Interferometers and Superposition

[Dalo]

This is a spin-off of my thread "Double slit experiments and superposition". In that thread I had limited myself to that kind of experiment to argue that the so-called superpositon of particles was more a theoretical assumption/conclusion than an empirical fact.

People reproached me to limit the discussion artificially and ignore interferometers, especially the Mach-Zehnder interferometer that is considered by many authors as the logical and practical equivalent of the double slit experiment.

I will take this equivalence for granted, even though I think it is much more complicated than that. Still, I cannot deny that the same questions can be asked in both experiments, in particular, the path a particle has taken, and maybe even more importantly, whether observation makes the particles change their path and destroy the ambiguity of the path taken, an effect called interference to emphasize the analogy with the wave phenomenon.

A very nice introduction to The Michelson interferometer can be found here.

This thread will mostly deal with the Mach-Zehnder Interferometer or MZI.

The following drawings, with some minor comments from my part, have been taken from

Quantum physics : a first encounter: interference, entanglement and reality By Valerio Scarani, 2006.

The first drawing shows the principle of a beam splitter which allows 50% of the beam to be transmitted (T) and the other 50% to be Reflected (R).

 

The second picture is a little bit more complicated, but the result is not surprising: 25% of the photons into each detector.

 

We come to our main course, the MZI, which brings us our big surprise. Instead of the expected distribution of 50-50 between RT/TR and RR/TT, all the photons end up on one side, in this case in RT/TR.

 

The last image is a variation on the previous one, with extra mirrors to change the length of one path. The result is also very astonishing. The distribution between both groups seems to depend on the difference between the two main paths. The interpretations given to this phenomenon ignore completely this factor length and concentrate on the "knowledge" that particles seem to have of the different possible paths, and their ability to adapt their behavior accordingly.

 

 

My claim will be: there is no superposition and the particles never change their behavior.

 

 

I advise the reader to print the different drawings to more easily refer to them.

 

Edited December 15, 2017 by Dalo

[Mordred]

So you feel superposition of waves don't exist?

Tell me have you ever worked with music or even an antenna ? We really need to find some common here.

After all Superposition has a huge range of everyday applications. (music, radios, electronic signals, wireless transmition,) example carrier wave, with other frequencies riding said carrier wave which is involved in two way radios.

Reflective waves in an antenna which reduced its wattage. 

MRA scanners. 

XRay machines

Harmonics in electrical circuits

3 phase power

the list goes on

Edited December 15, 2017 by Mordred

[Dalo]

Just now, Mordred said:

So you feel superposition of waves don't exist?

Tell me have you ever worked with music or even an antenna ? We really need to find some common here.

After all Superposition has a huge range of everyday applications. (music, radios, electronic signals, wireless transmition,) example carrier wave, with other frequencies riding said carrier wave which is involved in two way radios.

Reflective waves in an antenna which reduced its wattage. 

MRA scanners. 

XRay machines

the list goes on

Please allow me to present my arguments first.

Also, when dealing with interferometers light is considered exclusively as a particle.

[Mordred]

No it isn't a single photon isn't light. A light is a frequency of multiple particles.

[Dalo]

I have tinkered somewhat with one of the drawings to get this one. It would have been much worse if I had to draw it entirely by hand!

This is simply to make a point: we decide how ambiguous our experiments are.

In this drawing it will be clear each time where the particle went. Of course, this cannot be considered as a valid argument since it simply destroys the interference. It must therefore rather be understood as a general comment on how experiments are set up that claim to arrive at wondrous conclusions.

 

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5 minutes ago, Mordred said:

No it isn't a single photon isn't light. A light is a frequency of multiple particles.

 

I don't understand the objective of this remark. When we use a MZI, we are dealing with photons as particles.

Edited December 15, 2017 by Dalo

[Mordred]

Your using gates which only allow certain polarity states to pass through. Your already removing the other polarities involved for photons. Secondly a gate has a limit on its switching timing. Google an AND gate for TTL devices average switch delay 3 ns. per transistor involved in the gate.

Edited December 15, 2017 by Mordred

[Dalo]

Just now, Mordred said:

Your using gates which only allow certain polarity states to pass through. Your already removing the other polarities involved for photons. Secondly a gate has a limit on its switching timing. Google an AND gate for TTL devices average switch delay 3 ns. per transistor involved in the gate.

I have no idea what you are talking about. We are dealing here with interferometers, not with gates, and until now all I have done is present drawings of the different possibilities as recognized by all authors. If you want to present your own theory, then you are welcome to do so. I will wait until you are finished to give any comment if necessary, and then resume my own argumentation. Unless it will turn out to be completely superfluous.

[Mordred]

Your drawings include Gate symbols common to electronic circuitry. 

http://www.ee.surrey.ac.uk/Projects/CAL/digital-logic/gatesfunc/

Edited December 15, 2017 by Mordred

[Dalo]

This thread has nothing to do with electronic gates. At least, as far as my own intentions are concerned.

