴N in sodium nitrite and from ³⁵Cl in paradichlorobenzene are measured using the NQR spectrometer. The pulse programmer and the Class E power amplifier represent first steps towards development of practical NMR quantum computers.
by Wei-Han Huang.
S.M.
Brandhorst-Satzkorn, Johan. "A Review of Freely Available Quantum Computer Simulation Software". Thesis, Linköpings universitet, Matematik och tillämpad matematik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-78650.
Texto completoArdeshir-Larijani, Ebrahim. "Automated equivalence checking of quantum information systems". Thesis, University of Warwick, 2014. http://wrap.warwick.ac.uk/63940/.
Texto completoZuccon, Guido. "Document ranking with quantum probabilities". Thesis, University of Glasgow, 2012. https://eprints.qut.edu.au/69287/1/zuccon2012b.pdf.
Texto completoZuccon, Guido. "Document ranking with quantum probabilities". Thesis, University of Glasgow, 2012. http://theses.gla.ac.uk/3463/.
Texto completoDevitt, Simon John. "Quantum information engineering : concepts to quantum technologies /". Connect to thesis, 2007. http://eprints.unimelb.edu.au/archive/00003925.
Texto completoCross, Andrew W. (Andrew William) 1979. "Fault-tolerant quantum computer architectures using hierarchies of quantum error-correcting codes". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44407.
Texto completoIncludes bibliographical references (p. 221-238).
Quantum computers have been shown to efficiently solve a class of problems for which no efficient solution is otherwise known. Physical systems can implement quantum computation, but devising realistic schemes is an extremely challenging problem largely due to the effect of noise. A quantum computer that is capable of correctly solving problems more rapidly than modern digital computers requires some use of so-called fault-tolerant components. Code-based fault-tolerance using quantum error-correcting codes is one of the most promising and versatile of the known routes for fault-tolerant quantum computation. This dissertation presents three main, new results about code-based fault-tolerant quantum computer architectures. The first result is a large new family of quantum codes that go beyond stabilizer codes, the most well-studied family of quantum codes. Our new family of codeword stabilized codes contains all known codes with optimal parameters. Furthermore, we show how to systematically find, construct, and understand such codes as a pair of codes: an additive quantum code and a classical (nonlinear) code. Second, we resolve an open question about universality of so-called transversal gates acting on stabilizer codes. Such gates are universal for classical fault-tolerant computation, but they were conjectured to be insufficient for universal fault-tolerant quantum computation. We show that transversal gates have a restricted form and prove that some important families of them cannot be quantum universal. This is strong evidence that so-called quantum software is necessary to achieve universality, and, therefore, fault-tolerant quantum computer architecture is fundamentally different from classical computer architecture. Finally, we partition the fault-tolerant design problem into levels of a hierarchy of concatenated codes and present methods, compatible with rigorous threshold theorems, for numerically evaluating these codes.
(cont.) The methods are applied to measure inner error-correcting code performance, as a first step toward elucidation of an effective fault-tolerant quantum computer architecture that uses no more than a physical, inner, and outer level of coding. Of the inner codes, the Golay code gives the highest pseudothreshold of 2 x 10-3. A comparison of logical error rate and overhead shows that the Bacon-Shor codes are competitive with Knill's C₄/C₆ scheme at a base error rate of 10⁻⁴.
by Andrew W. Cross.
Ph.D.
Raynaud, Guillaume. "Fibred contextual quantum physics". Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/1685/.
Texto completoDesrosiers, Simon Pierre. "Quantum entropic security". Thesis, McGill University, 2009. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95620.
