An experimental test of non-local realism

Author(s)

Simon Gröblacher, Tomasz Paterek, Rainer Kaltenbaek, Caslav Brukner, Marek Zukowski, Markus Aspelmeyer, Anton Zeilinger

Abstract

Most working scientists hold fast to the concept of 'realism' - a viewpoint according to which an external reality exists independent of observation. But quantum physics has shattered some of our cornerstone beliefs. According to Bell's theorem, any theory that is based on the joint assumption of realism and locality (meaning that local events cannot be affected by actions in space-like separated regions) is at variance with certain quantum predictions. Experiments with entangled pairs of particles have amply confirmed these quantum predictions, thus rendering local realistic theories untenable. Maintaining realism as a fundamental concept would therefore necessitate the introduction of 'spooky' actions that defy locality. Here we show by both theory and experiment that a broad and rather reasonable class of such non-local realistic theories is incompatible with experimentally observable quantum correlations. In the experiment, we measure previously untested correlations between two entangled photons, and show that these correlations violate an inequality proposed by Leggett for non-local realistic theories. Our result suggests that giving up the concept of locality is not sufficient to be consistent with quantum experiments, unless certain intuitive features of realism are abandoned. ©2007 Nature Publishing Group.

Organisation(s)

Quantum Optics, Quantum Nanophysics and Quantum Information

External organisation(s)

University of Gdańsk

Journal

Nature

Volume

446

Pages

871-875

No. of pages

5

ISSN

0028-0836

DOI

https://doi.org/10.1038/nature05677

Publication date

2007

Peer reviewed

Yes

Austrian Fields of Science 2012

103025 Quantum mechanics

Portal url

https://ucris.univie.ac.at/portal/en/publications/an-experimental-test-of-nonlocal-realism(a4d956bf-f6b3-451a-85cf-25cd4d650698).html