Double-Slit Experiment: Detection Without Destruction?

[eloheim]

Hello guys I was a confused by this part of the Wiki article on "Double-slit experiment":

It is a widespread misunderstanding that, when two slits are open but a detector is added to the experiment to determine which slit a photon has passed through, then the interference pattern no longer forms and the experimental apparatus yields two simple patterns, one from each slit, superposed without interference[12][citation needed]. Such a result would be obtained only if the results of two experiments were superposed in which either one or the other slit is closed. However, there are many other methods to determine whether a photon passed through a slit, for instance by placing an atom at the position of each slit and monitoring whether one of these atoms is influenced by a photon passing it. In general, in such experiments, the interference pattern will be changed but not be completely wiped out. Interesting experiments of this latter kind have been performed with photons[9] and with neutrons.

It seems like all the (popular physics) accounts I'm familiar with go out of their way to endorse exactly the point in question. Is the author of the wiki article trying to impress that "detection" is not an all-or-nothing proposition, and therefore the act of it doesn't neccesarily destroy the interference pattern (as in completely)??

 

[Bill_K]

I'd like more information. I can't think of any way a photon can "influence an atom" and then go on to hit the same spot on the screen.

 

[DrChinese]

One of the partial techniques is to use polarizers aligned relative to each other. As you vary from parallel to crossed, the inteference pattern changes from full interference to no interference.

 

[San K]

in the experiment above (with atom)...is the which-way information with 100% certainty?

i.e.

can we thus say this:

the higher the "probability of knowing which-way information" the lesser the degree of intereference

or

when we try to be more certain of which-way info, we end up reducing the interference pattern

or

you cannot know both the path and have interference at the same time

or

the more certain you are about the path, the lesser the interference on the screen

 

[DrChinese]

in the experiment above (with atom)...is the which-way information with 100% certainty?

i.e.

can we thus say this:

the higher the "probability of knowing which-way information" the lesser the degree of intereference

or

when we try to be more certain of which-way info, we end up reducing the interference pattern

or

you cannot know both the path and have interference at the same time

or

the more certain you are about the path, the lesser the interference on the screen

Yes, the more certain you are of the path, the less interference. It is not "all or nothing".

 

[San K]

Yes, the more certain you are of the path, the less interference. It is not "all or nothing".

thanks Dr Chinese, can we say that we have the choice to observe the percentage of wave vs particle behavior?...however the percentage "must total to 100".