Texto completoUne généralisation complète des notions de sécurité entropique et d'indistinguabilitéentropique, telles que définies par Russell et Wang puis par Dodis et Smith, aumonde quantique est présentée. Aucune autre hypothèse qu'une borne inférieure surl'incertitude de l'adversaire, incertitude quantifiée par la notion de min-entropie conditionellequantique telle que définie par Renner, n'est présumée. Ce modèle permettoute forme de corrélation ou d'intrication entre l'adversaire et l'émetteur du message.Une démonstration de l'équivalence entre ces deux notions de sécurité est présentéequi est beaucoup plus simple que ce qui était connue au-paravant. Cette nouvellesimplicité est une contribution notable. Deux chiffres sont aussi généralisés à ce nouveaumodèle de sécurité et leur sécurité est démontrée. La taille de la clef requise afind'assurer la sécurité de ces deux chiffres est exactement la même que celle requise parleur équivalent classique. Ces chiffres sont sécuritaires même en présence d'intricationentre l'adversaire et l'émetteur, ce qui est, autant que nous le sachions, une premièresans requérir une sécurité parfaite.
Grattage, Jonathan James. "A functional quantum programming language". Thesis, University of Nottingham, 2006. http://eprints.nottingham.ac.uk/10250/.
Texto completoBotsinis, Panagiotis. "Quantum-assisted multi-user wireless systems". Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/381235/.
Texto completoNicholson, Lori Eileen. "Quantum Algorithm Animator". NSUWorks, 2010. http://nsuworks.nova.edu/gscis_etd/262.
Texto completoBarenco, Adriano. "Quantum computation". Thesis, University of Oxford, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360152.
Texto completoCopsey, Dean Elbert. "Designing scalable quantum computer architectures : layout and initialization /". For electronic version search Digital dissertations database. Restricted to UC campuses. Access is free to UC campus dissertations, 2005. http://uclibs.org/PID/11984.
Texto completoMower, Jacob. "Photonic quantum computers and communication systems". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/103851.
Texto completoCataloged from PDF version of thesis.
Includes bibliographical references (pages 123-137).
Quantum information processors have been proposed to solve classically intractable or unsolvable problems in computing, sensing, and secure communication. There has been growing interest in photonic implementations of quantum processors as they offer relatively long coherence lengths, precise state manipulation, and efficient measurement. In this thesis, we first present experimental techniques to generate on-chip, photonic quantum processors and then discuss protocols for fast and secure quantum communication. In particular, we describe how -to combine the outputs of multiple stochastic single-photon sources using a photonic integrated circuit to generate an efficient source of single photons. We then show designs for silicon-based quantum photonic processors that can be programmed to implement a large class of existing quantum algorithms and can lead to quicker testing of new algorithms than was previously possible. We will then present the integration of large numbers of high-efficiency, low-timing jitter single-photon detectors onto a silicon photonic integrated circuit. To conclude, we will present a quantum key distribution protocol that uses the robust temporal degree of freedom of entangled photons to enable fast, secure key exchange, as well as experimental results for implementing key distribution protocols using silicon photonic integrated circuits.
by Jacob Mower.
Ph. D.
Anderzén, Rodenkirchen Sven y Marcus Granström. "Performance evaluation of quantum Fourier transform on a modern quantum device". Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-229682.
Texto completoKvantberäkningar har under de senaste decennierna gått från att vara ett teoretiskt koncept till att implementeras på riktiga enheter. En stor utmaning finns dock kvar; kvantdatorernas känslighet för störningar. Under de senaste åren har stora framsteg gjorts för att minska påverkan av störningar i kvantberäkningar vilket öppnar upp för frågan; hur bra fungerar en icke-felrättande kvantberäkning på en modern kvantdator? I detta arbete utför vi kvant-Fouriertransform, en vanlig operation i många kvantalgoritmer, på den riktig kvantdatorn IBMQX4. Vi jämför resultaten från den riktiga kvantdatorn mot felfria simuleringar och mäter den inverkan felen haft på perioden. Vi visar att även om det är möjligt att urskilja ett korrekt resultat för triviala probleminstanser så är fel orsakat av störningar fortfarande för stort för att erhålla ett korrekt resultat för icke-triviala problem. Vi fastställer att tekniker för felkorrigering inom kvantberäkningar är en nödvändighet för icke-triviala probleminstanser.
