Experimental interference of independent photons

[ZapperZ]

Don't miss this paper from the Zeilinger group:

R. Kaltenbaek et al, PRL 96, 240502 (2006).

In particular, read the first paragraph:

Is it possible to observe fully destructive interference of photons if they all originate from separate, independent sources? Yes, according to quantum theory. The perfect interference of photons emerging from independent sources cannot be understood by the classical concept of the superposition of electromagnetic fields but only by the interference of probability amplitudes of multiparticle detection events. As stressed by Mandel ‘‘this prediction has no classical analogue, and its confirmation would represent an interesting test of the quantum theory of the electromagnetic field’’

Zz.

[RandallB]

‘‘this prediction has no classical analogue, ....."Don’t see how this can be claimed.
A simple classical pool of water with two points independently generating waves of exactly the same frequency will generate waves that overlap each other and can be observed alone a line some distance from both sources. Even if the sources are out of phase that phase difference between the independent sources would remain fixed as the frequencies are the same. You would still find points along the observation line of complete constructive interference with the waves doubling in size. And points in-between those constructive points where there is destructive interference and no wave or change in water height at all. How much more of a matching classical analog could they expect? I see no interesting test here that would indicate anything.

[ZapperZ]

Don’t see how this can be claimed.
A simple classical pool of water with two points independently generating waves of exactly the same frequency will generate waves that overlap each other and can be observed alone a line some distance from both sources. Even if the sources are out of phase that phase difference between the independent sources would remain fixed as the frequencies are the same. You would still find points along the observation line of complete constructive interference with the waves doubling in size. And points in-between those constructive points where there is destructive interference and no wave or change in water height at all. How much more of a matching classical analog could they expect? I see no interesting test here that would indicate anything.

Read the paper. If you can show mathematically how classical wave superposition can produce the same results shown in Fig. 3, then write to PRL.

Zz.

[Hans de Vries]

You can read the paper here:

http://arxiv.org/abs/quant-ph/0603048


For those who want to find interpretations of Quantum Mechanics in
combination with Classical EM:

If one photon enters the beamsplitter it will be detected only at one
of the two outputs, either one but not at both outputs at the same time.


In this experiment:

If two equal photons enter the beamsplitter at the same time, at
different inputs, (there are two inputs), there will only be something
detected at one of the two outputs, either one, but there won't be
detected anything at both outputs at the same time.

This is the so-called Hong-Ou-Mandel-type (HOM) interference.
The effect disappears if the two photons have different polarization.


Regards, Hans