Why quantum teleportation doesn't allow FTL communication

Bobby Martin (bobbymartin@hotmail.com)
Fri, 12 Dec 1997 22:34:31 PST


The receiver has an apparatus in which a number of entangled photons
are
captured. He measures these photons one by one, noting one of four
possible
values for these photons: A, B, C or D (these values represent the
polarization
of the photon.) He sees an apparently random assortment of values. He
knows that the teleportation is successful only 25% of the time, so he
doesn't
know which values are data and which are noise.

The sender attempts quantum teleportation on each of the entangled
photons
the receiver has. He is successful one time in four, and knows when he
is
successful. He notes when he is successful and the state of the photons
on these successes. He knows that the receiver has these values for
these
particular photons, but the receiver has no way of knowing that these
are
the values that represent meaningful data.

The sender can now send a slower than (or equal to) light speed message
to the receiver as to which values were successfully teleported, and
which
were noise. The sender can now read his message.

Note that the receiver's results will be the same whether the sender
attempts
teleportation or not: the receiver sees equally distributed random
values,
each value appearing 25% of the time. Some of those values may be
values
sent by the sender using quantum teleportation, but only the sender
knows.

Does that help any?

Bobby Martin

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