Venkatraman, Dheera. "Quantum-mimetic imaging". Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/97762.
Texto completoThis electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references (pages 139-146).
Many recent experiments have explored the use of nonclassical states of light to perform imaging or sensing. Although these experiments require quantum descriptions of light to explain their behavior, the advantages they claim are not necessarily unique to quantum light. This thesis explores the underlying principles behind two of those imaging techniques and realizes classical experiments that demonstrate properties similar to their quantum counterparts. The principal contributions of this thesis in the preceding quantum-mimetic imaging paradigm are the experimental implementation of phase-conjugate optical coherence tomography and phase-sensitive ghost imaging, two experiments whose quantum counterparts utilize phase-sensitive light with nonclassical strength. This thesis also explores the use of compressed sensing to further speed up acquisition of ghost imaging. Finally, a new paradigm inspired by compressed sensing is demonstrated, in which high-quality depth and reflectivity images are simultaneously captured using only the first photon arrival at each pixel. This paradigm is also extended to the case of single-photon APD arrays which may offer few-photon low-light imaging capabilities beyond what is possible with current camera technologies.
by Dheera Venkatraman.
Ph. D.
Eldar, Yonina Chana 1973. "Quantum signal processing". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/16805.
Texto completoIncludes bibliographical references (p. 337-346).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Quantum signal processing (QSP) as formulated in this thesis, borrows from the formalism and principles of quantum mechanics and some of its interesting axioms and constraints, leading to a novel paradigm for signal processing with applications in areas ranging from frame theory, quantization and sampling methods to detection, parameter estimation, covariance shaping and multiuser wireless communication systems. The QSP framework is aimed at developing new or modifying existing signal processing algorithms by drawing a parallel between quantum mechanical measurements and signal processing algorithms, and by exploiting the rich mathematical structure of quantum mechanics, but not requiring a physical implementation based on quantum mechanics. This framework provides a unifying conceptual structure for a variety of traditional processing techniques, and a precise mathematical setting for developing generalizations and extensions of algorithms. Emulating the probabilistic nature of quantum mechanics in the QSP framework gives rise to probabilistic and randomized algorithms. As an example we introduce a probabilistic quantizer and derive its statistical properties. Exploiting the concept of generalized quantum measurements we develop frame-theoretical analogues of various quantum-mechanical concepts and results, as well as new classes of frames including oblique frame expansions, that are then applied to the development of a general framework for sampling in arbitrary spaces. Building upon the problem of optimal quantum measurement design, we develop and discuss applications of optimal methods that construct a set of vectors.
(cont.) We demonstrate that, even for problems without inherent inner product constraints, imposing such constraints in combination with least-squares inner product shaping leads to interesting processing techniques that often exhibit improved performance over traditional methods. In particular, we formulate a new viewpoint toward matched filter detection that leads to the notion of minimum mean-squared error covariance shaping. Using this concept we develop an effective linear estimator for the unknown parameters in a linear model, referred to as the covariance shaping least-squares estimator. Applying this estimator to a multiuser wireless setting, we derive an efficient covariance shaping multiuser receiver for suppressing interference in multiuser communication systems.
by Yonina Chana Eldar.
Ph.D.
Patino, Alberto. "Reversible Logic Synthesis Using a Non-blocking Order Search". PDXScholar, 2010. https://pdxscholar.library.pdx.edu/open_access_etds/162.
Texto completoHnatenko, O. S. "Quantum computing. Quantum information technologies as the basis for future learning platforms". Thesis, ISMA University of Applied Science, Riga, Latvia, 2021. https://openarchive.nure.ua/handle/document/16270.
Texto completoWelch, Jonathan M. "On the Synthesis of Quantum Circuits for Diagonal Operators in Quantum Computation". Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:23845468.
