Storing Bandwidth with Quantum Teleportation

strilanc.com

17 points·Strilanc··4 comments

Well, that's a viable commentary on a possible communication channel. Much more than what I was expecting. But the one thing that it does not do is store bandwidth, that's a bad title.

It does store "bandwidth" specifically of the quantum channel, and only because there is no information going through it.

Anyway, the idea of storing qbits is quite interesting, but I don't think even that would make quantum cryptography useful.

Author should comment on the difficulty of performing a bell-state measurement.

(Author here)

Do you have a link? I don't know much about the engineering details, other than "It's hard. Every part of it is hard.".

Is it the controlled not that's tricky?

A bell-state measurement is the holy grail of QKD. It can only be done 25% of the time and with great difficulty 50% of the time. So your channel only works 25% of the time!

For entanglement in a single qubit variable, only three distinct classes out of four Bell states are distinguishable using such linear optical techniques. This means two Bell states cannot be distinguished from each other, limiting the efficiency of quantum communication protocols such as teleportation. If a Bell state is measured from this ambiguous class, the teleportation event fails. >>http://en.wikipedia.org/wiki/Bell_state#Bell_state_measureme...

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