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Sustained, high-fidelity quantum teleportation

news.fnal.gov

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Re: Sustained, high-fidelity quantum teleportation

#91

Post by [deleted] »

pontus wrote: post #75
edge17 wrote: post #51

Earlier quoted context omitted.

Maybe I'm dense, but I still don't understand. The cloning explanation made sense to me, but to the original question - how does the recipient know the message is done being sent without the sender picking up the phone and calling the recipient...? i.e. Is there some equivalent of a termination code/header sort of thing that the recipient is looking for in the 'bit stream' or whatever? Or am I not even thinking about…

The receiver does not know that a message has been sent until the first person contacts them classically. It's a common mistake to think that quantum teleportation is a new way of sending information. It's really a way to use classical communication in order to leverage entanglement to bypass various limitations of quantum mechanics. So, the two people communicating would e.g. start out together and create a pair of…

[deleted]

Re: Sustained, high-fidelity quantum teleportation

#92

Post by [deleted] »

pontus wrote: post #75
edge17 wrote: post #51

Earlier quoted context omitted.

Maybe I'm dense, but I still don't understand. The cloning explanation made sense to me, but to the original question - how does the recipient know the message is done being sent without the sender picking up the phone and calling the recipient...? i.e. Is there some equivalent of a termination code/header sort of thing that the recipient is looking for in the 'bit stream' or whatever? Or am I not even thinking about…

The receiver does not know that a message has been sent until the first person contacts them classically. It's a common mistake to think that quantum teleportation is a new way of sending information. It's really a way to use classical communication in order to leverage entanglement to bypass various limitations of quantum mechanics. So, the two people communicating would e.g. start out together and create a pair of…

[deleted]

Re: Sustained, high-fidelity quantum teleportation

#94

Post by WFHRenaissance »

metadaemon wrote: post #86
pontus wrote: post #75

Earlier quoted context omitted.

The receiver does not know that a message has been sent until the first person contacts them classically. It's a common mistake to think that quantum teleportation is a new way of sending information. It's really a way to use classical communication in order to leverage entanglement to bypass various limitations of quantum mechanics. So, the two people communicating would e.g. start out together and create a pair of…

I know this is probably a stupid question, but would a text message be considered classical in terms of communication?

Yes

Re: Sustained, high-fidelity quantum teleportation

#95

Post by terminalcommand »

edge17 wrote: post #84
pontus wrote: post #75

Earlier quoted context omitted.

The receiver does not know that a message has been sent until the first person contacts them classically. It's a common mistake to think that quantum teleportation is a new way of sending information. It's really a way to use classical communication in order to leverage entanglement to bypass various limitations of quantum mechanics. So, the two people communicating would e.g. start out together and create a pair of…

Got it, thanks for the explanation. Also, not to get ahead of ourselves (understanding this is research), but what is the use/benefit of this method? We can already send and receive information over great distances with and without wires at seemingly high speeds. Is this a new level of speed? Are there some previous limitations of distances that are now surmountable? Is the power or cost envelope required somehow red…

Maybe it may be useful for achieving truly one-way communication? Could it also be a stepping stone for transmitting state-heavy data? For example a human being with a consciousness :).

Re: Sustained, high-fidelity quantum teleportation

#96

Post by ksec »

pontus wrote: post #75
edge17 wrote: post #51

Earlier quoted context omitted.

Maybe I'm dense, but I still don't understand. The cloning explanation made sense to me, but to the original question - how does the recipient know the message is done being sent without the sender picking up the phone and calling the recipient...? i.e. Is there some equivalent of a termination code/header sort of thing that the recipient is looking for in the 'bit stream' or whatever? Or am I not even thinking about…

The receiver does not know that a message has been sent until the first person contacts them classically. It's a common mistake to think that quantum teleportation is a new way of sending information. It's really a way to use classical communication in order to leverage entanglement to bypass various limitations of quantum mechanics. So, the two people communicating would e.g. start out together and create a pair of…

Thank You.

That destroy my hopes of having (Close to ) Zero Latency Communication with Quantum Teleportation / Entanglement. We are still bound by the speed of light!

Re: Sustained, high-fidelity quantum teleportation

#97

Post by Rooster61 »

So, something that always bothered me, and my admittedly ignorant understanding of QM as a non-physicist. I understand that the quantum state of a particle can be teleported, and that classical information must be passed to observe the particle and collapse the state correctly.

My question is, if we can't observe the particle, how do we know that that particle is entangled with the original one?

Re: Sustained, high-fidelity quantum teleportation

#98

Post by fastball »

sabellito wrote: post #2

I'm confused, as I'm an enthusiast but definitely no physicist. The article states that quantum information is being teleported via entanglement. However, it was my understanding that one cannot transfer information in such a way as the "information" is only revealed when interacting with the particle. Could someone perhaps clarify what's going on?

We had digital data storage before we had the internet. Back then, if you wanted to share digital information with someone else, you had to save that information to a hard disk (or similar) and physically transport it to their location.

Then we invented the internet and now you can transmit digital information between digital computers over wires / EM signals.

Quantum teleportation / entanglement does the same but for quantum state rather than just digital state, which allows quantum computers to communicate with each other. Without this technology, quantum computers would not be able to communicate with each other over a network. So you still need to use wires / EM waves in order to transmit the data, but the data you are transmitting is quantum.

Technically you're not actually sending qubits over the wire though, you're sending 2 classical bits per quibit which are able to tell the other system what each qubit in the target system is supposed to look like, but effectively you can pretend you're sending qubits over the wire.

Re: Sustained, high-fidelity quantum teleportation

#99

Post by Poc »

bluesign wrote: post #54
cambalache wrote: post #14

Earlier quoted context omitted.

No communication is possible BUT, I have this toy scenario where a "quasi-communication" may be possible in FTL speed. "2 generals command 2 armies hundreds of km apart. They want to attack a common enemy, there are 2 options, A) And all-front attack. B) From the flanks. The generals want the plans to remain uncertain until the last second before the attack. So from an intermediate point, they send two "entangled coi…

Sorry but this example doesn't make sense, how it is faster than light?

It is not faster than light. I think what he wanted to show was a situation, in which entanglement and quantum mechanics, are superior to classical physics. i.e someone using quantum mechanics would have an advantage over someone who don't.

However, as he said, in this situation the two generals could have agreed on something else, like if it was raining or not.

In fact, something they could have done is to flip a coin, and split with a copy of the result, which they only look at when they launch the attack. It would have the same effect.

With a random variable (the coin flip), that is hidden until revealed, we achieve the same results as quantum mechanics.

Scientist call them "hidden values" and Einstein hopped we could explain the "spooky action at a distance" with such hidden variables. But we can't, Bell proposed an experiment with entangle state which measurement could not be explained by such hidden variables, and Aspect did the experiment and obtained the predicted results.

So there exist situation where we can use entanglement to achieve better results, for example in "non-local games", where players sharing entangled state can win with probability 1, when "classical player" with probability < 1

Re: Sustained, high-fidelity quantum teleportation

#100

Post by freeflight »

mrtesthah wrote: post #43
pontus wrote: post #38

Earlier quoted context omitted.

Great question! This gets to the heart of why quantum teleportation has any value at all. 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…

It sounds like start trek’s transporter beams may be more accurately described than we thought.

It's also where the meme comes from how Star Trek transporers are actually suicide booths [0].

[0] https://arstechnica.com/gaming/2017/09/is-beaming-down-in-st...

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