Re: Quantum challenge: How to distinguish H and V pol from diagonal mix - using long spatial separation of components

On Fri, 2 Jan 2009, Neil B. wrote:

There is a way in principle IMHO to distinguish H and V polarization
from diagonal mix - using spatial separation of components. I'm not
sure how practical it would be to find the difference, but it's worth
looking into and I believe this is an original proposal. I thought of
it some years ago but haven't put it out before.

H/V and the diagonal bases are just our artificially imposed descriptions. If it's valid to talk about what polarisation the photons "really" have, we should talk about left-circular and right-circular as the basis.

[cut]
That is enough to make a doubly peaked
photon that is very weird: the front end wave amplitude is actually
oriented along the x axis and the rear end, separated by an essentially
flat region, is actually oriented along the y axis.

Not a doubly-peaked photon, I'd say, but a doubly-peaked _wavefunction_ of a photon.

Why not separate the two polarisation components the easy way - just use a polarising beamsplitter. This gives a very clear separation of the two components into two separate beams, not just the front end and back end of a short pulse. Get a single-photon source, a detector in each polarisation channel, and count away. It might have been done already.

--
Timo Nieminen - http://www.physics.uq.edu.au/people/nieminen/
E-prints: http://espace.uq.edu.au/list/author_id/1189/
Spirits: http://www.users.bigpond.com/timo_nieminen/spirits.html
.

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