A How does QFT treat Young’s Double-Slit Experiment?

[Quant]

TL;DR Summary

The QM wavefunction/probability distribition in view of QFT modes (in cavity)

How does QFT treat the Young’s DSE? Is there a wave function (wave packet) attached (and created at the moment of launching of the photon) or the modes of the EM quantum field are pre-existing due to experimental configuration (including the screen) and do they play the role the wave function is supposed to do in QM?

 

[Nugatory]

The interference demonstrated by Young's double-slit experiment is a classical phenomenon explained by the classical wave solutions of Maxwell's equations of classical electrodynamics - there is no quantum mechanics involved. Quantum mechanical double-slit experiments are a different thing, and it is unfortunate that the analogy between these and Young's experiment is so often used in popularizations.

The essential characteristic of the quantum-mechanical experiment is that the interference pattern builds up one detection at a time, a behavior that is cannot be explained by classical physics. At a very rough level, the quantum field theory explanation works by writing the electromagnetic field as a sum of oscillatory modes (in momentum space, not position space); in this form we can calculate the probability of a particular mode absorbing or releasing one quantum of energy at a given point in spacetime.
If you are not already comfortable with this approach to quantum physics, you could do worse than working through Lancaster and Blundell's book "Quantum Field Theory for the Gifted Amateur".

 

[Quant]

Thanks for reply Nugatory.

Why do want me to read Gifted Amateur? Because of modes or because of DSE. As is obvious by my question i know about modes. In k space. So - instantaneous whole space occupying vacuum states of 1/2 hv which are on the brink of reality (Casimir) Existing from start of Universe. About DSE i found nothing in the book (i took a brief look on the content there are usual things - operators, propagators, Feynman etc. On the search i didnt find nothing about quantum DSE.

Yes im really looking on a QFT book on DSE. Have you got it in this one?
For me is very interesting what you mean by 'at a very rough level'. What is beyond modes? In case of DSE not interaction of fields!

 

[Nugatory]

Why do want me to read Gifted Amateur?

You asked how quantum field theories treat the double slit experiment, understanding quantum field theories seems like a natural first step in answering that question, and Lancaster and Blundell is one of the better ways for a non-specialist to take that first step, so that's what I suggested. You are of course free to ignore that suspicion, especially if you're already comfortable with that formalism (although your original post suggests that you are not).

Yes im really looking on a QFT book on DSE.

I doubt that such a book exists, more likely the double-slit experiment will show up as an exercise at the end of some chapter in a more general treatment of QFT. But for what it is worth, googling for "quantum field theory double slit experiment pdf" brings up some relevant-looking papers as well.

For me is very interesting what you mean by 'at a very rough level'.

It means that I wrote a single sentence to summarize a much larger and more complex topic.

 

[Quant]

You asked how quantum field theories treat the double slit experiment, understanding quantum field theories seems like a natural first step in answering that question, and Lancaster and Blundell is one of the better ways for a non-specialist to take that first step, so that's what I suggested. You are of course free to ignore that suspicion, especially if you're already comfortable with that formalism (although your original post suggests that you are not).

My post suggests that i am well acknowledged with QFT (also Lancester et al is not for not gifted gifted or even genious amateurs, just maybe for very good mathematicians but i doubt they do and need physics). Regretful QFT is more math construction with few physical constrains. I dont understand why QFT as heir of QM totally ignores the central experiment from which QM started and which stays unsolved in QM for 100 y.

I doubt that such a book exists, more likely the double-slit experiment will show up as an exercise at the end of some chapter in a more general treatment of QFT. But for what it is worth, googling for "quantum field theory double slit experiment pdf" brings up some relevant-looking papers as well.

Yes surely. But this can take much time. Maybe better to ask AI. Maybe groups are not worth anymore.

It means that I wrote a single sentence to summarize a much larger and more complex topic.

I wonder can you be concrete a little.

 

[PeterDonis]

Maybe better to ask AI

Not for discussion here; PF does not permit using AI as a reference or a source.

 

[PeterDonis]

I dont understand why QFT as heir of QM totally ignores

It doesn't, as @Nugatory has already explained.

the central experiment from which QM started

QM didn't start from the double slit experiment. QM discussions for lay people like to focus on it, but as @Nugatory has already explained, the interference shown is explainable by classical electromagnetism and does not require QM. The aspects that do require QM are not unique to this experiment and were not initially explored using it.

and which stays unsolved in QM for 100 y.

I have no idea why you think the double slit experiment is "unsolved in QM for 100 y".

Maybe groups are not worth anymore.

If you're not going to pay any attention to responses you get when you ask questions, then no, a place like this is not going to help you.

 

[PeterDonis]

My post suggests that i am well acknowledged with QFT

No, actually it suggests the opposite, since someone who was familiar with QFT would not even need to ask the questions you ask in your OP, because such a person would know that those questions don't even make sense in the context of QFT.

