title: Postquantum Steering.
abstract: 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 post-quantum 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. Our results provide new insight into the nonlocal correlations of multipartite quantum systems.
authors.affiliation: H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
authors.forename: Ana Belén
authors.initials: AB
authors.lastname: Sainz
authors.affiliation: Département de Physique Théorique, Université de Genève, 1211 Genève, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Brunner
authors.affiliation: ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, Castelldefels, 08860 Barcelona, Spain.
authors.forename: Daniel
authors.initials: D
authors.lastname: Cavalcanti
authors.affiliation: H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom.|ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, Castelldefels, 08860 Barcelona, Spain.
authors.forename: Paul
authors.initials: P
authors.lastname: Skrzypczyk
authors.affiliation: Département de Physique Théorique, Université de Genève, 1211 Genève, Switzerland.|Institute for Nuclear Research, Hungarian Academy of Sciences, P.O. Box 51, H-4001 Debrecen, Hungary.
authors.forename: Tamás
authors.initials: T
authors.lastname: Vértesi