Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 17 of 17 for “"Quantum walk"”.
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Verschränkungsstrukturen in multidimensionalen diskreten Quantum Walk Modellen
… Startzustände auf multidimensionale diskrete Quantum Walk Modelle untersucht. Durch die sich ergebenden Ortskorrelationen, ist es möglich die Struktur der Verschränkung zu analysieren und die Verschräankung selbst zu messen. Dazu werden für eindimensionale Multicoin Modelle und für …
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Spatial search by quantum walk with a randomized local start state
In this thesis, we present a quantum walk algorithm for spatial search of a periodic lattice. Our algorithm is a variation of the Childs and Goldstone algorithm for spatial search, but begins in a randomly selected local initial state rather than a uniformly delocalized one. We analytically …
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Application of quantum walks on graph structures to quantum computing
Quantum computation is a new computational paradigm which can provide fundamentally faster computation than in the classical regime. This is dependent on finding efficient quantum algorithms for problems of practical interest. One of the most successful tools in developing new quantum algorithms is …
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Implementing Quantum Gates With Length-3 Dynamic Graphs
The continuous-time quantum walk is a quantum version of a random walk that evolves by Schrodinger's equation. With the Hamiltonian equal to the adjacency matrix of a sequence of graphs, called a dynamic graph, continuous-time quantum walks have been shown to implement quantum gates, including the …
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Absorption phenomena in quantum walks
The quantum walk is a unitary analogue to the discrete random walk, and its properties have been increasingly studied since the turn of the millennium. In comparison with the classical random walk, the quantum walk exhibits linear spreading and initial condition dependent asymmetries. As noted …
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Evaluation of boolean formulas with restricted inputs
… thesis, I will investigate the running time of quantum algorithms for evaluating boolean functions when the input is promised to satisfy certain conditions. The two quantum algorithms considered in this paper are the quantum walk algorithm for NAND trees given by Farhi and Gutmann [2], and an …
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Quantum information processing in continuous time
Quantum mechanical computers can solve certain problems asymptotically faster than any classical computing device. Several fast quantum algorithms are known, but the nature of quantum speedup is not well understood, and inventing new quantum algorithms seems to be difficult. In this thesis, we …
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Sampling Using Controlled Quantum Walks
We give a new quantum algorithm to sample from probability distributions over graph vertices quadratically faster than the optimal classical algorithm, which uses random walks with stopping rules. Efficient sampling is an important computational task used in simulations based on stochastic …
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Topics in quantum information theory and quantum many-body physics
… two results relating to the intersection between quantum information theory and quantum many-body physics. The first pertains to quantum algorithms, where few computational problems are believed to exhibit exponential separation between quantum and classical performance. For those that are, …
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Novel Aspects of Localization, Delocalization, and Anomalous Transport in One-dimensional Systems
… we move to another novel system, a disordered quantum walk (QW) model. We demonstrate that our QW model possesses the physics of off-diagonal disorder, and propose an experimental realization of the delocalized off-diagonal disordered state using the adiabatic theorem. Lastly, we study an …
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Quantum Algorithms For String Problems
We design near-optimal quantum query algorithms for two important text processing problems: Longest Common Substring and Lexicographically Minimal String Rotation. Specifically, we show that: - Longest Common Substring can be solved by a quantum algorithm in Õ(n²⸍³) time, improving upon the …
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Machine-learning-assisted state and gate engineering for quantum technologies
… we discuss applications of machine learning to quantum information science. The interface between these two fields has been the subject of much research, recently, driven by the many successes of machine learning for diverse pattern recognition tasks. The work reported in this Thesis addresses …
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Quasicrystalline optical lattices for ultracold atoms
… of the most successful tools in the large-scale quantum simulation of condensed-matter problems. This study presents the first experimental realisation of a two-dimensional quasicrystalline potential for ultracold atoms, based on an eightfold symmetric optical lattice. It is aimed at bringing …
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The cold atom toolbox in momentum space
"The many weird properties of quantum mechanics at the very small scale have led to surprising and useful discoveries that manifest at the macroscopic level, like the quantum Hall effect and high temperature superconductivity. Yet trying to understand the origin of correlated behavior from …
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Phases and non-equilibrium dynamics of ultracold bosons in an optical quasicrystal
… quasicrystalline lattices, studied by means of quantum simulation using ultracold 39K atoms loaded to an eight-fold rotationally symmetric optical quasicrystal. Quasicrystalline and quasiperiodic systems, thanks to their long-range order and lack of periodicity, exhibit a wealth of interesting …
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Some Aspects of Fluctuation Driven Phenomena
… such as thermal noise, stochasticity, or even quantum fluctuations. The importance of understanding these phenomena lies in their ubiquity in natural systems, from the formation of patterns in biological systems, to the behavior of phase transitions and universality classes, to quantum …
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CHARACTERIZATION AND ENGINEERING OF QUANTUM SYSTEMS
… the exceptional results and developments that quantum mechanics, in combination with information theory, has developed in recent decades. This thesis is part of this line of research, with the scope of providing new results regarding quantum sensing and quantum control. Firstly, the need for …