I've played around with a device that uses quantum handwavium to link
two units. The link is very fast (might be instantaneous, might just
b e very FTL). They are addressable, and untraceable.

That is, when one is "tuned" to another, they "lock" and nobody else
can use that address until one of them goes offline. Adressses
involve a number of different parameters, all "stepwise". Potential
address are not infinite, but are very, very large.

Signal cannot be detected except by the other unit in the link. It is
not possible to determine the direct of the other unit. Signals can't
be jammed, unless you count deploying an insane number of units to
"use up" the address space.

Bandwidth is very high ("DC to daylight" :-)

So they are utterly secure, as long as you can be sure that neither
unit loses power.

That's both their greatest advantage and disadvantage. The good guys
don't have to worry about the bad guys intercepting transmissions.
But that also means the good guys can't intercept the bad guys
either.

Other folks have done similar things but with the transceivers made
in pairs and not adjustable.

That means you have to deliver one of a pair to whoever you want to
talk with.

the addressable version just means that they need a unit and the
"address". So they can change one for something else to one that
links to folks they aren't supposed to.

Either way destroys a lot of things we take for granted.

--
Leonard Erickson (aka shadow)
shadow at shadowgard dot com