Year: 2026
Type: dissertation
Abstract: This thesis studies fixed point non-uniqueness in Deutsch's model of time travel along a closed timelike curve (CTC), primarily focusing upon the bootstrap problem in the two-qubit setting. This thesis focuses on how the under-determination stemming from the bootstrap problem is structured, how prevalent it is, and whether it can be resolved by a physical mechanism, rather than an externally imposed rule. These questions are primarily addressed in the restricted setting of a two-qubit system, where mathematical criteria for uniqueness and non-uniqueness are developed analytically. From these criteria, it is shown that in the two-qubit setting, the non-unique sector is confined to a thin exceptional subset of the full parameter space. The thesis then turns to examine noise as a physical mechanism for resolving under-determination, and analytically characterizes the types of channels that will universally select a unique fixed point when composed with single-qubit D-CTC systems.
Author: Hazel Gifford
Institution: Brock University
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7208801186