Natural Science Forum / Physics / Particle Physics / January 2007

Hi Autymn,

Thanks for your reply.

I'm talking about the detection angle near Alice that communicates
itself across to the remote entangled particle near Bob, in the form of
a correlation violation. Certainly that detection angle is modulatable,
which means the correlation violation is modulatable. However, so far
we've not been able to detect the correlation violation without a
classical communication channel, in order to verify that there is
indeed a correlation violation occurring.

But now, if this Kerr microscopy method is as good as they say it is,
then that means you can pre-measure/pre-screen your entangled particles
without disturbing their entangled state. By using the Kerr method in
advance, you can pick through entangled pairs, selecting  only for
partners which are spin-Up, for example.

You take all the spin-Up entangled partners for yourself, and you give
all their spin-Down counterparts to your friend. Now you perform the
Bell's Inequality experiment, throwing your spin-Up particles in the
classical way at your detector, whose angle is controllable by you for
the purpose of encoding a signal.

Your friend will at the same time be measuring the entangled
counterparts he has at his end. Whenever his particles don't show as
spin-Down, then it means there's a correlation violation, which means
that you fiddled with the detector on your end in order to transmit an
information bit.

Again, I know that this whole scenario isn't supposed to be possible,
since you're not supposed to be able to pre-scan/pre-select what the
spin states are going to be. But that Kerr microscopy technique seems
to say that you can pre-measure stuff. So which is it? Can we
pre-measure or can we not?

I'd like to hear a more definitive answer on what David Awschalom and
the Santa Barbara group have done. Because it's being widely reported
that they have indeed accomplished pre-measurement (ie. measurement
which does not disturb the electron's state)

Comments?