Nonclassical correlations from randomly chosen local measurements

TL;DR

This paper demonstrates that randomly chosen local measurements on entangled quantum states often produce nonclassical correlations violating Bell inequalities, with probabilities increasing with the number of parties, offering practical ways to observe quantum nonlocality.

Contribution

It shows that nonclassical correlations can emerge from random measurements on entangled states, providing a new, feasible approach to demonstrate Bell violations without shared reference frames.

Findings

High probability of Bell violation with many parties using GHZ states

Approximately 10% chance of violation with random two-qubit states

Bell violations can be observed without shared reference frames

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.