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εllipse
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Can two photons interfere with each other, or is interference strictly limited to a photon (et cetera) "interfering with itself"?
εllipse said:Can two photons interfere with each other,
Edgardo said:@Marlon:
Diffraction can be explained by single photon interference, it's not a result of two photons interacting with each other (see example above).
Edgardo said:unlike the previous two posters, I have another opinion. Photons do not interfere with each other.
Hmm, I don't really know; I'm confused on this, so that's why I'm asking .Edgardo said:But let's ask εllipse what exactly he means with his question.
εllipse said:In my physics class, my teacher teacher mentioned a little about the wave properties of light, and I assumed it was similar to how two out of phase sound waves can have destructive interference
εllipse said:, but in reading about quantum mechanics I've learned that the wave properties of photons, and everything else, are waves or probablity, and then you have the Feynman interpretation, where one particle takes all paths and "interferes with itself"; is that right?
εllipse said:So I was asking if two particles will interfere with each other or if the interference is limitted to one particle interfering with itself. Maybe I don't know enough of what I'm talking about to ask the question right.
εllipse said:Let me try asking another way, and hopefully it'll make sense. Can two light waves which are out of phase destructively interfere and produce no light? And is this a different question from asking, "Can two photons which are out of phase destructively interfere and produce no photons?"
εllipse said:Why is quantum mechanics so much more difficult for me to get a handle on than relativity?
Yes.εllipse said:Can two light waves which are out of phase destructively interfere and produce no light?
Yes.εllipse said:And is this a different question from asking, "Can two photons which are out of phase destructively interfere and produce no photons?"
It's probably the more difficult for everyone. There's just moreεllipse said:Why is quantum mechanics so much more difficult for me to get a handle on than relativity?
12th (US)Edgardo said:I'd like to know in which grade you are, then we know how far we can go with our explanations.
Ok, so what you're saying is although this can model reality, it's not at all what really happens. And I know physicists shy away from saying what does "really" happen, but there are times when you can say there are certain things that obviously don't "really" happen (like the Bell inequality, which puts a restricts certain ways the world can't be (local realism, etc)). So two sources of light won't interfere with each other in the sense of destructive interference and wave patterns? The Michelson-Morely experiment stuff I've read has talked about it as if two photons interfere with each other, but I am assuming that in the context of the quantum mechanics, what's really happening is an individual photon is traveling both paths and interfering with itself?Yes, that's correct. If you don't use quantum mechanics, then you can compare the wave properties of light with that of sound waves. And there's nothing wrong with this model, it's a wonderful theory which allows you to calculate the pattern behind a double slit, single slit etc..
It only becomes a problem when you turn down the laser intensity and you see single photons behind the double slit:
http://www.colorado.edu/physics/2000/schroedinger/two-slit2.html
http://www.colorado.edu/physics/2000/schroedinger/two-slit3.html
Yes, I think so. I know about the double slit experiment and have read that it has been performed by sending single particles through at a time, so the conclusion is that there is some way the particles take both paths, because when they end up on the other side it's just a dot, although statistically it makes an interference pattern as more and more dots build up.And a question to you: Do you know the double slit experiment, and what problem comes up when you see single photon dots on the screen?
This experiment really helped me to understand what is meant by "the photon interferes with itself".
Do you mean that two probability waves from the same photon which go through different slits in the double slit experiment will ineterfere, or are you saying that two "light waves" of some other meaning from different sources can interfere?Sherlock said:Yes.εllipse said:Can two light waves which are out of phase destructively interfere and produce no light?
In my opinion what "really" happens is that single photons interfere with themselves.ellipse said:Ok, so what you're saying is although this can model reality, it's not at all what really happens.
What you probably read two electromagnetic waves interfering, NOT two photons interfering with each other. You can use the wave model too.ellipse said:The Michelson-Morely experiment stuff I've read has talked about it as if two photons interfere with each other, but I am assuming that in the context of the quantum mechanics, what's really happening is an individual photon is traveling both paths and interfering with itself?
I am a little careful here. I did a little search on the internet and read about an experiment where you have two independent(!) laser beams that show "some sort of" interference effect. I can't tell you what kind of interference exactly was observed in the experiment (I think beat signal), since I haven't read the papers yet [1],[2],[3] (see at the bottom of this post).ellipse said:So two sources of light won't interfere with each other in the sense of destructive interference and wave patterns?
[PLAIN said:http://www.physicstoday.org/pt/vol-54/iss-8/p62.html][/PLAIN]
Pursuing the theme of fourth-order interference with pairs of photons in the late 1980s, Mandel and his students demonstrated quantum spatial beating, violations of local realism, and phase memory due to quantum entanglement with the vacuum. His group showed that P. A. M. Dirac's well-known statement about single-photon interference must be modified to assert that, in fourth-order interference, a pair of photons interferes only with the pair itself. He and his students also introduced what became known as the Hong-Ou- Mandel interferometer.
"Quantum effects in one-photon and two-photon interference" said:It should be clear from the foregoing that in these experiments one photon does not interfere with another one; only the two probability amplitudes of the same photon interfere with each other. This has been confirmed more explicitly in interference experiments with a single photon (Grangier et al., 1986) and in experiments with two independent laser beams, in which interference was observed even when then light was so weak that one photon passed through the interferometer and was absorbed by the detector
long before the next photon came along (Pfleegor and Mandel, 1967, 1968).
εllipse said:Do you mean that two probability waves from the same photon which go through different slits in the double slit experiment will ineterfere, or are you saying that two "light waves" of some other meaning from different sources can interfere?
Yes, two photons can interfere with each other as they are both electromagnetic waves and can exhibit wave-like behavior, including interference.
Interference between photons is when two or more photons interact with each other and their combined wave patterns either amplify or cancel each other out, resulting in a different overall intensity or direction of the light.
Photons can interfere with each other through two main mechanisms: constructive interference, where the waves align and amplify each other, and destructive interference, where the waves cancel each other out.
Yes, photons can interfere with each other in vacuum as they do not require a medium to propagate and can still exhibit wave-like behavior. However, the phenomenon of interference may be more noticeable in a medium such as air or water due to the interaction of the photons with the medium.
The interference of photons plays a crucial role in various phenomena, such as the creation of patterns in Young's double-slit experiment, the functioning of optical devices like interferometers, and the behavior of light in diffraction and holography. It also helps us understand the wave-particle duality of light and its fundamental nature in the universe.