RT Journal Article
T1 Observers of quantum systems cannot agree to disagree
A1 Contreras Tejada, Patricia
A1 Scarpa, Giannicola
A1 Kubicki, Aleksander M.
A1 Brandenburger, Adam
A1 La Mura, Pierfrancesco
AB Is the world quantum? An active research line in quantum foundations is devoted to exploring what constraints can rule out the postquantum theories that are consistent with experimentally observed results. We explore this question in the context of epistemics, and ask whether agreement between observers can serve as a physical principle that must hold for any theory of the world. Aumann’s seminal Agreement Theorem states that two observers (of classical systems) cannot agree to disagree. We propose an extension of this theorem to no-signaling settings. In particular, we establish an Agreement Theorem for observers of quantum systems, while we construct examples of (postquantum) no-signaling boxes where observers can agree to disagree. The PR box is an extremal instance of this phenomenon. These results make it plausible that agreement between observers might be a physical principle, while they also establish links between the fields of epistemics and quantum information that seem worthy of further exploration.
PB Nature Research
SN 2041-1723
YR 2021
FD 2021-12-02
LK https://hdl.handle.net/20.500.14352/4983
UL https://hdl.handle.net/20.500.14352/4983
LA eng
NO Ministerio de Ciencia e Innovación (MICINN)
NO Comunidad de Madrid
DS Docta Complutense
RD 7 abr 2025