Entanglement

Purple Brain

Experienced member
1,613 179
Researchers Teleport 10,000 Bits of Information in 1 Second

Probably only interesting for us nerds but, I found the following in para 5 to be questionable: “Specifically, the qubits in the sender circuit became entangled with those in the receiving circuit because they exchanged photons.”. I have emphasised that which causes me concern.

While I wouldn’t baulk at any teleport device that would work only as quickly at the speed of light [exchange of photons] I thought the mechanics of the entanglement phenomenon – if any such phenomenon exists of course – remains unknown and therefore undefined. Plus there has always been an explicit expectation that communication via entanglement would be instantaneous and not limited to the speed of light.

I’m all for making advanced scientific research more popular, but muddying the waters around key concepts and hijacking terminology and pressing it into an alternate usage just because they have gained currency outside the narrow confines of research institutions probably does more harm than good to the advancement of understanding in the wider community.

OK mashable isn’t THE place to go for cutting edge and accurate reporting and who cares anyway, but say somebody intelligent and motivated sets off to develop an ‘entanglement device’ based upon exchange of photons. They achieve it. Great. But it’s not a quantum leap in technology (pun intended). However, had they been motivated to design and build a genuine entanglement device – and achieved it – THAT would be something.

I guess that’s what I’m saying. Keeping things clear and honest may not be headline grabbing and popular, but will do greater good in the long run.
 

Shakone

Senior member
2,458 665
Do you know if they mean that there was initial exchange of photons, to create the entanglement and then entanglement allowed info to travel faster than light, or do they mean that info was just travelling at the speed of light? I'd hope the former.
 

Purple Brain

Experienced member
1,613 179
It's unclear, but even if it was 'just' an initial exchange of photons that limits the whole enterprise to the speed of light. If it all works instantaneously after that initial exchange you still have to wait for the initial exchange to take place. No biggie on a communications distance of 6mm, but 6 light years and it's time to go and get a coffee.

My guess is that the whole thing was photon driven. Nice work, but not entanglement.
 

Shakone

Senior member
2,458 665
It's unclear, but even if it was 'just' an initial exchange of photons that limits the whole enterprise to the speed of light. If it all works instantaneously after that initial exchange you still have to wait for the initial exchange to take place. No biggie on a communications distance of 6mm, but 6 light years and it's time to go and get a coffee.

My guess is that the whole thing was photon driven. Nice work, but not entanglement.

Not as I understood it, because entanglement is always based on an initial connection of particles. For example particles that come in pairs and have opposite spin (there's a name for this but it escapes me) are initially connected, then they are separated by whatever distance you want. Then when you adjust something in one, the other partner adjusts at faster than the speed of light, because there is still some 'entanglement' between the two that we don't understand that stretches across that distance. So what I mean is, if the photon transfer is just the way to get them initially connected, then it's still based on entanglement. But the article wasn't clear.
 

Purple Brain

Experienced member
1,613 179
Not as I understood it, because entanglement is always based on an initial connection of particles.
Yes, that was the part that I hadn't previously given a second thought to. Not pointlessly rehashing an old topic, but that point was made clear in an article I read last week with respect to quantum cryptography and I remembered this thread.

Superficially this would suggest FTL communication is still effectively limited by the speed of light. OK, you can communicate with someone a million light years away instantaneously, but only after you've waited one million years for a particle to get there before you can do that.

What I am still confused about is that at The Very Beginning, all particles were entangled i.e. every particle in the universe is already entangled with every other one.
 

Shakone

Senior member
2,458 665
Yes, that was the part that I hadn't previously given a second thought to. Not pointlessly rehashing an old topic, but that point was made clear in an article I read last week with respect to quantum cryptography and I remembered this thread.

Superficially this would suggest FTL communication is still effectively limited by the speed of light. OK, you can communicate with someone a million light years away instantaneously, but only after you've waited one million years for a particle to get there before you can do that.

What I am still confused about is that at The Very Beginning, all particles were entangled i.e. every particle in the universe is already entangled with every other one.

How do we know that (bold) is true in the sense of entanglement in the experiment?
 

Purple Brain

Experienced member
1,613 179
How do we know that (bold) is true in the sense of entanglement in the experiment?
We don't. I wasn't really thinking of the experiment.

I was thinking that if there was a primordial singularity (big IF) then all particles are surely, by definition, initially connected.
 

Shakone

Senior member
2,458 665
We don't. I wasn't really thinking of the experiment.

I was thinking that if there was a primordial singularity (big IF) then all particles are surely, by definition, initially connected.

Ok, thought there may have been some related research.

I wasn't sure connected implies an entanglement property, but it could well be that in the beginning, it was all entangled.

I don't have enough physics understanding, so I rely on old philosophies, such as 'everything must have an opposite', and entanglement is then a way of utilising that to transmit info faster than the speed of light.
 

Purple Brain

Experienced member
1,613 179
Ok, thought there may have been some related research.
The article I read last week attached. The Economist - September 21 2013.
 

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