Double-Slit Experiment: Detection Without Destruction?

In summary, the Wiki article on the Double-slit experiment clarifies a common misunderstanding that adding a detector to determine the path of a photon will completely destroy the interference pattern. Instead, there are other methods of determining the path that may only partially affect the interference pattern. This is demonstrated in experiments using polarizers or atoms placed at the slits. The more certain we are about the path, the less interference will be observed. However, it is not an "all or nothing" situation and we have the choice to observe a percentage of wave or particle behavior, as long as it totals to 100%.
  • #1
eloheim
111
12
Hello guys I was a confused by this part of the Wiki article on "Double-slit experiment":

Wiki said:
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)??
 
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  • #2


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.
 
  • #3


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.
 
  • #4


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
 
  • #5


San K said:
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".
 
  • #6


DrChinese said:
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".
 
Last edited:

1. What is the double-slit experiment?

The double-slit experiment is a classic experiment in quantum mechanics that demonstrates the wave-particle duality of matter. It involves shining a beam of particles (such as electrons or photons) through two parallel slits and observing the resulting interference pattern on a screen.

2. How does the double-slit experiment demonstrate wave-particle duality?

The double-slit experiment shows that particles can behave as both waves and particles. When the particles pass through the slits, they create an interference pattern on the screen, similar to how waves interact with each other. This suggests that particles have both wave-like and particle-like properties.

3. What is meant by "detection without destruction" in the double-slit experiment?

"Detection without destruction" refers to the ability to observe the interference pattern of particles without disrupting their wave-like behavior. In traditional experiments, observing the particles would cause them to behave like particles and destroy the interference pattern. However, in the double-slit experiment, researchers have found ways to observe the particles without disrupting their wave-like behavior.

4. What are some real-world applications of the double-slit experiment?

The double-slit experiment has implications for various technologies, such as quantum computing and cryptography. It also has been used to study the behavior of particles in different environments and to better understand the fundamental principles of quantum mechanics.

5. Are there any controversies surrounding the double-slit experiment?

There have been debates and controversies surrounding the interpretation of the double-slit experiment and its implications for the nature of reality. Some scientists argue that the experiment supports the idea of a multiverse, while others believe it can be explained by other theories. However, the experiment itself and its results are widely accepted in the scientific community.

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