4 ms·

right, "quantum teleportation" is a woefully misleading name, however this is still an impressive advancement and quantum teleportation will play a key role in

by aji 10y ago

right, "quantum teleportation" is a woefully misleading name, however this is still an impressive advancement and quantum teleportation will play a key role in wide-area quantum information networks

radicaldreamer 10y ago
This is probably also why SETI-like projects turn up nothing. It's likely that almost no advanced civilizations are using radio waves for communication.
- ethanbond 10y ago
  I'm only a layman who's mildly interested in this, but this contradicts my understanding... Someone correct me if I'm wrong here. You can't communicate with quantum teleportation. It sends random "information" (not information at all), because you can't control how the quantum waveform collapses. So you have to collapse the waveform, create a key that encodes your collapsed form to the information you want to transmit, and then transmit that key slower than light i.e. with radio. I guess you could argue that since the keys themselves are also indistinguishable from noise, we wouldn't detect slower-than-light key transmission either, though.
  - Dylan16807 10y ago
    Modern radio signals are pretty close to noise anyway. You increase capacity by going to the very limit of what your receiver can distinguish. The only thing you can measure from a distance is that certain frequency ranges have more power than background.
  - roywiggins 10y ago
    So far as I know, that's correct. There's even a handy theorem that states this pretty unequivocally! > it is not possible for one observer, by making a measurement of a subsystem of the total state, to communicate information to another observer. The theorem is important because, in quantum mechanics, quantum entanglement is an effect by which certain widely separated events can be correlated in ways that suggest the possibility of instantaneous communication. The no-communication theorem gives conditions under which such transfer of information between two observers is impossible. https://en.wikipedia.org/wiki/No-communication_theorem https://en.wikipedia.org/wiki/No-communication_theorem
  - aji 10y ago
    you can't "communicate", but it would be useful for qubits in one quantum computer to be sent to another quantum computer without physically moving the qubit. that was what I meant by wide-area quantum information networks
    - ethanbond 10y ago
      Oh totally agreed. My response wasn't to your comment, but to a comment implying that aliens are communicating "across" us but never through us via means of quantum teleportation and that's why can't detect them. I agree with you, this is impressive and probably will be very helpful some day.
      - radicaldreamer 10y ago
        Thank you! This is definitely one of those things where my understand was inaccurate and this thread has been immensely helpful to improve that.
elboru 10y ago
Since nobody has mentioned it, maybe I didn't understand the implications, but does this mean there is a chance in the future we won't have "bandwidth"? I could replicate data from a server into my personal computer instantly?
- TheRealPomax 10y ago
  Not really. Not unless you and whomever you were getting data from shared entangled particle pairs. While this is a real thing already, some banks use this setup for quantum encryption, it's probabilistic (particles can stop being entangled, so you have to run checks against a series of them and then decide that p>0.999 is good enough for instance) and the owners of each particle is regulated. There is no QT without first making sure two parties each hold half of an entangled pair, and then make sure they both use the same particle for running the QT algorithm against.
- aji 10y ago
  quantum teleportation is not instant, since the information about the particle's quantum state is still sent over a classical channel

by aji 10y ago

right, "quantum teleportation" is a woefully misleading name, however this is still an impressive advancement and quantum teleportation will play a key role in wide-area quantum information networks

radicaldreamer 10y ago

This is probably also why SETI-like projects turn up nothing. It's likely that almost no advanced civilizations are using radio waves for communication.

ethanbond 10y ago
I'm only a layman who's mildly interested in this, but this contradicts my understanding... Someone correct me if I'm wrong here. You can't communicate with quantum teleportation. It sends random "information" (not information at all), because you can't control how the quantum waveform collapses. So you have to collapse the waveform, create a key that encodes your collapsed form to the information you want to transmit, and then transmit that key slower than light i.e. with radio. I guess you could argue that since the keys themselves are also indistinguishable from noise, we wouldn't detect slower-than-light key transmission either, though.
- Dylan16807 10y ago
  Modern radio signals are pretty close to noise anyway. You increase capacity by going to the very limit of what your receiver can distinguish. The only thing you can measure from a distance is that certain frequency ranges have more power than background.
- roywiggins 10y ago
  So far as I know, that's correct. There's even a handy theorem that states this pretty unequivocally! > it is not possible for one observer, by making a measurement of a subsystem of the total state, to communicate information to another observer. The theorem is important because, in quantum mechanics, quantum entanglement is an effect by which certain widely separated events can be correlated in ways that suggest the possibility of instantaneous communication. The no-communication theorem gives conditions under which such transfer of information between two observers is impossible. https://en.wikipedia.org/wiki/No-communication_theorem https://en.wikipedia.org/wiki/No-communication_theorem
- aji 10y ago
  you can't "communicate", but it would be useful for qubits in one quantum computer to be sent to another quantum computer without physically moving the qubit. that was what I meant by wide-area quantum information networks
  - ethanbond 10y ago
    Oh totally agreed. My response wasn't to your comment, but to a comment implying that aliens are communicating "across" us but never through us via means of quantum teleportation and that's why can't detect them. I agree with you, this is impressive and probably will be very helpful some day.
    - radicaldreamer 10y ago
      Thank you! This is definitely one of those things where my understand was inaccurate and this thread has been immensely helpful to improve that.

elboru 10y ago

Since nobody has mentioned it, maybe I didn't understand the implications, but does this mean there is a chance in the future we won't have "bandwidth"? I could replicate data from a server into my personal computer instantly?

TheRealPomax 10y ago
Not really. Not unless you and whomever you were getting data from shared entangled particle pairs. While this is a real thing already, some banks use this setup for quantum encryption, it's probabilistic (particles can stop being entangled, so you have to run checks against a series of them and then decide that p>0.999 is good enough for instance) and the owners of each particle is regulated. There is no QT without first making sure two parties each hold half of an entangled pair, and then make sure they both use the same particle for running the QT algorithm against.
aji 10y ago
quantum teleportation is not instant, since the information about the particle's quantum state is still sent over a classical channel