Eleftherios Tselentis: The Möbius game and other Bell test for relativity - RQI Circuit Vienna 2023

Title: The Möbius game and other Bell test for relativity
Abstract: We derive multiparty games that, if the winning chance exceeds a certain limit, prove the incompatibility of the parties’ causal relations with any partial order. This, in turn, means that the parties exert a back-action on the causal relations; the causal relations are dynamical. The games turn out to be representable by directed graphs, for instance by an orientation of the Möbius ladder. We discuss these games as device-independent tests of spacetime’s dynamical nature in general relativity. To do so, we design a relativistic setting where, in the Minkowski spacetime, the winning chance is bound to the limits. In contrast, we find otherwise tame processes with classical control of causal order that win the games deterministically. These suggest a violation of the bounds in gravitational implementations. We obtain these games by uncovering a “pairwise central symmetry” of the correlations in question and by reducing the problem to the acyclic subgraph problem, a known NP-complete linear combinatorial optimization problem. In addition, we derive multiparty games in a scenario where the polytope dimension grows only linearly in the number of parties. Here, exceeding the limits not only proves the dynamical nature of the causal relations, but also that the correlations are incompatible with any global causal order.
Talk delivered at IQOQI Vienna on November 10th 2023.
Broadcast and editing by Rick Perche.