Sandu Popescu (“poh-PESS-koo”) and Daniel Rohrlich (“roar-lick”) showed that theories in which relativistic causality and this property are axioms form a superset of quantum mechanics. Standard protocols in quantum information theory use operations that [emphasize] do not have this property along with classical communication. Realist theories that [emphasize] do not have this property are violated by the three-particle GHZ state. Theories with this property violate the upper bound of “two square root two” on the expression: “E of A, B” plus “E of A, B-prime” plus “E of A-prime, B” minus “E of A-prime, B-prime;” that expression is the CHSH inequality. Because quantum mechanics is causal and has this property, Einstein, Podolsky, and Rosen argued that the theory was incomplete. Hidden variable theories must have this property to be able to predict quantum results, as argued by John Bell. For 10 points, name this property of being influenced by distant systems. ■END■
ANSWER: nonlocality [prompt on entangled or entanglement or correlated or correlation; prompt on descriptions of having hidden variables until “Hidden variable theories” is read] (The second sentence refers to LOCC protocols.)
<Physics>
= Average correct buzz position