Hi Syamsu,
I may need help from people knowledgeable about quantum theory before making a decision on this one. I can't tell if the Wikipedia article on the
Elitzur-Vaidman bomb-tester makes legitimate use of quantum theory, is highly speculative, or is completely bogus.
So let me describe what appears to me to be a contradiction and see if we can resolve it to give me more confidence in the article. First, here's their diagram:
The B in the red explosion is a bomb that is either a real bomb or a dud, and the text tells us that what is represented by the B is a mirror attached to a plunger which is attached to the bomb's detonator:
Now consider a slight variation: a mirror attached to a plunger, which is attached to the detonator.
And the text says that when a photon strikes the mirror it pushes the plunger and detonates the bomb:
A photon that impinges on the mirror pushes the plunger and this detonates the bomb.
The text goes on to say that a dud is one whose plunger is stuck, so that when a photon hits the bomb's mirror, the plunger doesn't move and the bomb doesn't explode. Photons are reflected from the mirrors of dud bombs:
The duds are those bombs whose "plunger" is stuck, so that even if a photon hits the mirror, the plunger does not get pushed, and no detonation occurs. This property is important, because it means a dud effectively just reflects the photon.
Now here's where things go awry. Further on in the text under the heading "
If the bomb is a dud" it says that a dud bomb will not absorb the photon and that therefore the bottom horizontal path is a possible route to the detectors at C and D:
The bomb will not absorb a photon, and so the lower route is a possible path to the point of interference.
But the bomb's mirror is supposed to reflect the photon, presumably back to A, not transmit it.
This tells me that the diagram is misdrawn. The bomb B is not actually an element midway between the lower two mirrors. Rather, the lower right hand mirror is the bomb's mirror, and the B should be moved over to the right of it outside the path between the lower two mirrors. In other words, the diagram should look like this:
And what the text is telling us is that a good bomb's mirror absorbs the photon and explodes. In other words, the good bomb acts as an observer. A dud bomb reflects the photon up to the detectors at C and D.
Another less convoluted formulation is that this is a way of telling whether the mirror in the lower right hand corner is actually a mirror or a detector. The device can purportedly tell you when it is a detector without ever setting off the detector.
Cavediver, Son Goku or anyone else knowledgeable about quantum theory, if you care to comment about this analysis please post to
Topic Proposal Issues.
Edited by Admin, : Fix link.
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