Reconsidering the relation between "matter wave interference" and "wave-particle duality"

TL;DR

This paper critically examines the traditional concept of wave-particle duality, arguing that recent interference experiments with large molecules show simultaneous wave and particle features, challenging the usefulness of the duality notion in quantum physics.

Contribution

The paper provides a historical analysis of wave-particle duality and demonstrates through experiments that molecules exhibit dual features simultaneously, questioning the validity of the duality concept.

Findings

Interference experiments with large molecules support dual features.

Diffraction depends on localized molecular structure.

Wave-particle duality concept is outdated in modern quantum physics.

Abstract

Interference of more and more massive objects provides a spectacular confirmation of quantum theory. It is usually regarded as support for "wave-particle duality" and in an extension of this duality even as support for "complementarity". We first give an outline of the historical development of these notions. Already here it becomes evident that they are hard to define rigorously, i.e. have mainly a heuristic function. Then we discuss recent interference experiments of large and complex molecules which seem to support this heuristic function of "duality". However, we show that in these experiments the diffraction of a {\em delocalized} center-of-mass wave function depends on the interaction of the {\em localized} structure of the molecule with the diffraction element. Thus, the molecules display "dual features" at the same time, which contradicts the usual understanding of wave-particle duality. We conclude that the notion of "wave-particle duality" deserves no place in modern quantum physics.