Quantum theory can be formulated using a small number of mathematical postulates. These postulates describe how quantum systems interact and evolve as well as describing measurements and probabilities of measurement outcomes. The measurement postulates are logically independent from the other postulates, which are dynamical and compositional in nature. In this thesis we study all theories which have the same dynamical and compositional postulates as quantum theory but different measurement postulates. In the first part we introduce the necessary tools for this task: the operational approach to physical theories (general probabilistic theories) and the representation theory of the unitary group. Following this we introduce a framework which is used to describe theories with modified measurement postulates and we classify all possible alternative measurement postulates using representation theory. We then study informational properties of single systems described by these theories and compare them to quantum systems. Finally we study properties of bi-partite systems in these theories. We show that all bi-partite systems in these theories violate two properties which are met by quantum systems: purification and local tomography.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:763245 |
| Date | January 2018 |
| Creators | Galley, Thomas |
| Publisher | University College London (University of London) |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://discovery.ucl.ac.uk/10059145/ |
Page generated in 0.0014 seconds