Hello,

Tomorrow 20/02/2025, I will give an informal seminar on

"Finitely many worlds with finite information flow and Bell theorem"

Abstract:

The Copenhagen interpretation of quantum theory does not provide a measurement-independent description of physical processes. Two competing approaches to this issue are single-world ontological theories and Everett many-worlds theory. The former addresses the measurement problem by introducing auxiliary random variables that specify, in particular, the actual values of macroscopic observables. Such models may be ψ-epistemic, meaning the quantum state is not part of the ontology. However, all the ontological models break the principle of locality, as demonstrated by Bell’s theorem. The latter approach, which is deterministic and ψ-ontic, offers the advantage of evading Bell’s theorem by delaying the buildup of the correlations until the parties compare their outcomes at a meeting point. Because of determinism and the ontic nature of the quantum state, the number of parallel worlds and the information flow towards the meeting point turn out to be infinite. By integrating the strengths of the two approaches, we introduce a simple ψ-epistemic, many-worlds, local model of projective measurements on two spatially separate maximally entangled qubits. Because of its randomness, the model requires only two branches and a finite information flow – just one bit per measurement is communicated to the meeting point. We explore how this hybrid approach addresses key challenges of each individual framework.