Simulación clásica de un algoritmo cuántico

Classical computing there are multiple algorithms to efficiently locate a certain element within a disorganized database; however, quantum computing can be applied more assertively in the face of problems in which it is complicated to verify a solution and at the same time to test multiple and possible solutions. Therefore, this article presents an introduction to Quantum Computing, developing some concepts of quantum formalism, and then approach Grover's algorithm which exploits the principle of superposition to the maximum. Finally, a classic simulation of this algorithm is performed, and the results obtained are compared with classical algorithms such as sequential search and binary search method. A 95% is obtained as a result of greater effectiveness in times -when solving the same search-, revealing the potential advantages of quantum computing.En la computación clásica existen múltiples algoritmos para localizar de manera eficiente un determinado elemento dentro de una base de datos desorganizada; sin embargo, la computación cuántica puede aplicarse de manera más asertiva frente a tales problemas cuando es complejo verificar una solución y a la vez probar múltiples y posibles soluciones. Por lo anterior, en este artículo se presenta una introducción a la Computación Cuántica -desarrollando algunos conceptos del formalismo cuántico-, y luego se aborda el algoritmo de Grover el cual explota al máximo el principio de superposición. Finalmente se realiza una simulación clásica de dicho algoritmo, y los resultados obtenidos se comparan con otros algoritmos clásicos como el método de búsqueda lineal y búsqueda binaria. Se obtiene como resultado un %95 de mayor efectividad en tiempos -a la hora de resolver la misma búsqueda- logrando poner de manifiesto las ventajas potenciales de la computación cuántica

Quantum computation beyond the circuit model

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2008.Includes bibliographical references (p. 133-144).The quantum circuit model is the most widely used model of quantum computation. It provides both a framework for formulating quantum algorithms and an architecture for the physical construction of quantum computers. However, several other models of quantum computation exist which provide useful alternative frameworks for both discovering new quantum algorithms and devising new physical implementations of quantum computers. In this thesis, I first present necessary background material for a general physics audience and discuss existing models of quantum computation. Then, I present three new results relating to various models of quantum computation: a scheme for improving the intrinsic fault tolerance of adiabatic quantum computers using quantum error detecting codes, a proof that a certain problem of estimating Jones polynomials is complete for the one clean qubit complexity class, and a generalization of perturbative gadgets which allows k-body interactions to be directly simulated using 2-body interactions. Lastly, I discuss general principles regarding quantum computation that I learned in the course of my research, and using these principles I propose directions for future research.by Stephen Paul Jordan.Ph.D

Interpreting quantum nonlocality as platonic information

The "hidden variables" or "guiding equation" explanation for the measurement of quantum nonlocality (entanglement) effects can be interpreted as instantiation of Platonic information. Because these Bohm-deBroglie principles are already external to the material objects that they theoretically affect, interpreting them as Platonic is feasible. Taking an approach partially suggested by Quantum Information Theory which views quantum phenomena as sometimes observable-measurable information, this thesis defines hidden variables/guiding equation as information. This approach enables us to bridge the divide between the abstract Platonic realm and the physical world. The unobservable quantum wavefunction collapse is interpreted as Platonic instantiation. At each interaction, the wave function for a quantum system collapses. Instantly, Platonic information is instantiated in the system

Quantum control in the presence of relaxation

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2002.Includes bibliographical references (leaves 77-80).For certain problems quantum resources can exponentially increase computing power, but these quantum resources are very fragile in practice. When a quantum system interacts with an external environment, it undergoes decoherence - the loss of quantum correlation - and relaxation - the loss of energy - and eventually all of the quantum information is lost. Here we show a general principle of using unitary operators to suppress relaxation processes. Unitary operations do not cool a quantum system and seem an unlikely candidate for preventing irreversible thermodynamic heating processes, but surprisingly most decoherence processes can be corrected or ameliorated using open loop control with unitary controllers. We examine the different mechanisms of decoherence and relaxation on simple spin systems and discuss when the modes can be corrected. We show experimentally the feasibility of our correction schemes using nuclear magnetic resonance. We also demonstrate control of the nuclear spins over long time scales. Finally, we discuss the applications of unitary correction to higher dimensional systems and the potential applications to quantum information processing.by Benjamin Harris Recht.S.M

