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 20 of 21 for “"Quantum chaos"”.
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Quantum chaos and phase transitions
Quantum materials permeate the modern world - these are systems that exhibit quantum mechanical properties, like topological phases and superconductivity, at macroscopic scales. The principles governing quantum materials include entanglement and coherence -phenomena which are fundamentally quantum …
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The quantum Fourier transform and quantum chaos
In this thesis I study control of quantum systems while implementing complex quantum operations. Through experimental implementations of such operations, I test the accuracy of control and provide methods for identifying the type and strength of experimental errors. The centerpiece of this work is …
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Correlated trajectories in semiclassical approaches to quantum chaos
… universal statistics of classically chaotic quantum systems. First we consider systems that depend on an external parameter that does not change the symmetry of the system. We study correlations between the spectra at different values of the parameter, a scaled distance $x$ apart, via the …
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Random matrices, quantum chaos and irreversible classical dynamics
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1996.
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Rydberg atoms in strong fields : a testing ground for quantum chaos
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1995.
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Experimental and theoretical aspects of quantum chaos in Rydberg atoms in strong fields
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1996.
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Chaos and Scrambling in Quantum Small Worlds
… thesis, we introduce a novel class of many-body quantum system, which we term ‘quantum small worlds'. These are strongly-interacting systems that interpolate between completely ordered (nearest-neighbour, next-to-nearest-neighbour etc.) and completely random interactions. They are systems of …
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The Quantum Kicked Rotor
The quantum kicked rotor has served as a model for testing the ideas of quantum chaos since the field's inception. In this thesis we present an overview of the kicked rotor, both from a semiclassical standpoint as well as from a purely quantum standpoint. At the heart of our kicked rotor model is a …
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Quantum-classical correspondence in response theory
… analysis of correspondence between classical and quantum dynamics is studied in the context of response theory. Thesis discusses the mathematical origin of time-divergence of classical response functions and explains the failure of classical dynamic perturbation theory. The method of phase space …
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Chaos and Localisation
This thesis investigates quantum transport in the energy space of two paradigm systems of quantum chaos theory. These are highly excited hydrogen atoms subject to a microwave field, and kicked atoms which mimic the delta-kicked rotor model. Both of these systems show a complex dynamical evolution …
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Quantum Algorithms and Non-Equilibrium Dynamics in Many-Body Systems
Understanding the physical features of quantum many-body systems is a challenging endeavor spanning across multiple branches of physics. In this thesis, we explore the properties of one- and two-dimensional quantum systems in the context of quantum algorithms and non-equilibrium dynamics. In the …
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Chaos and Momentum Diffusion of the Classical and Quantum Kicked Rotor
The de Broglie-Bohm (BB) approach to quantum mechanics gives trajectories similar to classical trajectories except that they are also determined by a quantum potential. The quantum potential is a "fictitious potential" in the sense that it is part of the quantum kinetic energy. We use quantum …
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Aspects of quantum states of matter
… two aspects of the spectra of low-dimensional quantum systems with potential relevance for modern condensed matter and holography. We begin with a study of two-dimensional systems in magnetic fields whose spectra exhibit Landau level structure. We then study disordered quantum field theories …
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Eigenfunctions in chaotic quantum systems
The structure of wavefunctions of quantum systems strongly depends on the underlying classical dynamics. In this text a selection of articles on eigenfunctions in systems with fully chaotic dynamics and systems with a mixed phase space is summarized. Of particular interest are statistical …
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Aspects of Eigenstate Thermalization
For chaotic quantum many-body systems, the eigenstate thermalization hypothesis (ETH) posits that energy eigenstates contain the properties of equilibrium ensembles. Many subsequent devel- opments have demonstrated the centrality of random matrix theory and free probability to the ETH. This thesis …
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Dynamical signatures of instantons: insights from path-integral studies
In thermal quantum systems, the quantum effects arising from the Boltzmann distribution, that governs some of its statistical properties, can be accurately quantified using imaginary-time Feynman path integrals. While traditionally used as a method to account for static quantum effects of atomic …
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Fractal Dimensions in Classical and Quantum Mechanical Open Chaotic Systems
… account in that range. Lastly, we show that in quantum analogues of chaotic maps with a partial leak, a related effective dimension can be used to explain the numerically observed deviation from the predictions provided by the fractal Weyl law for systems with fully absorbing leaks. Here, we …
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Dynamical Tunneling in Systems with a Mixed Phase Space
… is one of the most prominent features of quantum mechanics. While the tunneling process in one-dimensional integrable systems is well understood, its quantitative prediction for systems with mixed phase space is a long-standing open challenge. In such systems regions of regular and chaotic …
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