Hi all,
tomorrow we'll hear from Nuriya Nurgalieva on her master's thesis. The title and abstract follow. We should also discuss whether Monday at 4pm will be a convenient meeting time for everyone this semester.
Best,
-joe
Title: Quantum reference frames for experiments where observers can be measured
Abstract: Frauchiger and Renner recently proposed an expansion of Wigner’s friend experiment to prove that single-world interpretations of quantum theory cannot be self-consistent. Experimenters are modeled as agents who use quantum theory, and additionally can themselves be measured as physical systems. However, Frauchiger and Renner’s description of the experiment implicitly assumes that all agents have access to perfect, classical reference frames. In doing so it imposes artificial classicality on a setting that tries to model only quantum evolutions, and risks missing out on subtleties that could explain the paradox. We model each lab as a system which consists of a spin, a reference frame and an agent’s memory, evolving under a unitary. Concretely, we investigate whether different agents refer to the same degrees of freedom and quantum subsystems when they talk about the outcome of a measurement. Our results show that in the setting with the finite reference frames agents are not able to make deterministic predictions.