Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

I have a very basic question about photons in double-slit experiment. I am not good at math, and have some Quantum mechanics knowledge. Math free explanation would be very good to me.

When we do double slit experiment with single photon at a time, it will be detected at some location of screen. Over the time period the accumulation of detected locations show interference pattern. The reason for the interference pattern is that photon's location in not well defined, the presence of photon in particular place can be determined by prbability and this probability is presented as a wave. that probability wave is splitted in to two while passing the two slits, collide with each other and causes interference pattern.

Question 1: Is this reason for single photon interference correct?

Question 2: How is the probability wave behaving while two-photons passing double-slit at a time? Are 4 probability waves (2 for each) interfering?

share|improve this question
    
'location [...] is a probability' ???? –  Danu Jan 31 at 2:57
    
I have improved my question. please check now. –  Vijayan Jan 31 at 5:25

1 Answer 1

Question 1: Is this reason for single photon interference correct?

The most intuitive way of looking at interference that I have encountered is Feynmann's Path Integral Formulation. Loosely speaking, if you have a photon (or anything, really) in location A and want to work out its chance of moving to B, you imagine it taking every possible path between the two at the same time. All of these paths interfere with each other resulting in some final amplitude from which you can extract the probability of the particle moving from from A to B. This sounds kind of like what you were trying to say when you said that the 'probability wave is split in to two'. All particles do this when moving, not just photons, however in the classical (i.e. large) limit, you can show mathematically that only one particular path will contribute to the particle's motion, which is why when you throw a tennis ball across the room you don't see it taking every possible path at once.

Question 2: How is the probability wave behaving while two-photons passing double-slit at a time? Are 4 probability waves (2 for each) interfering?

For a double slit experiment, the interference pattern does not change with light intensity. I believe you can think of each photon as behaving independently in this case.

share|improve this answer
    
Fine. somehow I got answer. let me confirm it. two photons are travelling independent path to each other, and not colliding with each other. –  Vijayan Jan 31 at 16:12
    
Yes, we generally think of photons as interfering rather than colliding. It is like if two waves of water 'impact', they just travel through each other. –  Andrew Ledesma Jan 31 at 23:48

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.