Tracy writes:
> They would make EXCELLENT one-time encryption pads!

Yes.  Quantum Cryptography is a very active research area.

Not so much for use in *creating* ordinary one-time pads because, no matter
how you generate them, they have to be securely transported to the
receiver's location (and since the pads have to be the same size as the
message you're going to send, this usually raises the question of why not
just send the message itself).

The thing that Quantum effects let you do is to solve that key
*distribution* problem by letting you create an untappable communications
link.  By sending entangled photons through, say, a fiber optic cable, you
can detect whether or not anyone has looked at your message while it was in
transit.  It turns out that it's impossible to peek at the bits of the
message while they are in transit without the receiver being able to detect
that this happened.  You can use this, for example, to exchange a
cryptographic key by sending proposed key bits until enough have gotten
through without being spied upon.  If you send a number of bits equal to the
message you're going to send, then you can use it as a one-time pad to
encode your message and transmit it (at which point you don't care if the
bits get spied on, since they will be protected by the one-time key.

So you don't create a one-time pad with Quantum Cryptography, but Quantum
Cryptography can solve the problem of distributing a large volume of key
data securely thus allowing the one-time pad mechanism to be used in a
practical environment.

G.