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  • $\begingroup$ Interesting, especially as an experiment is proposed. the question is whether it effectively measures the single photon twice, or different photons on each measurement (similar to the use of two photon emission for twin slit checking). I believe there is already a similar experiment for producing super intense pulses by the reverse process with a chirped laser (FROG - en.wikipedia.org/wiki/Frequency-resolved_optical_gating) $\endgroup$
    – Philip Oakley
    Commented Nov 17, 2018 at 21:43
  • $\begingroup$ However, I'm still of the opinion that each photon has a single precise frequency defined by its energy. And that it can only have one of two polarisations, left and right circular (otherwise that aspect would not be quantum). It's likely that the rotational frequency is the constant, while the direction of travel shape is more wavelet, and it is ultimately quaternionic (as per Maxwell, Art 618/9 IIRC). $\endgroup$
    – Philip Oakley
    Commented Nov 17, 2018 at 22:10
  • $\begingroup$ Per the Heisenberg uncertainty principle, the product of energy uncertainty and time of emission (which translates to phase) is always finite. Every laser has a finite linewidth, and that line width is a characteristic of the photons comprising the laser's emission. That is, the frequency of each photon is indeterminate within the line width of the laser. $\endgroup$
    – S. McGrew
    Commented Nov 18, 2018 at 1:24
  • $\begingroup$ For a laser we are producing a very large number of photons. There are various ensemble statistics therein. However in this case we are looking at just a single photon, so the 'statistic' aspect wouldn't be valid here. At the moment we are in a catch 22 scenario where it is [normally] claimed that we cannot in anyway measure or infer the measurement of these two apparently distinct characteristics because the theory suggests that they are bound to the same fundamental constant (which may have a systematic error, but no experimental error...) $\endgroup$
    – Philip Oakley
    Commented Nov 19, 2018 at 23:56
  • $\begingroup$ That argument could be used to say that no photon exists in a mixed state of any sort at all. In practice, we produce a lot of photons under identical conditions and measure the state of each photon individually, as in the single-photon double slit experiment. Even though the individual measurements yield definite results, the measurements all together are taken as proof that the photons are all in the same mixed state. $\endgroup$
    – S. McGrew
    Commented Nov 20, 2018 at 0:07