Quantum Internet and Quantum Teleportation


#1

Wonder if Atlas has a hand in this :wink:


#2

Just to clarify, “Quantum teleportation” is not matter transport. It’s the application of a state from one particle to an entangled partner. The two entangled particles had to have been together at some point, so this doesn’t constitute superluminal communication either. Atlas seems to be way ahead in this field (well, no wonder, since they can get superlumina to send them research data from the future…).

Also, “Quantum internet” and stuff usually refers to using quantum entanglement for save encryption, as in Quantum key distribution, the actual data transfer is still handled by digital data.


#3

This is crazy… You just need to translate spins to binarie and you have instantaneous transluminal communication! Imagine the implications for space exploration! No “Interstellar” time-dilation crap to deal with!
Is this real? Are the lines crossing!?


#4

Not only space, deep ocean. Perhaps global connected computer systems acting as one. :wink:


#5

Unfortunately, that’s not how it works. First off, as mentioned above, the particles had to have been together at some point in time, so whatever distance they are apart had to be crossed at sublight speeds.
But while this would still be very neat, there’s an even bigger problem: You can’t know what you’re sending.
Quantum entanglement means that observation of one particle influences the other. Before observing, you don’t know what you have. Once you know, it’s already been “sent”. Hence, data transmitted by quantum entanglement is completely random. Which is great if what you want to share is an encryption key, but rather undesirable when you want to say hi.


#6

Thank you for clearing that up @jedidia because I was worried that we could soon have Quantum Flame Wars, Quantum Griefing, Quantum Doxing, and everything related to the Internet but in Quantum Quantities! -)

TQQdles™


#7

How about a constellation of micro-satellites pointing down?


Huge coincidence, right?


#8

If you are interested in the “No-communication theorem” this wikipedia page sums it up.


#9

The no-communication theorem implies the no-cloning theorem, which states that quantum states cannot be (perfectly) copied. That is, cloning is a sufficient condition for the communication of classical information to occur. To see this, suppose that quantum states could be cloned. Assume parts of a maximally entangled Bell state are distributed to Alice and Bob. Alice could send bits to Bob in the following way: If Alice wishes to transmit a “0”, she measures the spin of her electron in the z direction, collapsing Bob’s state to either {\displaystyle |z+\rangle _{B}} |z+\rangle _{B} or {\displaystyle |z-\rangle _{B}} |z-\rangle _{B}. To transmit “1”, Alice does nothing to her qubit. Bob creates many copies of his electron’s state, and measures the spin of each copy in the z direction. Bob will know that Alice has transmitted a “0” if all his measurements will produce the same result; otherwise, his measurements will have outcomes {\displaystyle |z+\rangle _{B}} |z+\rangle _{B} or {\displaystyle |z-\rangle _{B}} |z-\rangle _{B} with equal probability. This would allow Alice and Bob to communicate classical bits between each other (possibly across space-like separations, violating causality)

Ok, so cloning particles would be needed… Who would have guessed instantaneous quantum communication would be so counterintuitive! Pesky laws of physics…