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Does this question make sense in the quantum world?

Imagining a single photon (wave packet?) interacting with a single atom (its electrons etc) how do we currently describe/define the emitted photon in terms of its direction in relation to the incoming photon?

Now "scaling up" to a surface of atoms actually reflecting "light" according to the simple reflection rules like angle-in equals angle-out how do we manage to explain this effect in terms of the quantum world? How comes the probabilities work out for the out-going angle depending on the incoming-angle?

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Just remember that energy, momentum and angular momentum have to be conserved and you will get a spatial probability distribution. Of course, you have to take into account the recoil velocity of the atom as well. – Antillar Maximus Mar 9 '12 at 0:47
I can only add this links Emergence of a measurement basis in atom-photon scattering, Y. Glickman, S. Kotler, N. Akerman and R. Ozeri, Science, 339, 1187 (2013) Reversal of photon scattering errors in atomic qubits, N. Akerman, S. Kotler, Y. Glickman and R. Ozeri, Phys. Rev. Lett. 109, 103601 (2012) I get there from… – tyoc213 Feb 19 at 19:07

1 Answer 1

Not a full answer, but remember that any issue with path of particle must be done with a sum-over-paths (think it's called a Feynman integral) approach. I don't even think that $\angle i=\angle r$ is necessary for a single photon; it's only when we get multiple photons that interesting things happen.

You may want to see this

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