Record-Setting Quantum Entanglement Connects Two Atoms Across 20 Miles - Slashdo...
source link: https://science.slashdot.org/story/22/07/09/158243/record-setting-quantum-entanglement-connects-two-atoms-across-20-miles
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Record-Setting Quantum Entanglement Connects Two Atoms Across 20 Miles
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Researchers from two Germany universities 'have demonstrated quantum entanglement of two atoms separated by 33 km (20.5 miles) of fiber optics," reports New Atlas.
Besides being a new distance record, "The team says this is an important step on the way to realizing a practical quantum internet."
In their experiments, the team entangled two rubidium atoms kept in optical traps in two different buildings on the Ludwig-Maximilians-University Munich campus. They were separated by 700 m (2,297 ft) of fiber optics, which was extended out to 33 km with extra spools of cable. Each atom was excited with a laser pulse, which causes it to emit a photon that's quantum entangled with the atom. The photons are then sent down the fiber optic cables to meet at a receiving station in the middle. There, the photons undergo a joint measurement, which entangles them — and because they're each already entangled with their own atom, the two atoms become entangled with each other as well.
While photons have been entangled over great distances before, this study marks a new distance record for entangling two atoms, which could function as "quantum memory" nodes, over fiber optics.
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Mod parent up. This is the appropriate response to the GP.
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What's the advantage of sending entangled photons instead of ordinary photons?
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The article isn't very clear. My previous understanding is that we don't know how quantum entangled particles communicate/transmit information.
It sounds like these photons are just a method of creating the initial entanglement? -
You can't read an entangled photon without unentangling it. Which means that you can tell if any data packet has been intercepted and switch encryption keys, safe in the knowledge that you know precisely what information a third party has obtained - and what it doesn't have.
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my comment was about entanglement and the apparent fact that it works no matter how far apart things are, in actual 3d distance.
string theory wants to get into 11 dimensions.
spacetime is often considered 4 dimensions.
my complaint is when people keep saying that entanglement works 'across a vast distance' and I think we're just missing at least one dimension, if not more. in that way, its 'off' in the x,y,z but its close in some other axis. and things only affect each other when they're close.
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IIRC, the math for Relativity has 16 dimensions. It's just that most of them are zeroed out. This means that effectively it has 4 dimensions. But I don't remember the basis of why they were zeroed out. It could be a combination of "to make the math simpler" and "we don't need them to explain the results we've gotten".
OTOH, just because things are close in one dimension doesn't mean that there exists a direct path through that dimension. E.g. two things happening "at the same time" (i.e. outside of each
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It's not silly. There is more and more strong evidence to suggest that time isn't even an actual thing. Time may very well just be how we perceive cause and effect actions in the quantum realm. It's possibly all an illusion like color. The color purple is a made-up thing. There is no "purple" wavelength of light. The same is quite possibly true for time and gravity.
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Of course time is an illusion; lunchtime doubly so.
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we can only see 3 dims (time is not a dimension, sorry, its just not).
and since this entanglement stuff seems to 'work' across big 3dimensional distances, it has to be concluded that they are close by each other, but in ways we just cant see YET.
the universe works by 'nearness'. how else can entanglement be explained? I still believe in the close-effect concept and nothing happens at a distance. so if we SEE a distance but see an affect, we must conclude that we are not seeing all there is to see.
Entangleme
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The technical term is "spooky".:-)
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They always write these announcements as if I can just go order the parts to make this from Digikey and hook it to a USB3 adapter that emulates some Ethernet controller. And that just to hold us over until DLink/Delta/Netgear have $18 products online.
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Well, I think the kicker is that you need to keep them at super-cooled temperatures. That's the part that really difficult to mass-produce, since the smaller something is, the more sensitive it is to the difference in heat to the rest of the environment.