 

[PeterDonis]

I wonder can you be concrete a little.

What @Nugatory was describing was the general approach to QFT that you will find in many QFT textbooks and which has nothing to do with the double slit experiment in particular. Indeed, the double slit experiment is probably the least interesting QM experiment from a QFT point of view, because a QFT analysis adds nothing useful to the analysis you can do with just basic QM. So if you insist on looking for a QFT treatment of the DSE in particular, you are likely to be disappointed, because physicists generally don't waste time on things that don't add anything useful to what they already know.

 

[hutchphd]

TL;DR Summary: The QM wavefunction/probability distribition in view of QFT modes (in cavity)

How does QFT treat the Young’s DSE?

Could we use english words please??? Or at least define the G. D. (that;s God-Damned) acronyms? This is not a NASA engineering report.
Yes I am PO'd

 

[PeterDonis]

@hutchphd the thread title does make it pretty clear what DSE stands for.

 

[berkeman]

Could we use english words please?

@hutchphd the thread title does make it pretty clear what DSE stands for.

I don't know if Hutch could have been seeing a cached version of the title (which originally just used DSE), but I changed the title to make it more descriptive around 0700 on Monday.

 

[Vanadium 50]

don't know if Hutch could have been seeing a cached version of the title

That definitely happens.

OP, you seem to be offended that the references you are being pointed to are too simple for you. At the same time, you are writing things that people are finding surprising. (100 years) Why not adopt a different approach - show us the calculation and where you are stuck.

 

[Quant]

That definitely happens.

OP, you seem to be offended that the references you are being pointed to are too simple for you.

No just are usual qft stuff which i passed many years before. The point is they not mention DSE at all.

At the same time, you are writing things that people are finding surprising. (100 years) Why not adopt a different approach - show us the calculation and where you are stuck.

De Broglie published his thesis in 1924. What is the right interpretation of QM now?
Do you think Copenhagen version is ultimate? Why then do people offer more interpretations?

 

[Vanadium 50]

<sigh>

I see you didn't start the calculation. (Just as in a past thread you didn't want to set up a few dollar experiment to demonstrate what you were looking for. Pity. People will draw the conclusion that you didn't do this because, despite your claims, you don't actually know how to do this calculation, nor do you understand QFT. Perhaps that not true, but surely you can see how people will jump to this conclusion.

 

[Quant]

It doesn't, as @Nugatory has already explained.


QM didn't start from the double slit experiment.

Really? DSE was evidence for corposcular+wavelike nature of light which promped de Broglie to introduce material waves.

QM discussions for lay people like to focus on it,

Feynman said that the only mistery of QM is the DSE.

but as @Nugatory has already explained, the interference shown is explainable by classical electromagnetism and does not require QM. The aspects that do require QM are not unique to this experiment and were not initially explored using it.

It WAS until the single photon DSE. Maxwell EM theory is as right as Newton Mechanics. We know that they are just very good approximations.

I have no idea why you think the double slit experiment is "unsolved in QM for 100 y".

Look at my response to Vanadium.

If you're not going to pay any attention to responses you get when you ask questions, then no, a place like this is not going to help you.

You can now close the thread.
i am more certain these groups are waste of time sticking too well established clichee.

[Post edited to remove an insult]

 

[Vanadium 50]

i am more certain these groups are waste of time sticking too well established clichee.

Yeah, it's called science.

 

[berkeman]

sticking too well established clichee.

There are two ways to parse your statement (with appropriate corrections)...

 

[PeterDonis]

DSE was evidence for corposcular+wavelike nature of light

Not in the 1920s, it wasn't. The DSE wasn't evidence for light quanta (photons) until it was possible to do it with a light source of low enough intensity that single photon impacts could be observed on the detector. That wasn't done until the 1980s.

which promped de Broglie to introduce material waves.

QM had already started well before that, with Planck's model for black body radiation in 1900, followed by Einstein's model of the photoelectric effect in 1905, and then the Bohr-Sommerfeld model of the hydrogen atom in, IIRC, 1913.

Also, when de Broglie proposed his hypothesis, he did not reference the DSE as evidence for the corpuscular nature of light (because at the time it wasn't--see above), he referenced Einstein's model of the photoelectric effect in 1905.

Feynman said that the only mistery of QM is the DSE.

He said the DSE, if you do it in a way that allows single photon detections, illustrates the central mystery of QM. He never said it was the only such experiment.

Look at my response to Vanadium.

Your response had nothing to do with the claim of yours that I asked about. The fact that there is no single generally accepted interpretation of QM has nothing to do with QM's ability to make accurate predictions, which is all that is required for the DSE, or anything else, to be "solved". Nature doesn't care whether humans have an interpretation of QM, or any other model, that we like. Nature only cares whether our models make accurate predictions.

You can now close the thread.

Done.