Classical Interpretation of Ultra-Low Intensity Optical Heterodyning as a Pragmatic Approach to Photon Size Determination

The experimental results on heterodyning the light beams of small intensity (“single photon” level) are presented. It is shown that the semi-classical theory of photon as the wave packet is the most suitable for the interpretation of “single photon” experiments, if only the value of length of photon would be corrected according to our proposal. A study of the statistics of photon distribution during heterodyning of two laser beams shifted in frequency made it possible to experimentally estimate the length of photon. It is shown that photon represents the wave packet of needle-shaped form with spatial length determined by the coherence length of the light radiation and substantially exceeds the wavelength λ. The pulse duration on the output of photomultiplier (PM), originated from single photon, is determined only by processes in the PM and does not refer to the length of photon. It enables the interpretation of obtained results with regard to the well-recognized principles of physics.