title: Multiple Observers Can Share the Nonlocality of Half of an Entangled Pair by Using Optimal Weak Measurements.
abstract: We investigate the trade-off between information gain and disturbance for von Neumann measurements on spin-1/2 particles, and derive the measurement pointer state that saturates this trade-off, which turns out to be highly unusual. We apply this result to the question of whether the nonlocality of a single particle from an entangled pair can be shared among multiple observers that act sequentially and independently of each other, and show that an arbitrarily long sequence of such observers can all violate the Clauser-Horne-Shimony-Holt-Bell inequality.
authors.affiliation: H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
authors.forename: Ralph
authors.initials: R
authors.lastname: Silva
authors.affiliation: Group of Applied Physics, University of Geneva, CH-1211 Geneva 4, Switzerland.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Gisin
authors.affiliation: H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
authors.forename: Yelena
authors.initials: Y
authors.lastname: Guryanova
authors.affiliation: H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom.
authors.forename: Sandu
authors.initials: S
authors.lastname: Popescu