Evidence of pair-correlation of which-way effects in the asymmetrical double-slit interference

Abstract

The problem of physical reality in quantum mechanics has been raised since the famous Einstein-Bohr debate at the 5th Solvey conference in 1927. Ignoring the reality of a quantum matter existing independent of human observation, Bohr proposed an interpretation through the principle of complementarity, which negates simultaneous measurements of both characteristics of wave-particle duality. Until now, the issue remains unresolved and has received increasing attention over the past decade. Here we show for the first time a novel experimental correlation between two substitutionary which-way effects in asymmetrical double-slit experiments performed under the far-field Fraunhofer condition. The identifiable paired fringes can be seen in the self-interference spectra of single photons, travelling through different paths as point-like particles. The correlation greatly improves the confidence level and turns the present experiment into unambiguous evidence for the simultaneous measurement of wave-particle duality to the ontological physical reality of photons against the orthodox interpretation of quantum mechanics.