This might sound like a very naive question but I am curious as to how the data was actually transmitted.
Researchers quantum teleport particle of light six kilometres
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Re: Researchers quantum teleport particle of light six kilometres
#42I posted this in a duplicate thread: For those thinking that this is a step towards faster-than-light (FTL) communication: As far as I know it's fairly certain that quantum entanglement will not allow for FTL communication. Basic principle is that while measurements between both sides will be correlated, it's not possible to tell how they are correlated until both sides compare measurements. https://en.wikipedia.org/…
Is "measurement" or "observation" a simplified term for a complex process? It can't be as simple as a human "looking" at something since there's nothing special about humans (that I know of). I really wish I had the time and capability to understood how quantum entanglement really works. It seems a lot like magic if you take the layman explanations at face value.
Re: Researchers quantum teleport particle of light six kilometres
#43I had thought that quantum entanglement could not be used for communication because the state that is transmitted is random, and cannot be controlled at either end. But, there are quotes in this article to the contrary. e.g.: “Such a network will enable secure communication without having to worry about eavesdropping, and allow distant quantum computers to connect,” says Tittel. Was my understanding mistaken?
It isn't directly usable for communication, but you can use the shared random state as a one-time pad for provably-secure communication over nonsecure conventional channels.
Re: Researchers quantum teleport particle of light six kilometres
#44I posted this in a duplicate thread: For those thinking that this is a step towards faster-than-light (FTL) communication: As far as I know it's fairly certain that quantum entanglement will not allow for FTL communication. Basic principle is that while measurements between both sides will be correlated, it's not possible to tell how they are correlated until both sides compare measurements. https://en.wikipedia.org/…
Not only do they have to communicate the shared measurement (classically) but they also need to have a shared EPR pair to begin with.
Re: Researchers quantum teleport particle of light six kilometres
#45Re: Researchers quantum teleport particle of light six kilometres
#46Just to give a concept of how difficult this is: > “The challenge was to keep the photons’ arrival time synchronized to within 10 pico-seconds,” > “Since these detectors only work at temperatures less than one degree above absolute zero the equipment also included a compact cryostat,” said Tittel. The dark fiber seems like it was important for synchronizing the clocks. And while they claim this could be used for encr…
> If this technology was refined, you'd just use this system to send secure messages without the need for an encryption key. As far as I know, I don't think that meshes with what actually happens. This has nothing to do with the message being secure; anyone with all the pieces could read the message. The important part is, since observation effects quantum state, the receiver can determine whether a third party obser…
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Re: Researchers quantum teleport particle of light six kilometres
#47I had thought that quantum entanglement could not be used for communication because the state that is transmitted is random, and cannot be controlled at either end. But, there are quotes in this article to the contrary. e.g.: “Such a network will enable secure communication without having to worry about eavesdropping, and allow distant quantum computers to connect,” says Tittel. Was my understanding mistaken?
I took a quantum optics course once. It's true what you say that entanglement can't be used to communicate (by itself), hence no problems with relativity, speed of light etc. This is known as the No-communication theorem:
https://en.wikipedia.org/wiki/No-communication_theorem
But together with a conventional communications channel (e.g. radio signals), you can use quantum entanglement to create a secure communications channel. This combination is called quantum teleportation (as opposed to just quantum entanglement):
Re: Researchers quantum teleport particle of light six kilometres
#48Correct me if this sounds noobish. So they have teleported state that has Information that can be decoded to bits and bytes(?) Forget about human teleportation for a sec, isn't this a big deal in a not so far future for telecommunication?
They did nothing of the sort. Quantum physicists use words like teleport to say completely different things then what those words actually mean.
This is correct. I'll quote the article here: "What happened is the instantaneous and disembodied transfer of the photon’s quantum state onto the remaining photon of the entangled pair, which is the one that remained six kilometres away at the university,” says Tittel". So teleport in this case doesn't really mean teleport, it just refers to the "teleportation" or transfer of a quantum state.
Re: Researchers quantum teleport particle of light six kilometres
#49Teleportation is not possible. Quantum teleportation is the transmission of the exact state of a photon from one place to another. Still, even this happens at less than the speed of light. Otherwise it would violate causality. The media plays fast and loose with terminology either out of plain ignorance or the desire to sell a story.
> Teleportation is not possible. Quantum teleportation is the transmission of the exact state of a photon from one place to another. Still, even this happens at less than the speed of light. Otherwise it would violate causality. Maybe I'm remembering my QED special topics class incorrectly, but I thought the state teleportation is believed to be instant. The problem is to extract the state information, the transforma…
So many advancements in physics have been the result of a smart person abandoning some "law".