High-dimensional orbital angular momentum entanglement over a 1km fiber

https://www.osapublishing.org/optica/abstract.cfm?uri=optica-7-3-232

by bookofjoe • 6 years ago

36 20 6 years ago

osapublishing.org

tyingq2• 6 years ago

"future OAM-based high-dimensional long-distance quantum communication"

As a layperson, this is confusing. I thought you couldn't use entanglement for communication.

peteradio2• 6 years ago

It cannot communicate at faster than light speed. That is probably the limitation you are thinking of.

tyingq2• 6 years ago

Ok. But they are doing it over a 1km fiber optic cable. Which is relatively close to the speed of light if you use it as intended. So I remain confused :)

jerf4• 6 years ago

As others say, it doesn't enable FTL communication.

But if you have an entangled set X and Y, you can send your partner X while you keep Y. When you both look at X and Y, you will randomly get 0 or 1 while they get the opposite. While you can't control which you get, you can take advantage of the fact that only you and your partner know what these values are and it is guaranteed that nobody else knows what they are. You don't know how your partner has used this info until you get the conventional communication.

It's more complicated than that in reality but that's the principle of why it's useful.

echelon3• 6 years ago

Can you "nudge" the system without collapsing the entanglement? And if so, could you do so in a way that predictably impacts the value of the entangled property?

I find it hard to grasp that there's no clever way to impart information over entanglement (without relying on classical messaging).

Is the state of entanglement fragile beyond our limits to record or alter? What about an ensemble of thousands of entangled particles - could we statistically sample some of them and force how they resolve?

What are the different properties that can be entangled? Angular momentum (spin, orbital) ...? Surely there's something we can clock and predict in the real world without requiring us to collapse the wave function to know what the state would be.

heavenlyblue• 6 years ago

I think we need to invent a new term which basically means "an ability to make a binary decision based on a set of pre-agreed rules".

zaroth• 6 years ago

So for example, a perfect way to distribute entropy, e.g. for the use in cryptographic. But no amount of shared entropy can ever result in shared information.

javbit• 6 years ago

Could this, however, be used to create random bit streams for use in one time pads? I'd imagine it could solve the problem of sharing the large keys beforehand since you could generate it on the fly.

an_d_rew• 6 years ago

Only on HN does one discuss quantum entanglement and self-identify as a “layperson”... at the same time :-)

sebastianconcpt• 6 years ago

I'm fascinated by the contrast of conceptual abstraction and concreteness in that title (and work of course)

sabujp• 6 years ago

i thought this was about space elevators until i read the abstract

High-dimensional orbital angular momentum entanglement over a 1km fiber

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