Abstract

The de Broglie pilot wave theory is a hybrid of quantum and classical concepts that was introduced in order to avoid the conceptual difficulties of the Copenhagen interpretation. According to some versions of this theory, there exist both photons and electromagnetic waves, and the waves are supposed not only to yield probabilities for the photons, but also to have a physical reality. Even an ″empty″ wave, which cannot give rise to photoelectric detection, is supposed to be capable of inducing observable effects. We have tested this theory in an experiment with two cascaded parametric down-converter crystals, in which the idler beam from the first crystal has been shown to induce coherence between the signal beams from the two crystals without inducing any emission. When the photon is removed from the first idler with the help of a beam splitter, the remaining empty wave is found not to induce coherence.

© 1992 Optical Society of America