[Mordred]

Edit forget the gates the drawings are mirrors so I retract my last. Misread the drawings lol

Edited December 15, 2017 by Mordred

[Dalo]

I remember drawings of electronic gates, so I see how the confusion could have started.

[Mordred]

Yeah long day at work lmao 14 hour work day. Anyways consider the following on refractive index which is involved.

What happens when you pass light through a prism. Is this not an example of seperation of different wavelength frequencies of light? I'm still curious why you find Superposition problematic?

In the Mach Zeeman device the beam splitters? 

Or even rainbows in nature splits light into its constituent frequencies. So I have a hard time understanding why you feel Superposition doesn't exist. We use this principle in thousands of everyday applications. Including electronic signals hence bandpass filters to remove unwanted frequencies in superposition of the desired frequency.

Edited December 15, 2017 by Mordred

[Dalo]

27 minutes ago, Mordred said:

seperation of different wavelength frequencies of light? I'm still curious why you find Superposition problematic?

I don't consider them as being the same thing.

 

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Look at Fig. 1.3. Where would we place detectors to determine the path each particle has taken? Well, without even looking at the detectors, we know that we will be unable to determine the path taken to RT or TR, just as we have no way of knowing if the photon would have hit TT or RR.
Fig. 1.3 is therefore inherently ambiguous. 

This gives us a possible explanation of why when we use a detector, say D1, we get a 50-50 distribution instead of the 100% of Fig.1.3.

D1 cannot exclude the path D2 since a photon could simply end up in RT or TR, explaining why we get the 100%.
In fact wherever we put our detector, there will always be a possible distribution of 0-100%
The only way to exclude any ambiguity would be to use something like My Interferometer.

A single detector, or even all of them at the same time, would therefore destroy the alleged interference, without creating a mystery. After all, we still have Fig.1.4 and the effects of the factor length. Even though we have no idea how it works.
 

[Mordred]

1 hour ago, Dalo said:

I don't consider them as being the same thing.

 

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That ranks right up there with one of the dumbest statements I have ever heard on any forum I've ever come across.

 Sorry but it is precisely the same thing. By the literal definition of the term superppsition.

[Dalo]

Just now, Mordred said:

That ranks right up there with one of the dumbest statements I have ever heard on any forum I've ever come across.

 Sorry but it is precisely the same thing. By the literal definition of the term superppsition.

noted.

[Mordred]

I certainly hope so.

  Have you never even looked at how Snells laws of refraction applies to the beam seperator of the interferometers you posted above?

It is precisely the same thing if you take your fingers out of your ears.

Edited December 15, 2017 by Mordred

[Strange]

3 hours ago, Dalo said:

Also, when dealing with interferometers light is considered exclusively as a particle.

Huh? Interferometers are easily (much more easily) explained by classical wave behaviour than by photon models. The former requires schoolboy arithmetic, the latter requires quantum electrodynamics and the path integral. 

So I suppose this is going to be another “I think science is wrong so I am going to refuse to understand it and make stuff up instead” thread. 

Good luck. I’m sure it will be just as successful as the others. 

[Dalo]

The reference provided by @swansont is much more challenging. I will therefore first present their specific version of MZI, and try to simplify it without betraying their intentions.

The first original drawing is therefore quite cluttered, as all elements used at one time or another seem to have been given a place at the same time.

 

 

I have taken the liberty of taking out all the elements that are not part of a simple MZI.

 

 

The last image, for now, is the end result.

As you see, this is much more complicated than what Scarani had presented. 

******************************************

11 minutes ago, Strange said:

Huh? Interferometers are easily (much more easily) explained by classical wave behaviour than by photon models. The former requires schoolboy arithmetic, the latter requires quantum electrodynamics and the path integral. 

So I suppose this is going to be another “I think science is wrong so I am going to refuse to understand it and make stuff up instead” thread. 

Good luck. I’m sure it will be just as successful as the others. 

Well, I will be very grateful to you if you could give me a reference where this issue, the disappearance of interference patterns, is treated with wave theory. I am especially interested in how low intensity is treated exclusively with wave theory. I am simply using the examples given by people more knowledgeable than me. Scarani is abundantly clear, citing Feynman (volume 3 of the Lectures on Physics, which I happen to also have read), as are the (students) authors Swansont suggested.

I cannot upload the pdf file because of size limitation. It will have to wait for the following post.

Edited December 15, 2017 by Dalo

[swansont]

43 minutes ago, Dalo said:

The reference provided by @swansont is much more challenging. I will therefore first present their specific version of MZI, and try to simplify it without betraying their intentions.

The first original drawing is therefore quite cluttered, as all elements used at one time or another seem to have been given a place at the same time.

