Violation of local realism with freedom of choice.
Bell's theorem shows that local realistic theories place strong restrictions on observable correlations between different systems, giving rise to Bell's inequality which can be violated in experiments using entangled quantum states. Bell's theorem is based on the assumptions of realism, locality, and the freedom to choose between measurement settings. In experimental tests, "loopholes" arise which allow observed violations to still be explained by local realistic theories. Violating Bell's inequality while simultaneously closing all such loopholes is one of the most significant still open challenges in fundamental physics today. In this paper, we present an experiment that violates Bell's inequality while simultaneously closing the locality loophole and addressing the freedom-of-choice loophole, also closing the latter within a reasonable set of assumptions. We also explain that the locality and freedom-of-choice loopholes can be closed only within nondeterminism, i.e., in the context of stochastic local realism.
Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Vienna, Austria.
Thomas
T
Scheidl
Rupert
R
Ursin
Johannes
J
Kofler
Sven
S
Ramelow
Xiao-Song
XS
Ma
Thomas
T
Herbst
Lothar
L
Ratschbacher
Alessandro
A
Fedrizzi
Nathan K
NK
Langford
Thomas
T
Jennewein
Anton
A
Zeilinger