Re: A Question On Bell State Measurement.

[Robert B Zannelli <Spinoza321@AOL.COM>]

In a message dated 7/19/2003 9:14:38 AM Eastern Standard Time, jsd@AV8N.COM
writes:

> Usually the details of the production of the two
> photons are crucial.  You can't do it with just
> any two photons

I was trying to simply this question down to the bare minimum. However here
is a more complete description. This is difficult without diagrams. You create
entangled photon pairs by passing a photon through a parametric down converter
which generates two entangled photons in orthogonal states from each other,
Photon z and y.  Photon z is sent off to a distant measurement device. Photon y
is sent to the Bell State measurement device.
   This is also set up to create two reflected photons w and x, generated
from the same event which caused the parametric down conversion. Photon x is also
sent to the Bell Measurement device after it has been passed through a
polarizer which puts it in a particular state. The detection of photon w is a signal
that that photon z has been sent to a distant measurement device.
   Photons x and y meet at the Bell State measurement device and either
become entangled or don't. If they do then photon z has the same polarization state
as photon x after x is measured. Effectively x has been transported as photon
z.

Bob Zannelli