 

 

I have taken the liberty of taking out all the elements that are not part of a simple MZI.

 

 

The last image, for now, is the end result.

As you see, this is much more complicated than what Scarani had presented. 

 

Really? Source, two beamsplitters, two mirrors, detector. Looks just as simple/complicated to me.

[Dalo]

Let us keep on analyzing the information given. The information given in Fig.5 can be represented by two drawing.

 

As you can see, the second drawing is equivalent to a simple drawing of a MZI without any additions. In such a case, we have therefore NO INTERFERENCE PATTERN.

 

Edited December 15, 2017 by Dalo

[swansont]

3 hours ago, Dalo said:

I don't consider them as being the same thing.

 

**********************************************

Look at Fig. 1.3. Where would we place detectors to determine the path each particle has taken? Well, without even looking at the detectors, we know that we will be unable to determine the path taken to RT or TR, just as we have no way of knowing if the photon would have hit TT or RR.
Fig. 1.3 is therefore inherently ambiguous. 

 

Fig 1.3 is not a which-path experiment, it is an interferometer. (Incidentally, your version of an interferometer is not an interferometer)

47 minutes ago, Dalo said:

Well, I will be very grateful to you if you could give me a reference where this issue, the disappearance of interference patterns, is treated with wave theory. I am especially interested in how low intensity is treated exclusively with wave theory. I am simply using the examples given by people more knowledgeable than me. Scarani is abundantly clear, citing Feynman (volume 3 of the Lectures on Physics, which I happen to also have read), as are the (students) authors Swansont suggested.

Interferometers and which-path experiments are not synonymous. Strange was talking about interferometers in general, which are, indeed easily explained with wave theory.

3 minutes ago, Dalo said:

Let us keep on analyzing the information given. The information given in Fig.5 can be represented by two drawings.

 

As you can see, the second drawing is equivalent to a simple drawing of a MZI without any additions. In such a case, we have therefore NO INTERFERENCE PATTERN.

And yet the lab write-up shows an interference pattern.

[Dalo]

12 minutes ago, swansont said:

Fig 1.3 is not a which-path experiment, it is an interferometer. (Incidentally, your version of an interferometer is not an interferometer)

Well, I suggest you get a copy of Scarani's book. Unless you already have it and know the author for being a crackpot. The problem is that would make of Alain Aspect, who wrote the introduction, also a crackpot.

****************************************************

getliffe_lab_2_final.pdf

as promised

Edited December 15, 2017 by Dalo

[swansont]

9 minutes ago, Dalo said:

Well, I suggest you get a copy of Scarani's book. Unless you already have it and know the author for being a crackpot. The problem is that would make of Alain Aspect, who wrote the introduction, also a crackpot.

****************************************************

getliffe_lab_2_final.pdf

as promised

I'm not critiquing the book and have not called anybody a crackpot. I'm trying to correct your interpretation, which is wrong. Interferometers are used for lots of experiments. "Which-path" experiments are a small subset of those. When people give a general example of an interferometer, it is quite likely they do not have a which-path experiment in mind.

[Dalo]

11 minutes ago, swansont said:

I'm not critiquing the book and have not called anybody a crackpot. I'm trying to correct your interpretation, which is wrong. Interferometers are used for lots of experiments. "Which-path" experiments are a small subset of those. When people give a general example of an interferometer, it is quite likely they do not have a which-path experiment in mind.

You should really consult the book and tell me if I am wrong. The drawingsI have presented are taken directly from the book, and the appellation of MZI comes from the author, not from me.

As to whether this can be counted as a which-path experiment, I wonder how relevant that is for the subject of the thread which is still: does observation change the results of the experiment?

***********************************************

28 minutes ago, swansont said:

And yet the lab write-up shows an interference pattern.

I am simply repeating what's in the text of the pdf file you have linked in the other thread:

"We observed that without a polarizer no interference pattern was observed because light exiting the interferometer contained which-path information." p.6

Edited December 15, 2017 by Dalo

[swansont]

9 minutes ago, Dalo said:

You should really consult the book and tell me if I am wrong. The drawingsI have presented are taken directly from the book, and the appellation of MZI comes from the author, not from me.

I am telling you that you are wrong. A general representation of an interferometer is not going to be a "which path" experiment. You are wrong to assume that it is.

9 minutes ago, Dalo said:

As to whether this can be counted as a which-path experiment, I wonder how relevant that is for the subject of the thread which is still: does observation change the results of the experiment?

Presenting misinformation and holding a misconception certainly can't help with that.

9 minutes ago, Dalo said:

***********************************************

I am simply repeating what's in the text of the pdf file you have linked in the other thread:

"We observed that without a polarizer no interference pattern was observed because light exiting the interferometer contained which-path information." p.6

But they were using a which-path experimental setup, and not a "simple" MZI which you claimed gives no interference pattern.