Research ArticleQUANTUM PHYSICS

Experimental test of nonlocal causality

Science Advances  10 Aug 2016:
Vol. 2, no. 8, e1600162
DOI: 10.1126/sciadv.1600162

You are currently viewing the abstract.

View Full Text

Abstract

Explaining observations in terms of causes and effects is central to empirical science. However, correlations between entangled quantum particles seem to defy such an explanation. This implies that some of the fundamental assumptions of causal explanations have to give way. We consider a relaxation of one of these assumptions, Bell’s local causality, by allowing outcome dependence: a direct causal influence between the outcomes of measurements of remote parties. We use interventional data from a photonic experiment to bound the strength of this causal influence in a two-party Bell scenario, and observational data from a Bell-type inequality test for the considered models. Our results demonstrate the incompatibility of quantum mechanics with a broad class of nonlocal causal models, which includes Bell-local models as a special case. Recovering a classical causal picture of quantum correlations thus requires an even more radical modification of our classical notion of cause and effect.

Keywords
  • Quantum foundations
  • causality
  • Bell inequality
  • causal models
  • quantum mechanics
  • local causality
  • local realism
  • nonlocal causality
  • nonlocality

This is an open-access article distributed under the terms of the Creative Commons Attribution-NonCommercial license, which permits use, distribution, and reproduction in any medium, so long as the resultant use is not for commercial advantage and provided the original work is properly cited.

View Full Text

More Like This