Earlier quoted context omitted.
No, while entanglement acts instantaneously across a large distance, there's no way for that "signal" to carry any information. In order to complete the teleportation the two parties must somehow communicate in order to convey an additional piece of information. This communication would be classical and slower than light.
This reveals my severe ignorance about quantum mechanics; but I've always wondered if entanglement could be used to transmit binary data by way of timing and presence or lack of presence of a transmission. So maybe every 1ms is a position, and either something is sent or not.
Sustained, high-fidelity quantum teleportation
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Re: Sustained, high-fidelity quantum teleportation
#32Earlier quoted context omitted.
Yes and no. Yes, information can travel with infinite speed. No, cause-effect relationship cannot travel faster than light. https://en.wikipedia.org/wiki/Quantum_nonlocality
> Yes and no. Could a QM answer be otherwise?
Re: Sustained, high-fidelity quantum teleportation
#33Earlier quoted context omitted.
This makes zero sense. If the information must be conveyed classically anyway, what's the point?
Physical qubits are much more sensitive to transmission noise than physical bits. If you want to transmit qubits, teleportation allows you to do it with higher fidelity than by physical transmission. Why do you want to transmit qubits? For various emerging quantum information technologies, each with different potential economic impact.
Re: Sustained, high-fidelity quantum teleportation
#34context: Using term teleportation makes sense in the quantum realm. No-cloning theorem in quantum physics says that it's impossible to do exact copy of unknown quantum state. But it turns out that you can teleport it when the original state is destroyed. You can't have exact `cp` command for the quantum state, only `mv`. If this makes you think linear logic, you are right.
Ie if you teleport and the original isn’t destroyed. Which one are you?
Re: Sustained, high-fidelity quantum teleportation
#35Earlier quoted context omitted.
This makes zero sense. If the information must be conveyed classically anyway, what's the point?
It clearly makes no practical sense at the moment outside of research.
https://directory.eoportal.org/web/eoportal/satellite-missio...
https://spectrum.ieee.org/tech-talk/computing/networks/quant...
Re: Sustained, high-fidelity quantum teleportation
#36Earlier quoted context omitted.
Physical qubits are much more sensitive to transmission noise than physical bits. If you want to transmit qubits, teleportation allows you to do it with higher fidelity than by physical transmission. Why do you want to transmit qubits? For various emerging quantum information technologies, each with different potential economic impact.
Does this mean quantum gizmos will ‘teleport’ the data over space instead of using wires? Like, will a quantum processor pull the data in the quantum ram using teleportation?
So perhaps distributed quantum computers spread across a university, city or country.
Also, remember, you still need wired or wireless transmission of bits to do the teleportation protocol.
Re: Sustained, high-fidelity quantum teleportation
#37context: Using term teleportation makes sense in the quantum realm. No-cloning theorem in quantum physics says that it's impossible to do exact copy of unknown quantum state. But it turns out that you can teleport it when the original state is destroyed. You can't have exact `cp` command for the quantum state, only `mv`. If this makes you think linear logic, you are right.
So that could neatly solve the philosophical teleportation problem? Ie if you teleport and the original isn’t destroyed. Which one are you?
Re: Sustained, high-fidelity quantum teleportation
#38Earlier quoted context omitted.
You entangle two systems but in order to actually complete the teleportation you need to measure one system and then convey the outcome of that measurement to the other party. This information is needed by the second party in order for them to be able to correctly collapse the state of their system into one that is identical to the original system being teleported. The information that the first party must convey to…
This makes zero sense. If the information must be conveyed classically anyway, what's the point?
So, before QM there was already a sense in which you could teleport an object: simply measure its state perfectly and send that information to another location and have them reconstruct that state particle by particle. In principle the new system would be indistinguishable from the original system and you could claim that you've teleported it. Now, with the discovery of quantum mechanics, this process no longer works because there is no way to measure the complete state of a quantum system. For example, you could measure the position of each particle to arbitrary accuracy or you can measure the speed of every particle to arbitrary position, but you can't do both (Heisenberg's uncertainty principle). So, it would seem like one could not construct a perfect replica of a quantum system in a new location by measuring its state in the original position.
The cleverness of quantum teleportation is that you use entanglement to sort of short circuit this limitation. You let entanglement do the heavy lifting to sort of "copy" the state from one location to another and then perform a measurement in the original location to uncover just enough information so that the person in the second location can manipulate its system to reconstruct the original state.
It's sort of like reconstructing the state without actually knowing what that state is.
Now, an interesting side effect of the quantum version is that the first measurement of the original system is necessarily destructive. As such, it's not like you'll end up with two copies of the same thing (which is what would happen in the classical version) so there's no discussion necessary around the distinction between teleportation and cloning. Classically you'd be cloning the system but quantum mechanically you'd really truly be teleporting it (in fact, there's a result in quantum mechanics called "the no cloning theorem" that proves that cloning in QM is impossible).
Re: Sustained, high-fidelity quantum teleportation
#39Earlier quoted context omitted.
So that could neatly solve the philosophical teleportation problem? Ie if you teleport and the original isn’t destroyed. Which one are you?
But if they destroy you and recreate you, are you still alive or die in the process?