Quantum Mechanics?

Question

In the double slit experiment we observe interference pattern when two slits are used and no detector is present at slits , now when the electron gun fires at a very slow rate suppose 1 elec/30 min then also we observe interference pattern , now we wish to see that elec is going through which slit so we place a detector with a very high resolution at one slit then we do not observe the interference pattern , suppose the resolution is made as low as possible as half width of slits then will we observe intereference pattern or not ? If we do not then the contradiction is that we should observe the interference pattern but we are not , am i right ?

Answer 1

I assume your questioning the uncertainty principle of quantum mechanics. I had to read it several times but I think I see where you are getting at. If you cut the resolution down you still would not see an interference pattern, as you predicted.

I on the other hand can't agree with the fact that this contradicts the uncertainty principle. It is my belief, and I can't necessarily prove it, that cutting the resolution on the detector doesn't change the fact that you are still recording the location of a particles position in space and thus destroying the interference pattern.

Of course the only way someone could tell you a sure fire answer would be to test this on there own and try various alternatives with particle detectors. I'm sure, while creative, your probably not the first person to think of this and I'd be willing to bet that tests and experiments have been run. I still would think though that regardless of resolution on detectors, you still would destroy your interference pattern.

Answer 2

If you make a measurement at one of the slits, it collapses the wave function of the electrons so they never have a chance to interfere beyond the slits. Resolution doesn't matter - you have made an observation, which by definition, collapses the wave function of the electrons. By making an observation, you are sampling the probability distribution which alters the experiment. Thus, you can't expect to get the interference pattern.

Answer 3

As the resolution at the slits gets more accurate, the interference pattern gets more smeared out. When the resolution is enough to distinguish between the two slits, the interference pattern is smeared to the point that it is mostly gone.