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