Ruling Out Multi-Order Interference in Quantum Mechanics

TL;DR

This paper reports an experiment with photons that tests the validity of Born's rule in quantum mechanics by searching for higher-order interference effects, finding no deviation and thus supporting the standard theory.

Contribution

The authors conducted a three-slit photon experiment that tightly bounds third-order interference, providing experimental evidence against deviations from Born's rule.

Findings

Bound the magnitude of three-path interference to less than 1% of two-path interference

Ruled out third and higher order interference within experimental accuracy

Supported the validity of Born's rule in both semi-classical and quantum regimes

Abstract

Quantum mechanics and gravitation are two pillars of modern physics. Despite their success in describing the physical world around us, they seem to be incompatible theories. There are suggestions that one of these theories must be generalized to achieve unification. For example, Born's rule, one of the axioms of quantum mechanics could be violated. Born's rule predicts that quantum interference, as shown by a double slit diffraction experiment, occurs from pairs of paths. A generalized version of quantum mechanics might allow multi-path, i.e. higher order interferences thus leading to a deviation from the theory. We performed a three slit experiment with photons and bounded the magnitude of three path interference to less than 10-2 of the expected two-path interference, thus ruling out third and higher order interference and providing a bound on the accuracy of Born's rule. Our experiment is consistent with the postulate both in semi-classical and quantum regimes.