An introduction to causal order, Viktoria Kabel (Universität Wien and IQOQI Wien)

Understanding causality in the context of quantum gravity is a challenging task. This talk will explore the topic from the perspective of quantum foundations and quantum information. There, the study of indefinite causal order (ICO), concerned with processes that cannot be described in terms of even probabilistic classical causal structures, is a vibrant area of research. The first part of the talk will offer a brief review of a general framework for ICO – the process matrix formalism – and several examples of processes exhibiting ICO. In the second part, I will turn to the connection with spacetime physics. There, I will discuss how to understand ICO in the context of superpositions of spacetimes by extending common general relativistic notions to such scenarios, and raise some open problems for a more general understanding of ICO in the context of quantum spacetime.