Wednesday, January 4, 2012

[my] thoughts on photon experiment by Leonard Mandel

Some speculations on photon-phenomenons:

This experiment performed by Leonard Mandel was presented to me at a lecture back in 2000, to illustrate the “which-way-information-effect”.

The I have understood it:

(fig. 1.01 and 2) Pairs of entangled photons are sent from “A” with the possibility to travel to “B” through “1” or “2”.

When passing through 1 or/and 2 the pair is split and a “red” photon is sent off in a different direction with the possibility to work as an indicator of the travel route of the blue photon.

fig. 1.01   (click on image to enlarge)

fig. 1.02   (click on image to enlarge)

The experiment consists of two parts: one where the red photons from "1" and "2" take different routes, making it possible to tell from which any red photon was sent (fig 1.01). And one where the red photons travel in routes that makes it impossible to distinguish whether any red photon was sent from "1" or "2" (fig. 1.02)

The result of the experiment did show that if it is possible to distinguish between red photons from "1" and from "2" this will influence the behaviour of the blue photon. The result being reactions at "B" indicating that the blue photon had been travelling through ether "1" or "2".

(fig. 1.02): The situation shown in this diagram illustrates the second part of the experiment. Here the red photons from "1" and "2" are made indistinguishable, resulting in a interference pattern at "B".
This is interpreted as the blue photon interfering with “itself” - thus indicating that the blue photon has passed through both "1" and "2".

The big puzzle is then how the blue photon is able to "know" what is going to happen with the red photon - and act accordingly.

When I thought about the experiment something bugged me, and it sprung from the diagram in fig. 1.02, or more precisely form the red line between "1" and "2" in the diagram.
For some reason it seems wrong to me to assume that in some cases "one whole photon" should be situated there. Even if undetected this would make the two situations momentarily identical.
Also the idea of one whole (red) foton being sent form either "1" or "2" while the blue photon passes through both "1" and "2" seems more illogical to me than it ougt to be (even for quantum physics).

This have generated some thoughts which I will try to present in the following:

fig. 1.03   (click on image to enlarge)

#1.: It seems wrong to me to suggest that the impossibility of retrieving “which-way-information” from photons is a phenomenon designed to hide photon behaviour form us.

#2.: #1 causes me to consider the possibility, that the necessity of total absence of “from-where-information” for the red photons, in order to maintain interference pattern at "B", is a consequence of some other photon-necessity.

#3.: (in my view) the assumption of "one whole red photon" being sent form either "1" or "2" in fig. 1.02, makes the two situations too identical, to cause the difference in the behaviour of the blue photon. (this is supposed to be the mysterious point, proven by the experiment, though. But that's just me).

#4.: an additional thought: if “you” travel at the speed of light, time stands still. Since photons travel at the speed of light, then “if I was a photon” and travelled form A to B, I would leave A and arrive at B simultaneously, thus spanning the whole distance. (it has later been pointed out to me that the both-way behaviour occurs in situations with particles travelling at speeds below the speed of light, which disqualifies this part of my sketchy thesis).

In the following video-clips I try to illustrate a way of viewing the photon behaviour, that leads me to suggest an alternative set up (or a part III) of the experiment:

(video 1): illustrates the "expand - contract to react" thesis for photon behaviour. 

The illustration is of the passage of a single photon. And what is sought to be illustrated is a view of the photon as being stretched or flowing out in both directions simultaneously.
This opens up for the idea, that as the two routes of the parts of the photon overlaps (at "B") the photon can split at it's starting-point. (the interference pattern at "B" is for illustration purpose - it will not occur after passage of a single photon, but only after the passage a series of photons).


(video 2): thesis illustrated in the setup where no time+position overlap after split leads to no self-interference.

This illustrates another part of the thesis: the photon flows out in both directions until it has to react with an (other) particle. At that point the photon contracts to deliver its quantum. (I see some problems with accounting for differences in distance traveled vs time of reaction. But if there's something to this thesis, an explanation will/should present itself at some point).


(video 3): thesis illustrated in the "Mandel setup" where time+position overlap leads to self-interference.


(video 4): thesis illustrated in the "Mandel setup" where "no time+position overlap leads to no self-interference.


(video 5): this video suggests an experiment to test the thesis by substituting permanent time+position overlap after "2" (as seen above in video 4) with a momentary time+position overlap (as in video 1) by providing the possibility to self-interfer for the red photon.

If such a setup results in interference patterns at both "B" and "C" this setup will not reveal "which way information" - only "both ways information".
To me such a result would indicate/emphasise that the underlying "photon-necessity" is that the photon "refuses" to be split permanently.
This in itself would be no big surprise, but in my understanding - if an experiment of this kind had a result such as suggested above - it would add a nuance to the understanding of the results of the experiments performed by Mandel. And it might result in ideas of a series of new experiments to explore the behavior further.

Leonard Mantel, interference, idea, wave, entangled, split, detected, detector, pattern, sladrehanke, indicator, physics, science, thesis,