Re: The time it takes to emit one photon
- From: nightlight <nightlight@xxxxxxxxxxxxxx>
- Date: Mon, 3 Oct 2005 07:35:44 +0000 (UTC)
> Modern experimental techniques allow one to emit a single
> photon of visible light at a time.
You should read Quantum Optics term "single" photon as Glauber's
"single" "photon" i.e. under the QO/Glauber counting conventions (see
earlier messages), which is not what anyone otside QO means under the
terms "single" or "photon". Additionally, what Quantum Opticians call
"photon" is not the regular Dirac photon (a single free field mode
quantum with sharp energy-momentum i.e. the state [a_k+]|0>), but any
(generally infinite) superposition of single D-photons over different
frequencies (or wave 4-vectors k, cf. Eq. 12.11-26 pp 636 in [1]).
Regarding the "single" part, it is under the same "G-counting" (the
counting after the Glauber's prescribed subtractions) that yields
G-violations of Bell inequalities and photon G-anticorrelations. This
is exactly what I was explaining to you (and the other fellow in the
parallel thread) in all the previous posts with the critical example of
the anticorrelation experiments (which were devised precisely to
demonstrate the "single" "photons" since all other experiments, such as
photo-effect, Compon effect,... etc, can't do that, cf. intro in [2]).
The "G-single" which is all that the "modern experimental techniques"
claim to obtain (unless they outright cheat like the authors of [2], in
order to claim more) means it is at best the Poissonian distribution
(or wider) of photo-counts with the average much smaller than 1. That
is, as already explained at length, indistingushable from the perfectly
classical EM field effect.
> The photon has energy of a few electron-volts. This is about
> the same energy as required to excite one active center on the
> scintillating screen. If (according to your theory) we assume
> that the photon's energy is being spread over extended
> wave, then the only way the scintillating center can be excited
> is if the wave somehow collapses.
First, there is no "my theory" anywhere here (that's all old hat, noted
long ago by Schrodinger and de Broglie through Barut, Jaynes, Marshall,
Santos,... in recent years). Just beacause they didn't teach you any of
it at school, it doesn't mean I making it up. I gave you plenty of
references, which you show not even the slightest sign of having ever
heard of before or even having any of them checked out after being
alerted to their existence (as your label "your theory" indicates, one
from the so far uninterrupted series of non sequitur,
back-to-square-zero, "replies").
Second, as explained and referenced earlier, the photo-absorption
energy argument you recite here hasn't been valid ever since
Schrodinger wave mechanics, using plain classical EM fields, had
explained quantitatively the photo-effect (and Comprton effect) in late
1920s. See the intro sections in [2] for a brief history and some
references on this question. Since, judging from your previous
behaviour in this thread, you won't read it anyway, I will just quote
the very first paragraph from [2]:
Students often believe that the photoelectric effect, and
Einstein's explanation of it, proves that light is made of photons.
This is simply not true; while the photoelectric effect
strongly suggests the existence of photons, it does not demand
it [1],[2]. It was shown in the 1960s by Lamb and Scully
that the photoelectric effect can be explained by assuming
that the detector atoms are quantized, but that the field is not
i.e., by assuming light to be a classical wave!. This explanation
is based on the semiclassical model of photoelectric
detection, which we will discuss further below [3],[4].
The authors of [2] cite a relative late refutation (from 1960s), which
was when the argument reached and got refuted in the Quantum Optics
circles and language. The resonant absorption of classical EM field by
the Schrodinger matter field is sufficient to account for the effect.
It is no more mysterious than a pocket radio absorbing "single" photons
over a kilometer in size (and wavelength). The full QED radiative
corrections (which are outside of the QO arguments) are also accounted
for (to at least alpha^5 order) with the same classical theory, as
shown within the Barut's Self-field ED (which uses the full coupled
classical Maxwell-Dirac or Maxwell-Schrodinger fields, hence the
solutions of the set of nonlinear PDEs).
You first need to study some of the cited literature from previous
posts on the subject (beyond the popular and pedagogical materials)
before we can advance here to at least begin discussing the same topic.
I am not going to follow you to square zero on every message.
1. L. Mandel, E. Wolf "Optical Coherence and Quantum Optics"
Cambridge Univ. Press., Cambridge (1995)
2. J.J. Thorn, M.S. Neel, V.W. Donato, G.S. Bergreen, R.E. Davies,
M. Beck
"Observing the quantum behavior of light in an undergraduate
laboratory"
Am. J. Phys., Vol. 72, No. 9, 1210-1219 (2004).
a) Paper:
http://marcus.whitman.edu/~beckmk/QM/grangier/Thorn_ajp.pdf
b) Experiment Home Page: http://marcus.whitman.edu/~beckmk/QM/
c) On how it cheats:
http://www.physicsforums.com/showthread.php?t=71297
{ Posted on Oct 2 2005, 19:57 EST }
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