B Is this equal to teleporting information?

[TJung]

http://m.phys.org/news/2016-09-quantum-internet-teleport-particle-kilometres.html

Is it possible to teleport information?

 

[secur]

Yes, quantum "teleportation" does transmit information. The speed of transmission is <= c (light speed), so doesn't violate relativity - of course.

 

[Strilanc]

Quantum teleportation is a thing, but it's probably not what you're picturing in your head. It's more like...

Alice and Bob share an entangled EPR pair $S$; qubits in a special state where they agree along the Z axis and also they agree along the X axis.
Alice wants to send a qubit $M$ to Bob.
Alice compares $M$ to $S_A$ along the X axis, getting a SAME_X or OPPOSITE_X result.
Alice also compares $M$ to $S_A$ along the Z axis, getting a SAME_Z or OPPOSITE_Z result.
Alice's results tell her how Bob's $S_B$ relate to $M$.
For any OPPOSITE results, Alice tells Bob he needs to flip over $S_B$ to fix the problem.
Then she tells him he's good to go, $S_B$ is now SAME as $M$ was along both the X and Z axes.
$M$ has been moved into $S_B$.

It's exactly analogous to a classical one-time pad. Instead of sending the information directly, you say how the information relates to a shared secret.

 

[rootone]

Is it possible to teleport information?

Yes, you just did that by asking the question on the internet.

 

[TJung]

Yes, you just did that by asking the question on the internet.

I mean, is there FTL information transfer?

 

[Carrock]

I mean, is there FTL information transfer?

No. See https://www.physicsforums.com/threads/is-this-equal-to-teleporting-information.890166/#post-5599762

 

[TJung]

Yes, quantum "teleportation" does transmit information. The speed of transmission is <= c (light speed), so doesn't violate relativity - of course.

So what exactly is being teleported? I understand teleportation as the instantaneous transfer of something, so FTL.

 

[maxverywell]

No you cannot teleport (FTL) information or energy or matter.
In quantum teleportation schemes they "teleport" a quantum state $\psi$, but a classical channel of communication is always needed in order to complete the teleportation (so the information is not sent FTL, but at the speed of light). Otherwise, the receiver can only hope that he will get the state $\psi$ on his system and not some other state. With the classically sent additional information, the probability that the receiver will get $\psi$ can become 1.

 

[TJung]

No you cannot teleport (FTL) information or energy or matter.
In quantum teleportation schemes they "teleport" a quantum state $\psi$, but a classical channel of communication is always needed in order to complete the teleportation (so the information is not sent FTL, but at the speed of light). Otherwise, the receiver can only hope that he will get the state $\psi$ on his system and not some other state. With the classically sent additional information, the probability that the receiver will get $\psi$ can become 1.

So when they talk about quantum internet, its about security, not speed?

 

[Nugatory]

So when they talk about quantum internet, its about security, not speed?

Yes. Google for "quantum key distribution".

 

[Strilanc]

So when they talk about quantum internet, its about security, not speed?

It's also about flexibility and historically-surprising facts.