OTOH, there are those working with ions trapped in crystals, etc., that think they may be able to keep entanglement at room temperature. You may need a specially doped diamond with atoms of a particular isotope of Nitrogen spaced at a careful distance from
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article:
'the two photons could become entangled with each other and lose connection with their ions '
So entanglement changes can not be made between the two originating points using their emitted photons because the photons are no longer entangled with those atoms.-
To be clear, the second linked article from 2019 [newatlas.com] does not match the new article from 2022. [newatlas.com]
Suddenly in the new article the entanglement between the photons and their ions are maintained when the photons themselves are entangled - so which is right, 2019 or 2022?-
I would trust the peer-reviewed 2022 article over the mass-audience 2019 article. It's possible that the 2019 article just got it wrong. It's also possible that scientists have developed new tricks since 2019 to transfer the entanglement. I would lean slightly towards the first explanation, because if the photons really did lose entanglement with the original ions, the distance-doubling truck doesn't seem like it would be very helpful for building a long-distance link.
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But but but... the joint measurement (whatever that means) of those photons _did_ "re-entangle" the atoms. That's a word, right? And that's what they're saying happened, right?
Sigh... if only quantum physics had been offered in my local community college. Or in an Army correspondence course. All this would be MUCH clearer.
I had to look up "entanglement" of course, just to be absolutely sure I was understanding all this.
https://en.wikipedia.org/wiki/... [wikipedia.org]
VERY nice article. But I'm not sure how much it r
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"re-entangle" the atoms. That's a word, right?
If you want to be old-timey and UTF8 works, you could write "reëntangle."
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...how stuff disappears from my lab!
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Is anybody actually asking for that? Is there any need?
Seems to me like a solution looking for a problem.
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Read "Halting State".
Of course, that's fiction. -
"Quantum Internet" is typically shorthand for using quantum mechanics to perform unsnoopable cryptographic key agreement over a distance. The applications for that are rather more obvious: Alice and Bob can set up a shared key without worrying about advances in cryptanalysis breaking the key exchange or agreement protocol.
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How much will the hardware cost? Is it something I can have at home?
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How much does gigabit Ethernet cost? Can you get it at home? What about 10GE?
Right now, the answers to your questions are "you have to build it yourself in a lab" and "see above". When quantum networking is first commercialized, the answers will be "a lot" and "only if you are rich and well-connected". The likely end goal is to make it accessible enough that the answers will depend on whether your government wants you to have that kind of technology.
In those respects, it's not much different from any ot
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You can actually generate entangled photons fairly cheaply, at least compared to other quantum stuff, so it's a possibility. It doesn't seem terribly likely you would want to though.
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My understanding is that it's snoopable, but only at the expense of revealing that it is being wiretapped, at which point you'd switch keys. So only snoopable at the level of single packets, never more than that.
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To be specific [wikipedia.org], it allows parameters of the protocol to be chosen such that either that eavesdropping or key agreement is guaranteed to fail. It can be hard to distinguish eavesdropper-induced noise from other kinds of noise, so one might not be certain whether the protocol failed due to an eavesdropper or for some other reason.
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would practical quantum internet means practically 0 lag for any point to point connection? And also quantum crypto?
That does seem highly useful!
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Entanglement is read only as far as I can see.
Instant transport of data is a misconception that they do not correct because then their quantum internet doesn't sound like the promises that people wrongly imagine entanglement can do. You still have to send the entangled data which is limited to current speeds of optical transmission methods. Entangled data does not change, it is a fixed set of data such as encryption keys that is only useful for one use by the recipient. Encryption keys do not change unles
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Practically though is this a new discovery or does it have any potential use?
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It's not a new discovery and has no practical use that anyone's been able to conceive of. It does not appear that you could use it for information transfer. It's just weird and fun to play with.
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1. It would allow you to have 100% knowledge of which data packets were spied upon, because spying on the packet would break entanglement.
2. If the ER=EPR conjecture is correct (layman's version: the maths for entanglement is identical to the maths for wormholes, the two may in fact be different ways of seeing the same thing) AND you can stabilise them with negative energy, THEN you can use entanglement to transmit data that is completely impossible to spy on.
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Long distance entanglement could possibly have scientific applications for some long baseline measurements. There have been (serious) proposals to use atomic interferomeeters as gravitational wave detectors, and some proposals that allow improved visible light interferometry using entangled systems. Both are pretty far out, but not crazy
qauantum encrypted communication can in principal make it impossible to monitor without being detected - but that is rarely the weak link in encryption systems now.
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