http://hdl.handle.net/1721.1/7695 Tue, 21 May 2013 02:51:25 GMT 2013-05-21T02:51:25Z http://hdl.handle.net/1721.1/77867 The shift of energy levels due to radiative coupling French, James Bruce Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1948.; Vita.; Includes bibliographical references (leaf 73). Thu, 01 Jan 1948 05:00:00 GMT http://hdl.handle.net/1721.1/77867 1948-01-01T05:00:00Z http://hdl.handle.net/1721.1/77753 Techniques for laser interferometer gravitational wave detectors Fritschel, Peter Kurt Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1992.; Includes bibliographical references (leaves 100-102). Wed, 01 Jan 1992 05:00:00 GMT http://hdl.handle.net/1721.1/77753 1992-01-01T05:00:00Z http://hdl.handle.net/1721.1/77542 Quantum gates, sensors, and systems with trapped ions Wang, Shannon Xuanyue Quantum information science promises a host of new and useful applications in communication, simulation, and computational algorithms. Trapped atomic ions are one of the leading physical systems with potential to implement a large-scale quantum information system, but many challenges still remain. This thesis describes some experimental approaches to address several such challenges broadly organized under three themes: gates, sensors, and systems. Quantum logic gates are the fundamental building blocks for quantum algorithms. Although they have been demonstrated with trapped ions previously, scalability requires miniaturizing ion traps by using a surface-electrode geometry. Using a single ion in a surface-electrode trap, we perform a two-qubit entangling gate and fully characterize it via quantum process tomography, as an initial validation of surface-electrode ion traps for quantum information processing. Good logic gates are often good sensors for fast fluctuations and energy changes in their environment. Trapped ions are sensitive to fluctuating and static charges, leading to motional state decoherence (heating) and instabilities, problems exacerbated by the surface-electrode geometry. We investigate the material dependence of heating, specifically with aluminum and superconducting traps, to elucidate the physical origin of these fluctuating charges. Static charging is hypothesized to be caused by the trapping and cooling lasers due to the photoelectric effect. We perform systematic experiments with aluminum, gold, and copper traps with lasers at various wavelengths to validate this hypothesis. Realizing quantum processors at the system level requires models and tools for predicting system performance, demonstration of good classical and quantum control, and techniques for integrating different quantum systems. We develop a modeling system for trapped ion quantum computing experiments and simulate the effect of physical and technical noise sources on practical realizations of quantum algorithms in a trapped ion system. We experimentally demonstrate several such algorithms, including the quantum Fourier transform, order-finding, and Shor's algorithm on up to 5 ions. These experiments highlight several unique advantages of ion trap systems and help identify needs for further development. Finally, we explore the integration of ion traps with optical elements including mirrors and photon detectors as key elements in creating future hybrid quantum systems. Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.; Cataloged from PDF version of thesis.; Includes bibliographical references (p. 203-218). Sun, 01 Jan 2012 05:00:00 GMT http://hdl.handle.net/1721.1/77542 2012-01-01T05:00:00Z http://hdl.handle.net/1721.1/77506 Studies of strong-field gravity : testing the black hole hypothesis and investigating spin-curvature coupling Vigeland, Sarah Jane Observations of gravitational systems agree well with the predictions of general relativity (GR); however, to date we have only tested gravity in the weak-field limit. In the next few years, observational advances may make it possible for us to observe motion in the strong field for the first time. This thesis is concerned with two probes of strong-field gravity: whether the spacetime of a black hole has the structure predicted by GR, and the effect of spin-curvature coupling on orbital motion in the large mass-ratio limit. The first two-thirds of this thesis develop a formalism for determining whether a candidate black hole is described by the Kerr metric, as predicted by GR for all black holes in vacuum. In the first chapter, we describe how to construct a "bumpy black hole," an object whose spacetime is almost, but not quite, the Kerr metric. We define perturbations to the mass and spin moments and relate the changes in the moments to changes in the orbital frequencies using canonical perturbation theory. In the second chapter, we extend the bumpy black hole formalism to include black holes in non-GR theories of gravity, which leads to additional functional degrees of freedom. The final chapter investigates the effects of spin-curvature coupling. For a small body with spin moving around a massive black hole, the spin of the small body couples to the background curvature, and its trajectory deviates from a geodesic. To date, there has been relatively little work that considers this effect except in the special cases of aligned spins and circular, equatorial orbits. We compute the perturbation to the trajectory and the spin precession due to spin-curvature coupling for generic orbits of Kerr and arbitrary initial spin orientations. Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 2012.; This 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 (p. 151-159). Sun, 01 Jan 2012 05:00:00 GMT http://hdl.handle.net/1721.1/77506 2012-01-01T05:00:00Z