Fabio Costa - "Quantum Causal Structures"

by Dr Fabio Costa (Nordita)

Wednesday 22 Feb 2023, 16:15 → 18:15 Europe/Stockholm

Albano 3: 6228 - Mega (22 seats) (Albano Building 3)

Quantum Theory requires a background causal structure for its formulation, with temporal and spatial correlations treated in a very asymmetric way. However, in a theory combining Quantum Theory with General Relativity, spacetime might lose its classical properties, motivating a more general formulation where causal relations are not set a priori. A further motivation comes from distributed networks, where the causal order of events might not be known a priori. In this talk, I will give an introduction to quantum causal structures, a framework that posits the local validity of quantum mechanics but allows for aribtirary, possibly indefinite causal relations between events. Indefinite causal relations can be realised in thought experiments involving superpositions of spacetime metrics, but also describe laboratory experiments with events delocalised in time, opening the way to novel resources for computation and communication. Finally, the same formalism provides a natural framework to describe non-Markovian quantum processes, resolving an open problem in the study of open quantum systems.