Quantum Theory

: Causality, Thermodynamics and Post-Selection

Abstract

This thesis explores the interplay between quantum theory, post selection, thermodynamics and causality. In the first chapter, we review some notation and concepts key to quantum information science. In chapter two, we will present work on channels, measurements and post-selection with an emphasis on the thermodynamics of such objects. In the third chapter, we will expand on what we mean when we say causality is classical in quantum theory. Chapter
four goes beyond quantum theory, to a fantasy quantum mechanics that can be simulated via post selection. We show that a local notion of no-backwards-in-time signalling is insufficient to ensure a global causal description of quantum theory. Finally, in chapter five, we will present the resource theory of post-selection.

Date of Award	12 May 2022
Original language	English
Awarding Institution	University of Bristol
Supervisor	A J Short (Supervisor)