Nonclassical correlations from randomly chosen local measurements

Abstract

We show that correlations inconsistent with any locally causal description can be a generic feature of measurements on entangled quantum states. Specifically, spatially-separated parties who perform local measurements on a maximally-entangled state using randomly chosen measurement bases can, with significant probability, generate nonclassical correlations that violate a Bell inequality. For n parties using a Greenberger-Horne-Zeilinger state, this probability of violation rapidly tends to unity as the number of parties increases. We also show that, even with both a randomly chosen two-qubit pure state and randomly chosen measurement bases, a violation can be found about 10% of the time. Amongst other applications, our work provides a feasible alternative for the demonstration of Bell inequality violation without a shared reference frame.

v3 (published version) 7 pages, 4 figures, 1 table, results considerably strengthened, references updated; v2 4 pages, 3 figures, margins tightened, references updated, minor errors fixed, Fig1 and Fig 2 replaced; v1 4+ pages, 3 figures