Postquantum steering

Understand

The discovery of postquantum nonlocality, i.e., the existence of nonlocal correlations that are stronger than any quantum correlations but nevertheless consistent with the no-signaling principle, has deepened our understanding of the foundations of quantum theory.

• In this work, we investigate whether the phenomenon of Einstein-Podolsky-Rosen steering, a different form of quantum nonlocality, can also be generalized beyond quantum theory.
• While postquantum steering does not exist in the bipartite case, we prove its existence in the case of three observers.
• Importantly, we show that postquantum steering is a genuinely new phenomenon, fundamentally different from postquantum nonlocality.