Quantum violations of Bell inequalities show that the physical world cannot simultaneously satisfy a set of seemingly natural assumptions, including locality, freedom of choice, and classical cause–and–effect relations. This fundamental feature of quantum mechanics, known as nonlocality, highlights a deep conflict with classical intuitions. Recent work has explored whether this conflict can be resolved by adopting broader notions of causality. In particular, extended Wigner’s friend scenarios suggest that quantum correlations remain incompatible with classical reasoning even within more general causal frameworks. In this seminar, I will introduce quantum nonlocality and its causal description, and discuss the conceptual challenges raised by Wigner’s friend. I will then present recent joint work between Griffith University and Sapienza University of Rome (Sciarrino’s group). We studied an instrumental causal network that allows communication between parties and show, both theoretically and experimentally using photonic systems, that quantum correlations still defy any model satisfying the principles of freedom of choice, the absoluteness of observed events, and generalized causal relations. These results point to an even stronger departure of quantum physics from classical worldviews.
Seminar at Quantum Lab: “Strong Quantum Nonclassicality Beyond Classical Causality” by Dr. Emanule Polino from Griffith University, Brisbane, Australia