Texto completoEngineering and Applied Sciences - Applied Physics
Schneider, Scott (Scott David) 1978. "Quantum Systems Simulator". Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/86873.
Texto completoIncludes bibliographical references (leaf 41).
by Scott Schneider.
M.Eng.and S.B.
S.B.
Janzing, Dominik [Verfasser]. "Computer science approach to quantum control / von Dominik Janzing". Karlsruhe : Univ.-Verl. Karlsruhe, 2006. http://d-nb.info/982614721/34.
Texto completoCox, Hazel. "The quantum-mechanical three-body problem using computer algebra". Thesis, University of York, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239780.
Texto completoCross, Andrew W. (Andrew William) 1979. "Synthesis and evaluation of fault-tolerant quantum computer architectures". Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/30175.
Texto completoIncludes bibliographical references (p. 241-247).
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 below which arbitrarily reliable quantum computation becomes possible, is one standard quality measure of fault-tolerant designs based on recursive simulation. However, there is a gulf between theoretical achievements and the physical reality and complexity of envisioned quantum computing systems. This thesis takes a step toward bridging that gap. We develop a new experimental method for estimating fault-tolerance thresholds that applies to realistic models of quantum computer architectures, and demonstrate this technique numerically. We clarify a central problem for experimental approaches to fault-tolerance evaluation--namely, distinguishing between potentially optimistic pseudo-thresholds and actual thresholds that determine scalability. Next, we create a system architecture model for the trapped-ion quantum computer, discuss potential layouts, and numerically estimate the fault-tolerance threshold for this system when it is constrained to a local layout. Finally, we place the problem of evaluation and synthesis of fault-tolerant quantum computers into a broader framework by considering a software architecture for quantum computer design.
by Andrew W. Cross.
S.M.
SILVA, Adenilton José da. "Artificial neural network architecture selection in a quantum computer". UNIVERSIDADE FEDERAL DE PERNAMBUCO, 2015. https://repositorio.ufpe.br/handle/123456789/15011.
Texto completoMade available in DSpace on 2016-01-27T17:25:47Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) tese Adenilton José da Silva.pdf: 4885126 bytes, checksum: d2bade12d15d6626962f244aebd5678d (MD5) Previous issue date: 2015-06-26
CNPq
Miniaturisation of computers components is taking us from classical to quantum physics domain. Further reduction in computer components size eventually will lead to the development of computer systems whose components will be on such a small scale that quantum physics intrinsic properties must be taken into account. The expression quantum computation and a first formal model of a quantum computer were first employed in the eighties. With the discovery of a quantum algorithm for factoring exponentially faster than any known classical algorithm in 1997, quantum computing began to attract industry investments for the development of a quantum computer and the design of novel quantum algorithms. For instance, the development of learning algorithms for neural networks. Some artificial neural networks models can simulate an universal Turing machine, and together with learning capabilities have numerous applications in real life problems. One limitation of artificial neural networks is the lack of an efficient algorithm to determine its optimal architecture. The main objective of this work is to verify whether we can obtain some advantage with the use of quantum computation techniques in a neural network learning and architecture selection procedure. We propose a quantum neural network, named quantum perceptron over a field (QPF). QPF is a direct generalisation of a classical perceptron which addresses some drawbacks found in previous models for quantum perceptrons. We also present a learning algorithm named Superposition based Architecture Learning algorithm (SAL) that optimises the neural network weights and architectures. SAL searches for the best architecture in a finite set of neural network architectures and neural networks parameters in linear time over the number of examples in the training set. SAL is the first quantum learning algorithm to determine neural network architectures in linear time. This speedup is obtained by the use of quantum parallelism and a non linear quantum operator.
