B Questions about double slit experiments

[Nugatory]

Is that what is meant when we say the electron is in a superposition?

No. Superposition refers to a mathematical property of the wave function, namely that any wave function can be written as the sum of other wave functions.

May I ask when calculating the probability of a single electron being detected are both slits included in the calculation?

From #23 of this thread: “we add the amplitudes of the waves arriving from all open points in the barrier”. That means “all open points” whether these points are all in one slit or in multiple slits.

You may have been confused by the way that elementary and non-serious explanations treat the double-slit case as something somehow fundamentally different from the single slit case. It’s not, it’s just the easiest example of interference. What’s going on here is that if two openings are small compared with the wavelength of the incident beam, and if they are separated by a distance that is large compared with that wavelength but are still close enough together to both be illuminated by the beam... then to very good approximation we can say that there are just two points and two amplitudes, one from each point, to add - @PeroK showed you that calculation in post #10.
But if these conditions do not hold, then the calculation requires adding the amplitudes from each point; there are an infinite number of points in any non-zero area no matter how small so we end up having to do a seriously non-trivial integration across the area of all the openings (one slit, two slits, twenty-three slits, the holes left by a volley of machine-gun fire, ...) in the barrier.
No pop-sci treatment is going to inflict this integral on the audience when a “just add two things” example is an option, so we miss out on the general principle. The introductory QM course for an undergraduate physics major is a different matter; we don’t start that until after we’ve spent an entire semester with something like this so we that we can do the general calculation for any configuration of the barrier.

maybe it’s just my use of words or classical thinking. Can’t help but think if the slits effect the outcome then there is something going on with the electron and the slits, even if we don’t need to know what that is to calculate the probability of an electron being detected at a certain point on the screen. Not important for QM of course but can’t help but wonder what it could be. :)

That’s classical thinking. We’re using the classical idea that a particle can’t be at A and later at B without having been somewhere in between; without that assumption there’s no reason to think that the particle was ever anywhere near the barrier and slits.

 

[DennisN]

Isn't that diffraction pattern caused by the 'wave' bending around a slit or opening and not the same as the interference pattern which is caused by two or more waves interacting?

Google for “single slit diffraction pattern” to find images of the pattern formed on the screen.

Hi, @rede96 , I posted such an image in this post.

 

[BvU]

Well if all one had to do to understand QM was watch a Feynman lecture and make a few posts on PF we’d all be experts in no time. So rather than be critical of my lack of understanding maybe you could try and help by detailing specifically just what about my reply (I’ve reposted below)I’m missing.
...
Not sure what you mean by that?
...
Again not sure what you mean by that? Can you clarify by detailing what assumptions I seem to have made in my posts that are incorrect please. It’ll help me understand where I’m going wrong.

My apologies - the post isn't really helpful and inspired more by exasperation and despondency than by ideas on how to get you on the right path.

The difficulty here is that you want to know answers to questions that shouldn't be asked (such as through which slit what fraction passed, the 'role' of the slit(s) and similar issues). Easy to say, even for non-experts like me. But there is admittedly a very difficult transition from the marble bridge to $\lambda$ scale phenomena, and human curiosity is naturally reluctant wrt the required changes in perception.

The frequent reference to Feynman is because he's so good at helping to bridge the gap. He gives a layman lecture on photon behaviour and then says "they're particles". Another often quoted phrase is "shut up and calculate".

You've been given quite a bit of very good help in this thread, especially from @Nugatory , whose patience I really admire, and I suggest you re-read the stuff and the links and references to get the right taste for further questions !

Perhaps we can find some relief in the parallel between QM and thermodynamics: If you think you understand it, you don't By the way: single slit, double slit -- it's all one and the same thing: wave behaviour

$\$

 

[PeroK]

By the way: single slit, double slit -- it's all one and the same thing: wave behaviour

You mean "particle behaviour"?