This article ruled out third- and higher-order interference and providing a bound on the accuracy of Born's rule.

The probability density to find
a particle at position and at time is given by
A double-slit diffraction experiment is a direct
consequence of this rule; the probability to detect
a particle at r after passing through an aperture
with two slits, A and B, is given by
The corresponding
(second-order) interference term can be defined as
We define the third-
order interference term for a three-path
configuration (mutually exclusive) as the deviation of from the sum of the individual
probabilities and the second-order interference terms: