TLDR: Researchers were able to send and receive entangled photons over a fiber optic cable that was simultaneously carrying a classical (non-quantum) signal typical of high speed telecommunications. They managed to accomplish this without the classical signal significantly interfering with the quantum measurements.
This was all done in a laboratory using a combination of standard telecommunications equipment for the classical signal and specialized equipment for the quantum signal. It was NOT done on a fiber carrying real internet traffic as the article would suggest.
Correct, but still amazing because it means quantum internet is achievable over existing infrastructure. Not needing to lay down all new lines around the world for quantum transmissions will mean it gets adopted much faster. Even if specialized equipment is needed on either end of the cable, the hope/assumption would be that specialized equipment on either end will become cheaper as tech advances and scales upward - still a long ways off but cut down significantly.
Yeah it’s absolutely an awesome accomplishment, it just bugs me whenever articles spread straight up false information.
What’s the upshot of this, even if the article’s hyperbole is accurate? I’m assuming it’s not as spooky or sci-fi as the terminology sounds to a monkey like me.
It shows that it’s possible to send entangled photons over existing fiber infrastructure without building something totally new, which as I understand it has applications in cryptography, secure communications, and quantum computing.
IIUC, quantum entanglement at a distance provides for faster than light/instant communication of state changes. High frequency trading, and dark orderbooks, is the only known economic application (space communications a far off application). I’m not sure why article avoided talking about this purpose.
You don’t understand correctly. Entangled particles do not allow for faster than light communication.
While the entangled photons may be thought of as changing state simultaneously, in practice, it’s not possible to use this to convey information, as doing so would break causality, and effect would be able to happen before its cause. Remember that what is commonly termed ‘the speed of light’ is actually better expressed as ‘the speed of causality’. The most useful application of what this experiment performed would be in the area of quantum cryptography.
So honest question here:
Why can’t it be used to transmit information? Wouldn’t we be able to capture the state and use that be turned into instructions the same way we use binary currently?
Binary is essentially just a series of “on” and “off” states that we capture and translate into instructions, so why can’t we do that with entangled particles? Like position 6 translates into instructions F and position 2 triggers instructions B.
I know this is overly simplified but I do not follow that we can’t send information this way when looking at it through this lense.
Watch these videos that explain the answer. Basically, the problem is that you can only use this to convey random information , which would be indistinguishable from not sending anything at all.
So you’re telling me my Bitcoin is quantum now?
/S
that’s not how that works, quantum entanglement can not be used to transmit information and thus doesn’t violate causality
I thought the whole point of entangled communication is that you didn’t need to “send” anything. It automatically flips the entangled bit on the other end, all that “spooky action at a distance” bidness. Why do the need to “send” entangled photons?
You need to prep by sending the entangled particles (photons in this case). The spooky action is when you act on 1, you also act on the other. The useful bit is the uniqueness of the link. It cannot be intercepted without it being obvious and detectable.
Think of it like voodoo dolls. It works at a distance, but you need to make the voodoo doll using a bit of the target, then send/take it elsewhere to stab.
I’m pretty ignorant of physics, but isn’t it only certain kinds of ways of acting on the first particle that “affect” the other, namely actions that measure a property of one particle that is correlated with the same property’s value on the other? At first you don’t know the value of either but you know they’re correlated; but then when you measure and collapse the wave function on one and discovered a value for the property, you have automatically collapsed the wave function on the other too, yielding a predictably correlated value. If it were just any kind of action that affects the other particle, you’d be able to use it to sent information instantaneously, which you can’t do. So it’s not quite like how people imagine voodoo dolls: do something to the doll (make a change to it) and the person feels the effect. But perhaps someone who studies this stuff can help clarify.
That’s fairly close. The only proviso is there are some ways to affect the results. You can’t send actual information along the link, but you can prove they were in communication. That proof requires information from the sending end however. It’s only provable once that information is sent. Basically they communicate faster than light, but can’t send information faster than light. Entanglement is weird.
Thank you. That is helpful and clear.
The “spooky action” is really just the determination of a particle’s spin on one side meaning you already know the other particle will have an opposite spin. This probably violates locality because you gain knowledge about something that’s non-local from a quantum perspective, even though entangled particles have to start local (there are opposing interpretations, like the de Broglie-Bohm). While in fiction this might suggest that changing the state of one particle simultaneously changes the other, in real life this just means extra information you mathematically shouldn’t have, and doesn’t really lead to FTL information transmission. What it does mean is that if you want secure communications you can use entangled particles to generate a secret key, determining the spin of them on either side, and you can be sure that they haven’t been tampered with and that the other side of the communication will be equal and opposite. It’s essentially a one-time pad.
Someone smarter than me, please go ahead and explain how this is going to be used to make life worse for all of us, probably in a deeply disturbing political reality that screams “the world Quinn from Sliders slid into and had to jump early because fuck this timeline”
Monkeys learned to send signals faster. Now monkeys can bomb other monkeys they don’t like faster.
It could actually be a good thing, since it opens up the possibility of unsnoopable channels of communication, using encryption that would be disrupted by any attempt to intercept it.
Also the ability to crack any of our current encryption almost instantly…
Quantum entanglement is different than quantum computing.
Not exactly; entanglement is a critical element of quantum computing for the encryption and decryption referenced.
Not what I understand. The encryption referenced is about having an immutably certain shared data source from entanglement that can be used as encryption/decryption input. Quantum computing does promise to crack current encryption technology in the future.
This is not 2015
You sound quite miserable, maybe you should stop thinking like this
Bet
Edit: it seems I will be loosing that bet.
