PHYS; Quantum Teleportation

John K Clark (
Fri, 12 Dec 1997 10:11:44 -0800 (PST)


On Fri, 12 Dec 1997 Dan Fabulich <> Wrote:

>>In a way you could say that I did send him a message faster than
>>light, but it was encrypted and can only be read when I send him
>>the key at light speed or less.

>This still seems like I could communicate with you FTL if *I had
>already sent you the key* and from there you're just interpreting it.
>Again, suppose I tell you (subluminally) that property (polarization?
>luck?) X means 0 and property Y means 1, and THEN we separate.

Something like that is already being done, 2 banks in Switzerland used it to
transfer information across Lake Geneva, not because it's faster but because
it's absolutely secure. It's no faster than light because I can't send you
the key until I know what the message I want to send you is, the key depends
on the message, and if I already know the message before we separate then I
might as well just hand it to you and forget about the key and all this
quantum business.

Nevertheless this could turn out to be very useful, in building quantum
computers for example, and if anybody does that then Quantum Cryptography
would be the only form of Cryptography that still worked.

John K Clark

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