Loopholes in Bell inequality tests of local realism
Abstract
Bell inequalities are intended to show that local realist theories cannot describe the world. A local realist theory is one where physical properties are defined prior to and independent of measurement, and no physical influence can propagate faster than the speed of light. Quantummechanical predictions for certain experiments violate the Bell inequality while a local realist theory cannot, and this shows that a local realist theory cannot give those quantummechanical predictions. However, because of unexpected circumstances or ‘loopholes’ in available experiment tests, local realist theories can reproduce the data from these experiments. This paper reviews such loopholes, what effect they have on Bell inequality tests, and how to avoid them in experiment. Avoiding all these simultaneously in one experiment, usually called a ‘loopholefree’ or ‘definitive’ Bell test, remains an open task, but is very important for technological tasks such as deviceindependent security of quantum cryptography, and ultimately for our understanding of the world.
This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘50 years of Bell’s theorem’.
 Publication:

Journal of Physics A Mathematical General
 Pub Date:
 October 2014
 DOI:
 10.1088/17518113/47/42/424003
 arXiv:
 arXiv:1407.0363
 Bibcode:
 2014JPhA...47P4003L
 Keywords:

 Quantum Physics
 EPrint:
 42 pages, 2 figures