Young's Expt.

[ianlamb at ihug.co.nz]

At the Writers and Readers Festival in Auckland I was interested to learn
from Marcus Chown that Young's experiment had been done with a single
photon. This got me thinking (quite painful at my age) and maybe someone
can lighten my state of darkness.

As I recall, the experiment was originally done by cutting slits in black
material. With a stream of photons you get an interference pattern on the
other side.  

If the slits were cut into a reflecting surface instead of a black one and
it was bent into a gentle parabola and angled so that the focus was not in
the path of the stream of emitted photons, I would expect the focal point
to be a detectable bright spot. There should also be the usual pattern on
the other side of the slits.

My question is: what would happen if there was a single photon emitted
towards the slits? Would it appear at the focal point because it behaved
like a wave at the reflecting surface? Would it appear at the focus because
it had been reflected as a particle from the surface between the slits?
Would there be an interference pattern on the other side of the slits? If
light didn't appear at the focus, why not? Why would it be transmitted
rather than reflected? Or would it be reflected rather than transmitted? If
it is both reflected and transmitted, what does that mean? Would the energy
of the photon have been divided? Would it's frequency be different at both
locations as a result?

The implications are a bit large for my simple mind to deal with but it
seems logical as the original experiment doesn't preclude using a
reflective surface, it's just that Young used a black one.

Has this experiment been done?

Ian Lambert