Can a Photon Be Separated from Its Wave?
Journal of Modern Physics
An experiment is proposed in which the overall path taken by a photon is indicated by the timing of a twin herald photon, while a particular segment of that path is determined by interference. The experiment is to be carried out in two parts. In the first, coincident pairs of photons generated by type I spontaneous- parametric-down-conversion are diffracted by a large-width grating to increase the coherence length of their associated waves, and to produce two sources of coincident photons. Upon
... ident photons. Upon experimental confirmation that coincidences have been maintained, one of the sources is used to furnish timing heralds, and the other to send photons to an unequal path interferometer. A photon path through the interferometer via the short arm is indicated by count synchronization with the herald. The exit output port used and final detection location are determined by the phase in the long arm. If output port usage can thus be controlled by the phase in the photon free arm, the path of the photon as particle will have been controlled by interference with an accompanying photon-empty wave.