In this thesis I address two different topics in quantum theory. The first one is the long discussed Schrodinger's cat problem, and the issues related to having a macroscopic superposition state. I show that the quantum theory provides full explanation to the problem. In the second part, I discuss the time measurement related issues in quantum mechanics. Since there does not exist any time operator in quantum mechanics generally, time is not directly measurable. Therefore we should devise other methods to register time. We study different time-energy relations and will find that accurate clocks have high energy uncertainties. If we use accurate clocks in quantum systems to observe their time evolutions, their high energy uncertainties interfere with system's normal evolution and slows it down. I also provide a formal proof to a previously suggested limiting accuracy relation on the measurements of the time-of-arrival experiments.

Cohesive energies, bulk moduli, and equilibrium lattice constants have been calculated for the 5d transition atoms (Hf, Ta, W, Re, Os, Ir and Pt) in face–centred cubic crystal lattices. We have used the ab initio pseudopotential method for the total energy calculations within the local density approximation. Two calculations have been performed for each element, one using only the s, p and d angular momentum components and another including the s, p and d components as well as the unoccupied 5f orbital in the ionic pseudopotentials. The pseudo–wave functions and charge densities of the valence electrons have been represented by a basis of plane waves. For the 5d metals the changes in the electronic structure of the solid are small and they produce small changes in the bulk properties. / Thesis (M.Sc.) - University of KwaZulu-Natal, Pietermaritzburg, 2008.

One key goal of Physics Education Research is providing research-based instructional techniques and tools to help assess the complex learning goals associated with a mature understanding of physics. Characterizing faculty expectations is important to produce a comprehensive understanding of knowledge students should acquire before and during a quantum mechanics course (QMC). Semi-structured interviews have been conducted with faculty members and students entering a QMC in the Physics Program at a Large Public Research University (LPRU) in the Southeast. The interviews examine perspectives of different evaluation techniques, ideal preparation, course content, and expected conceptual models of students. A post-course survey was offered to the students that took the QMC in the Fall of 2012 and to those who completed the course in the past three years. The survey addressed similar questions on evaluation, course content, and preparation. Using Classical Content Analysis and Key-Words-In-Context coding methods, contradictions and similarities within and between faculty and student populations are presented. These results are presented in an effort to highlight predictors for success in the QMC, identify “common-core” perceptions, and strengthen course evaluation. In all data, findings suggest that student perceptions shift towards those of faculty over the course of the QMC. Evaluation data indicate that on average the faculty members, like students, are open to a varied array of evaluation techniques, if it is within the goals of the course and does not interfere with other faculty responsibilities. In perceptions of preparation and course content, faculty have a uniform perspective of what should be prerequisite, and the student survey data strongly recommend that the second semester of Linear Algebra offered at the LPRU will help with the mathematical complexities of the QMC. Through triangulation of qualitative and quantitative results contradictions of preparation and content are exhibited through multiple media for the use course content such as the Hamiltonian.

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This thesis is a contribution to the debate on the implications of quantum information theory for the foundational problems of quantum mechanics. In Part I an attempt is made to shed some light on the nature of information and quantum information theory. It is emphasized that the everyday notion of information is to be firmly distinguished from the technical notions arising in information theory; however it is maintained that in both settings ‘information’ functions as an abstract noun, hence does not refer to a particular or substance. The popular claim ‘Information is Physical’ is assessed and it is argued that this proposition faces a destructive dilemma. Accordingly, the slogan may not be understood as an ontological claim, but at best, as a methodological one. A novel argument is provided against Dretske’s (1981) attempt to base a semantic notion of information on ideas from information theory. The function of various measures of information content for quantum systems is explored and the applicability of the Shannon information in the quantum context maintained against the challenge of Brukner and Zeilinger (2001). The phenomenon of quantum teleportation is then explored as a case study serving to emphasize the value of recognising the logical status of ‘information’ as an abstract noun: it is argued that the conceptual puzzles often associated with this phenomenon result from the familiar error of hypostatizing an abstract noun. The approach of Deutsch and Hayden (2000) to the questions of locality and information flow in entangled quantum systems is assessed. It is suggested that the approach suffers from an equivocation between a conservative and an ontological reading; and the differing implications of each is examined. Some results are presented on the characterization of entanglement in the Deutsch-Hayden formalism. Part I closes with a discussion of some philosophical aspects of quantum computation. In particular, it is argued against Deutsch that the Church-Turing hypothesis is not underwritten by a physical principle, the Turing Principle. Some general morals are drawn concerning the nature of quantum information theory. In Part II, attention turns to the question of the implications of quantum information theory for our understanding of the meaning of the quantum formalism. Following some preliminary remarks, two particular information-theoretic approaches to the foundations of quantum mechanics are assessed in detail. It is argued that Zeilinger’s (1999) Foundational Principle is unsuccessful as a foundational principle for quantum mechanics. The information-theoretic characterization theorem of Clifton, Bub and Halvorson (2003) is assessed more favourably, but the generality of the approach is questioned and it is argued that the implications of the theorem for the traditional foundational problems in quantum mechanics remains obscure.

Thesis (M.S.); Submitted to the Univ. of Texas A and M, College Station, TX (US); 4 Oct 2004. / Published through the Information Bridge: DOE Scientific and Technical Information. "UCRL-TH-208163" Schilling, O; Mueschke, N J. 10/04/2004. Report is also available in paper and microfiche from NTIS.

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (p. [100]-109).

Thesis--Rijksuniversiteit te Utrecht. / Vita. Summary also in Dutch. Includes bibliographical references. Also issued in print.

Thesis--Rijksuniversiteit te Utrecht. / Vita. Summary also in Dutch. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis (Ph. D.)--Carleton University, 1992. / Also available in electronic format on the Internet.