Experimental test of nonlocal realistic theories without the rotational symmetry assumption

TL;DR

This paper tests a broader class of nonlocal realistic theories without assuming rotational symmetry, using polarization-entangled photons to experimentally violate a new Leggett-type inequality by 80 standard deviations.

Contribution

It derives an incompatibility theorem applicable to finite measurement settings without rotational symmetry, extending previous tests of nonlocal realistic theories.

Findings

Broader class of nonlocal realistic models excluded

Experimental violation of Leggett-type inequality by 80 standard deviations

No rotational symmetry assumption needed in the test

Abstract

We analyze the class of nonlocal realistic theories that was originally considered by Leggett [Found. Phys. 33, 1469 (2003)] and tested by us in a recent experiment [Nature (London) 446, 871 (2007)]. We derive an incompatibility theorem that works for finite numbers of polarizer settings and that does not require the previously assumed rotational symmetry of the two-particle correlation functions. The experimentally measured case involves seven different measurement settings. Using polarization-entangled photon pairs, we exclude this broader class of nonlocal realistic models by experimentally violating a new Leggett-type inequality by 80 standard deviations.