Light Matter Interaction in Single Molecule Magnets

This dissertation includes a series of experimental realizations which focus on studying the coupling between photons and single-molecule magnets (SMMs) in both the weak and strong coupling regimes. In the weak coupling regime, the aim is to achieve coherent control over the time evolution of the spin of SMMs while applying rapid microwave pulses at sub-Kelvin temperatures, where polarization of the spin bath may be achieved without large magnetic fields, allowing the suppression of dipolar dephasing. The continuing results of this experiment will be to provide a window into fundamental sources of decoherence in single-crystal SMMs in an energy range not thoroughly investigated. We expect that these conditions would allow us to study the quantum dynamics of the spins as governed by the intrinsic molecular magnetic anisotropy, which should give rise to non-well-defined Rabi oscillations of the spin state, including metastable precessional spin states. In the strong coupling regime, high quality factor superconducting CPW resonators have been designed and fabricated to investigate the vacuum Rabi splitting between a photon and the SMM spin. The proposed setup will permit measurements of coherent collective coupling between molecular spins and a low number of photons, ideally down to a single photon. This experiment may ultimately provide the opportunity for reaching the strong coupling regime with a single spin. Finally, this thesis also documents a research study into the impact of service-learning methodology on students\u27 depth of learning and critical thinking skills during a novel nanoscale science and technology course offered in the UCF Physics Dept. The overall learning of students was assessed and results clearly showed improvement in both multiple choice pre/post-tests and critical reflection papers. We associate this improvement at least partially to the service-learning experience

Processes and diagrams: an integrated and multidisciplinary approach for the education of quantum information science

The background to this thesis is the παιδέια , the education. To educate is a dialecti- cal process that moves from an abstract line of thought, through scientifically designed techniques, into concrete action; and vice versa. We believe that educating today means enabling teachers first and their students second, to be able to read and interpret the complexity of phenomena, to teach them a model for observing this complexity, describing it, analyzing it and, finally, making it their own. In this thesis, we attempt to make sense of these needs by describing an integrated and multidisciplinary pathway, whose diagram- matic language pushes towards the search for a universal approach to science. An initial educational contribution is thus made to the understanding of the dialectic between disciplines: theoretical physics, experimental physics, computer science, mathe- matics and mathematical logic are presented in their mutual influence, in an attempt to clarify the informational viewpoint on modern physics. The search for this dialectic for educational purposes is, in our opinion, the most significant contribution of the present work. To address this issue, we sought to build a community of practice on the topics of the second quantum revolution. Guided by the Model of Educational Reconstruction (MER), we built a first course for teacher professional development that would enable teachers to be introduced to quantum computation and quantum communication. The emergence and development of quantum technologies provides the impetus for a deep conceptual change: “a paradigm shift from quantum theory as a theory of microscopic matter to quantum theory as a framework for technological applications and information processing”. This shift is supported, theoretically, by the informational interpretation of the postulates of quantum mechanics: preparation, transformation and measurement are reinterpreted com- putationally as the encoding, processing and decoding of information; and vice versa. In this interpretation, what changes between classical and quantum theory? From a logical point of view, the transition from bit to qubit, from a physical point of view, the laws of composition of systems. We therefore present monoidal categories as a natural theoretical framework for the description of physical systems and processes for quantum and non- quantum computation and communication, demonstrating how this language is suitable for an integrated and multidisciplinary approach. The cultural impact of the proposal, the fruitful interaction between researchers in physics education and those in the area of theoretical research, and the passion of some teachers made it possible to start a collaboration to build an educational sequence for students. The result of this collaboration is a teaching leaning sequence on quantum technologies for students, led by the MER and based on inquiry-based learning and the modelling- based teaching. Supported by these methodological frameworks, we produced lessons and worksheets all along the way that had the dual task of supporting teachers’ work and students’ learning. They also made it possible to experimentally verify the positive and critical effects of the proposal. The instructional materials constructed, the data analysis and the constant monitoring with the teachers involved, determined the development of a second course for teacher professional development, inspired by the first, based entirely on research. We hope that this attempt at integrated and multidisciplinary approach for the education of quantum information science, based on the concept of compositionality and the diagrammatic model, can be increased and provide inspiration for future educational paths in other disciplines as well