A miniaturização dos componentes dos computadores está nos levando dos domínios da física clássica aos domínios da física quântica. Futuras reduções nos componentes dos computadores eventualmente levará ao desenvolvimento de computadores cujos componentes estarão em uma escala em que efeitos intrínsecos da física quântica deverão ser considerados. O termo computação quântica e um primeiro modelo formal de computação quântica foram definidos na década de 80. Com a descoberta no ano de 1997 de um algoritmo quântico para fatoração exponencialmente mais rápido do que qualquer algoritmo clássico conhecido a computação quântica passou a atrair investimentos de diversas empresas para a construção de um computador quântico e para o desenvolvimento de algoritmos quânticos. Por exemplo, o desenvolvimento de algoritmos de aprendizado para redes neurais. Alguns modelos de Redes Neurais Artificiais podem ser utilizados para simular uma máquina de Turing universal. Devido a sua capacidade de aprendizado, existem aplicações de redes neurais artificiais nas mais diversas áreas do conhecimento. Uma das limitações das redes neurais artificiais é a inexistência de um algoritmo com custo polinomial para determinar a melhor arquitetura de uma rede neural. Este trabalho tem como objetivo principal verificar se é possível obter alguma vantagem no uso da computação quântica no processo de seleção de arquiteturas de uma rede neural. Um modelo de rede neural quântica denominado perceptron quântico sobre um corpo foi proposto. O perceptron quântico sobre um corpo é uma generalização direta de um perceptron clássico que resolve algumas das limitações em modelos de redes neurais quânticas previamente propostos. Um algoritmo de aprendizado denominado algoritmo de aprendizado de arquitetura baseado no princípio da superposição que otimiza pesos e arquitetura de uma rede neural simultaneamente é apresentado. O algoritmo proposto possui custo linear e determina a melhor arquitetura em um conjunto finito de arquiteturas e os parâmetros da rede neural. O algoritmo de aprendizado proposto é o primeiro algoritmo quântico para determinar a arquitetura de uma rede neural com custo linear. O custo linear é obtido pelo uso do paralelismo quântico e de um operador quântico não linear.
Feinstein, David Dov Yehuda. "Computer-aided-design methods for emerging quantum computing technologies". Ann Arbor, Mich. : ProQuest, 2008. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3303775.
Texto completoTitle from PDF title page (viewed Mar. 16, 2009). Source: Dissertation Abstracts International, Volume: 69-03, Section: B, page: 1733. Adviser: Mitchell A. Thornton. Includes bibliographical references.
Chung, Hyeyoun M. Eng Massachusetts Institute of Technology. "The study of entangled states in quantum computation and quantum information science". Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45991.
Texto completoIncludes bibliographical references (p. 267-274).
This thesis explores the use of entangled states in quantum computation and quantum information science. Entanglement, a quantum phenomenon with no classical counterpart, has been identified as an important and quantifiable resource in many areas of theoretical quantum information science, including quantum error correction, quantum cryptography, and quantum algorithms. We first investigate the equivalence classes of a particular class of entangled states (known as graph states due to their association with mathematical graphs) under local operations. We prove that for graph states corresponding to graphs with neither cycles of length 3 nor 4, the equivalence classes can be characterized in a very simple way. We also present software for analyzing and manipulating graph states. We then study quantum error-correcting codes whose codewords are highly entangled states. An important area of investigation concerning QECCs is to determine which resources are necessary in order to carry out any computation on the code to an arbitrary degree of accuracy, while simultaneously maintaining a high degree of resistance to noise. We prove that transversal gates, which are designed to prevent the propagation of errors through a system, are insufficient to achieve universal computation on almost all QECCs. Finally, we study the problem of creating efficient quantum circuits for creating entangling measurements.
(cont.) Entangling measurements can be used to harness the apparent extra computing power of quantum systems by allowing us to extract information about the global, collective properties of a quantum state using local measurements. We construct explicit quantum circuits that create entangling measurements, and show that these circuits scale polynomially in the input parameters.
by Hyeyoun Chung.
M.Eng.
Mayfield, James L. IV. "A Parameterized Framework for Quantum Computation". University of Cincinnati / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1342543546.
