Poisson spot with single photons

[Quant]

I suppose that when carried out a Poisson spot with photons one at a time
should have to be observed.
I tried to find such experiment but i got 0 result. it seems that nobody cared
about that. But i think such experiment would be very important as it will show
that the wavefunction can have macroscopic dimension (not just 0.5 mm but
much more).
So why there are not experiments for Poisson spot with single photons?

 

[pines-demon]

I found a poster about it: https://digitalcommons.cwu.edu/source/2020/COTS/96/

 

[Quant]

Thank you

I found a poster about it: https://digitalcommons.cwu.edu/source/2020/COTS/96/

Thank You @pines - demon. As far as I interprete the data the obscuring disc diameter is 4 cm.
Do you think this diameter can be greater? In my opinion the wavefunction of a photon should be
a sphere with R=c.t so much greater diameter should be possible in principle. Then the Arago
spot may be possible with opposite points/parts of the sphere using mirrors if this is true, do you think?

 

[Vanadium 50]

If you think it is important, why not do the experiment yourself? That's probably more effective than complaining on a message board that physicists are all out measuring what they are interested in instead of what you are interested in.

 

[Nugatory]

Thank you

Thank You @pines - demon. As far as I interprete the data the obscuring disc diameter is 4 cm.
Do you think this diameter can be greater? In my opinion the wavefunction of a photon should be
a sphere with R=c.t so much greater diameter should be possible in principle.

"Wavefunction of a photon" is a somewhat tricky idea, in part because when we're talking wavefunctions we're usually talking non-relativistic QM - and photons are among the most egregiously relativistic things around. But with that said, there is no reason to doubt that the probability distribution that leads to dot-at-a-time interference patterns in single-photon experiments can be calculated in the same way no matter the diameter of the sphere.
And that's why there's not a lot of interest in actually doing the experiment with larger spheres: it's a lot of work with small chances of learning anything we didn’t already know.

Then the Arago
spot may be possible with opposite points/parts of the sphere using mirrors if this is true, do you think?

Now this I totally do not understand. Where do mirrors come into it? What experimental setup are thinking of, and having calculated the expected result, what do you expect to learn from this setup.

 

[pines-demon]

Thank you

Thank You @pines - demon. As far as I interprete the data the obscuring disc diameter is 4 cm.
Do you think this diameter can be greater?

If I understand the graph correctly the diameter of the spot is 1 cm.

In my opinion the wavefunction of a photon should be a sphere with R=c.t so much greater diameter should be possible in principle.

Physically yes, in practice it depends, one would have to take a look at the experimental set-up, but I am no good at interpreting optics experiments, see other comments.

 

[Quant]

If you think it is important, why not do the experiment yourself? That's probably more effective than complaining on a message board that physicists are all out measuring what they are interested in instead of what you are interested in.

Short answer: money, time, lot of efforts. But as in fact the classical EM wave is a collection of the separate single photon's "wavefunctions"/probabilties, a classical experiment is also a confirmation for the spherical propagation of "WF"/Pr of single photons.

 

[Quant]

If I understand the graph correctly the diameter of the spot is 1 cm.

Physically yes, in practice it depends, one would have to take a look at the experimental set-up, but I am no good at interpreting optics experiments, see other comments.

1 cm? Why? The shadow spreads from -20 mm to 20 mm. Or i don't take in account the distance behind the disk/ball they used?
I got the idea the Arago spot should exist by solar eclipse? Any info?

 

[Quant]

"Wavefunction of a photon" is a somewhat tricky idea, in part because when we're talking wavefunctions we're usually talking non-relativistic QM - and photons are among the most egregiously relativistic things around.

Yes surely though there are some variants like Byalnizki-Birula, Sipe etc.

But with that said, there is no reason to doubt that the probability distribution that leads to dot-at-a-time interference patterns in single-photon experiments can be calculated in the same way no matter the diameter of the sphere.

Do you agree that as the EM wave is a collection of single photon's probabilities, classical (e.g. huge number of photons) Arago spot experiments confirm the spherical spreading of probability for single photons?
Do you have opinion about Arago spot by solar eclipse?

And that's why there's not a lot of interest in actually doing the experiment with larger spheres: it's a lot of work with small chances of learning anything we didn’t already know.
Now this I totally do not understand. Where do mirrors come into it? What experimental setup are thinking of, and having calculated the expected result, what do you expect to learn from this setup.

If the probability spreads like a sphere (for a source of the photon - a free stationary atom) than probabilities from the opposite ends of that sphere should be able to interfere but mirrors are needed to direct them in one point. Of course this maybe done with fiber optics. Expected result is confirmation of spherical propagation of probability for single photon.
As you think this is completely sure I would say that in all books (say 20) i read on QM there is not a word about how does the probability propagation of single photons look like.

 

[Vanadium 50]

Short answer: money, time, lot of efforts

That's fine, but don't expect people to be convinced by the argument "my time is too valuable. Your time, on the other hand...."

Or, in another context: "Asps. Very dangerous. You go first."

 

[Vanadium 50]

Further, the classical version of this is done by freshman university students. If you want to do this one photon at a time, you start with that, add a dark box, a digital camera, an optical filter, and some stacking software of the kind used by amateur astronomers. That's it.

You don't need a particle accelerator, or a nuclear reactor, or a rocket, or even a vacuum chamber.

 

[Vanadium 50]

I got the idea the Arago spot should exist by solar eclipse? Any info?

Another "it's too much work for me to do - you guys do it!"

You had two options:
A. Plug in the numbers into the equation Wikipedia gives you.
B. Type that into Google.

Again, you decided your time was too important, but our time isn't. How to win friends and influence people.

The answer is "no", as the sun is not even remotely close to the light source requirements.

 

[Quant]

The answer is "no", as the sun is not even remotely close to the light source requirements.

What requirements are you talking about? Every photon from the visible sun disk should
propagate on its own with its own 'wave function'/probability distribution which must pass
the both sides of the moon (because its in almost vacuum) and then interfere only with itself.
So the sun disk is a collection of point sources and each must produce an intfr pattern (of
different photons from that point). As the other points don't intf negatively with any other
point there should be a small image of the sun in the centre of the moon shadow. It would
of course be very faint and obscured by many other sources. The non ideal vacuum will also
diminish this Arago spot formation.

 

[Nugatory]

What requirements are you talking about

Coherence if you anticipate a visible pattern predicted by classical wave optics. Single-photon states if you’re thinking of the dot-at-a-time patterns built up by quantum effects.

 

[Vanadium 50]

What requirements are you talking about?

A point source. The sun is not even approximately one.
A smooth target. The moon is not even approximately one.

 

[Vanadium 50]

And as a PS, the reason you don't see the Arago/Poisson/Fresnel Spot in an eclipse is classical, not quantum mechanical.

 

[PeterDonis]

the classical EM wave is a collection of the separate single photon's "wavefunctions"/probabilties

Only in a very, very vaguely heuristic sense.

in all books (say 20) i read on QM there is not a word about how does the probability propagation of single photons look like.

That should be an indication to you that the concept you are trying to use here, to the extent it even makes sense (see above), is not a very useful one.