www.qutools.com quED Manual 27
Denoting the coincidence count rate obtained for the combination of polarizer settings
and , the normalized expectation value of correlations between the measurements
is given by:
where
and
are the polarization orientations perpendicular - that is rotated by - with
respect to α and β. The measurement of coincidence count rate with entangled photons
shows sinusoidal dependence
on the difference angle of the polarizer
orientations, see section 5.1. The same behavior can be predicted for the correlation coefficients
Therefore, for various combinations of orientations
the
CHSH inequality is violated. The maximum violation is obtained if the following conditions on
the polarizer settings are obeyed:
and
giving the upper limit on the violation of the CHSH inequality,
. Quantum entanglement
thus leads to stronger correlations that violate the limit of 2, so that quantum entanglement is
experimentally distinguishable from local realistic models, forcing us to abandon at least one of
the underlying concepts, locality (meaning that local events cannot be affected by actions in
space-like separated regions) or realism (meaning that external reality exists independent of
observation).
For the experiment, any set of orientations fulfilling the conditions given above can be chosen,
e.g.,
and
four separate experimental runs are conducted,
corresponding to the four terms in the definition of the value . Each of the terms
is calculated from four numbers of coincidences, making together 16 count rates which
have to be experimentally taken.
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