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From the article: Teleportation can also securely transmit quantum information even when Alice does not know where Bob is. Bob can take his entangled particle

From the article: Teleportation can also securely transmit quantum information even when Alice does not know where Bob is. Bob can take his entangled particle wherever he pleases, and Alice can broadcast her instructions for how to ungarble the teleported state over whatever conventional channels — radio waves, the Internet — she pleases. That information would be useless to an eavesdropper without an entangled link to Alice.

JeremyBanks 14y ago
As far as I can tell, this just seems like an obscenely overcomplicated one time pad. Instead of Alice giving Bob a string of bits that are known in advance, she gives Bob an entangled particle that can be collapsed to determine a string of bits at a later date. I can't see any security benefit. This is very neat from a purely scientific perspective. It seems pointless and misleading to try to present it as having direct practical value.
- BerislavLopac 14y ago
  This is very neat from a purely scientific perspective. It seems pointless and misleading to try to present it as having direct practical value. If I had a buck for every time this was said about a scientific discovery, I would be quite well off...
- jvdongen 14y ago
  For one thing, AFAIK, Alice can be sure that Bob's 'pad' is the only copy in existence because no one can copy Bob's 'pad' without destroying the entanglement. For a 'regular' one time pad this is not the case. Someone could have copied it and both Alice and Bob would be none the wiser until it's too late. One-time pad based encryption schemes are theoretically unbreakable - one of the things (the thing?) holding back wide spread adoption is the difficulty of proper key management. This has the potential to solve that issue.
- gus_massa 14y ago
  The difference is that the quantum version of the "one time pad" can't be copied. So if someone stole Bob's quantum states he would realize. (Anyway for practical applications this is still overcomplicated and http://xkcd.com/538/ http://xkcd.com/538/ apply.)
- Symmetry 14y ago
  Basically, the advantage is that you're creating the same one time pad in two faraway places at the same time, so there's no risk of it being intercepted. If Eve tries to mess with the stream of entangled photons all that will happen is that Alice and Bob will see garbage when they try to decrypt their message. If the one-time pad had been sent via traditional means, Eve would be able to read the message without Alice and Bob knowing.
sukuriant 14y ago
So a VERY advanced version of this could be used for things like: * underground/underwater communication systems where wires and radio waves faulter * interstellar communication without antennae and without bouncing the signal off satellites * radiowave-less espionage * etc?
- astrodust 14y ago
  Maybe even something crazy like teleportation!

JeremyBanks 14y ago

As far as I can tell, this just seems like an obscenely overcomplicated one time pad. Instead of Alice giving Bob a string of bits that are known in advance, she gives Bob an entangled particle that can be collapsed to determine a string of bits at a later date. I can't see any security benefit. This is very neat from a purely scientific perspective. It seems pointless and misleading to try to present it as having direct practical value.

BerislavLopac 14y ago
This is very neat from a purely scientific perspective. It seems pointless and misleading to try to present it as having direct practical value. If I had a buck for every time this was said about a scientific discovery, I would be quite well off...
jvdongen 14y ago
For one thing, AFAIK, Alice can be sure that Bob's 'pad' is the only copy in existence because no one can copy Bob's 'pad' without destroying the entanglement. For a 'regular' one time pad this is not the case. Someone could have copied it and both Alice and Bob would be none the wiser until it's too late. One-time pad based encryption schemes are theoretically unbreakable - one of the things (the thing?) holding back wide spread adoption is the difficulty of proper key management. This has the potential to solve that issue.
gus_massa 14y ago
The difference is that the quantum version of the "one time pad" can't be copied. So if someone stole Bob's quantum states he would realize. (Anyway for practical applications this is still overcomplicated and http://xkcd.com/538/ http://xkcd.com/538/ apply.)
Symmetry 14y ago
Basically, the advantage is that you're creating the same one time pad in two faraway places at the same time, so there's no risk of it being intercepted. If Eve tries to mess with the stream of entangled photons all that will happen is that Alice and Bob will see garbage when they try to decrypt their message. If the one-time pad had been sent via traditional means, Eve would be able to read the message without Alice and Bob knowing.

sukuriant 14y ago

So a VERY advanced version of this could be used for things like: * underground/underwater communication systems where wires and radio waves faulter * interstellar communication without antennae and without bouncing the signal off satellites * radiowave-less espionage * etc?

astrodust 14y ago
Maybe even something crazy like teleportation!