Texto completoGreen, Alexander S. "Towards a formally verified functional quantum programming language". Thesis, University of Nottingham, 2010. http://eprints.nottingham.ac.uk/11457/.
Texto completoWilliams, Benjamin S. (Benjamin Stanford) 1974. "Terahertz quantum cascade lasers". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/17012.
Texto completoIncludes bibliographical references (p. 297-310).
This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
The development of the terahertz frequency range has long been impeded by the relative dearth of compact, coherent radiation sources of reasonable power. This thesis details the development of quantum cascade lasers (QCLs) that operate in the terahertz with photon energies below the semiconductor Reststrahlen band. Photons are emitted via electronic intersubband transitions that take place entirely within the conduction band, where the wavelength is chosen by engineering the well and barrier widths in multiple-quantum-well heterostructures. Fabrication of such long wavelength lasers has traditionally been challenging, since it is difficult to obtain a population inversion between such closely spaced energy levels, and because traditional dielectric waveguides become extremely lossy due to free carrier absorption. This thesis reports the development of terahertz QCLs in which the lower radiative state is depopulated via resonant longitudinal-optical phonon scattering. This mechanism is efficient and temperature insensitive, and provides protection from thermal backfilling due to the large energy separation between the lower radiative state and the injector. Both properties are important in allowing higher temperature operation at longer wavelengths. Lasers using a surface plasmon based waveguide grown on a semi-insulating (SI) GaAs substrate were demonstrated at 3.4 THz in pulsed mode up to 87 K, with peak collected powers of 14 mW at 5 K, and 4 mW at 77 K.
Additionally, the first terahertz QCLs have been demonstrated that use metalmetal waveguides, where the mode is confined between metal layers placed immediately above and below the active region. These devices have confinement factors close to unity, and are expected to be advantageous over SI-surface-plasmon waveguides, especially at long wavelengths. Such a waveguide was used to obtain lasing at 3.8 THz in pulsed mode up to a record high temperature of 137 K, whereas similar devices fabricated in SI-surface-plasmon waveguides had lower maximum lasing temperatures due to the higher losses and lower confinement factors. This thesis describes the theory, design, fabrication, and testing of terahertz quantum cascade laser devices. A summary of theory relevant to design is presented, including intersubband radiative transitions and gain, intersubband scattering, and coherent resonant tunneling transport using a tight-binding density matrix model. Analysis of the effects of the complex heterostructure phonon spectra on terahertz QCL design are considered. Calculations of the properties of various terahertz waveguides are presented and compared with experimental results. Various fabrication methods have been developed, including a robust metallic wafer bonding technique used to fabricate metal-metal waveguides. A wide variety of quantum cascade structures, both lasing and non-lasing, have been experimentally characterized, which yield valuable information about the transport and optical properties of terahertz devices. Finally, prospects for higher temperature operation of terahertz QCLs are considered.
by Benjamin S. Williams.
Ph.D.
Preda, Daniel C. (Daniel Ciprian) 1979. "Quantum query complexity revisited". Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29689.
Texto completoIncludes bibliographical references (leaves 30-31).
In this thesis, we look at the polynomial method for quantum query complexity and relate it to the BQPA = PA question for a random oracle A. We will also look at some open problems and improve some bounds relating classical and quantum complexity.
by Daniel C. Preda.
M.Eng.and S.B.
Smith, Adam (Adam Davidson) 1977. "Multi-party quantum computation". Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/86782.
Texto completoWilson, Frederick Wilson. "Simulating atomic-scale dopant placement for a solid-state quantum computer". Thesis, The University of Sydney, 2006. https://hdl.handle.net/2123/28160.
Texto completoMalik, Zahid. "Computer simulation of fundamental quantum processes using the Bohm theory". Thesis, University of Portsmouth, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.238808.
Texto completoDixon, Alexander Robert. "High speed and actively stabilised quantum key distribution". Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.609865.
Texto completo