Quantum entanglement, the spooky action at a distance that promises to be so useful for things like high-powered computing and security, is generally considered a function of the tiny world. It's easy — OK, not easy, but relatively practical nowadays — to take two particles or two microscopic things and intertwine their fates. Now for the first time, scientists have accomplished quantum entanglement on the macro scale, entangling two millimeter-sized diamonds.
The findings, published in this week's issue of Science, are a potential major leap for both quantum and classical mechanics. It's the first time entanglement has been achieved between two fairly large objects — and at room temperature to boot.
As regular readers know, entanglement is the process of connecting two separate things, be they photons or nanoscale objects, so that they behave the same no matter their distance apart. What happens to one particle also happens to the other, even if they are separated by the entire universe.
Researchers at Oxford University took two small diamonds, about 3 millimeters square and 1 millimeter thick. They exposed them to incredibly short bursts — about 100 femtoseconds — of laser light, in a method called ultra fast pump probe spectroscopy. What happened next is complicated: The light induced some vibration in the lineup of the molecules in the diamond crystals. These inherent oscillations (present in all atoms, they're just being taken advantage of here) are known as phonon modes. The pulse excited one phonon mode in both of the diamonds, and also produced two photons, which were scattered by the diamonds and which would be used to entangle the phonon states. Then the scattered photons were brought together, using a complicated setup involving a beam splitter and single-photon detectors.
The two diamonds were about half a foot apart, but when one of the photons was detected, the two diamonds were sharing a phonon. In other words, what happened to one diamond happened to the other. The researchers confirmed this by working backward, de-exciting the phonon and emitting another photon, which was itself detected. Entanglement lasted about 7 picoseconds, so it's too short to be used in a quantum computer or other device — at least for now.
"The two diamond samples coherently shared one phonon, which is the hallmark of a quantum-entangled state," explains L.-M. Duan, a physicist at the University of Michigan who wrote a perspective paper accompanying the Science paper. "These results provide a striking example that entanglement is not particular to microscopic particles but can manifest itself in the macroscopic world, where it could be used in future studies that make fundamental tests of quantum mechanics."
"[...]what happened to one diamond happened to the other" Not really, this statement is very misleading. It's actually like two clocks which tick in the same moment (the ticking is "entangled"). Does ticking happen the same time no matter where they are? Yep. If something happens to one clock (like breaking it), will it happen to the other? Nope, they will just not tick along anymore. The same with diamonds, if ANYTHING happens to one diamond, the other is not "entangled" anymore. Wow - I've just entangled objects which are 15cm sized!!!
i think its a little bit more complicated than 2 clocks...
lets brainiacs do their job and be happy when they get excited ^^
bored? lets go mine the stars... ^^
The clock scenario is very simplified and inaccurate in how it describes what happened in that lab. A more accurate description would be a tennis ball machine. Imagine two machines pointed at you firing balls. Normally, you'd picture one ball coming from each machine. What happened with these diamonds would be the exact same ball originating from both machines... so for a very short moment, those machines were one in the same--so to speak.
I'd imagine this could be used for communication with a very advanced "switch" technology so that no two entangled points interact directly with each other.
Imagine two vessels separated by 1 LY with Earth in the middle. Ship A sends a message through its quantum "radio" which is measured in a switch (location X) on Earth. That switch contains one of the entangled pair from Ship A and(1) decodes the message and (2) figures out where that message is supposed to go, then encodes the same message on a different entangled pair, the partner of which is on Ship B. This is basically a 'cell tower' for quantum particles (we don't need diamonds for this, can be done with a single atom). And it would allow "callers" to communicate with anyone on that network (switch). Instead of direct and limited ship to ship contact.
That can be applied to this experiment because both diamonds emitted a single particle. Well, if Ship A has one diamond and the Switch (X) has another diamond we could measure pulses of phonons as the 0s and 1s that comprise our digital world. So in other words, Ship A would have to induce its diamond to pulse phonons (i.e. 01 001 010 101 etc.) and simultaneously the diamond embedded in the switch will pulse phonons as well. This is how we communicate FTL. And it doesn't break physics by violating causality because realistically speaking we're not talking about literally sending a message upstream of time (back to the 1950s) we're simply cutting down signal latency to 0.
great explanation dude ^^ latency 0... so beautiful ^^
so that means that MARS-EARTH comunication will be instantlly transmited with this tech ^^
if so ... cool... ^^
bored? lets go mine the stars... ^^
Cool. So when are we going to hear about a three-way connection?
Also, the reason we aren't breaking lightspeed is because the effect isn't travelling at all, it's just in two places simultaneously. Please explain to me: does gravity, thought it's effect is reduced by distance, still communicate it's effect instantaneously as a distortion of spacetime? i can't fin a clear answer.
Thanks vt, I've been seeing you on these boards for a while--nice to meet you!
3-Way communication may not necessarily be possible. For example, Ship A carries half (a1) of entangled pair a1a2, the other half (a2) is in the switch. Ship B carries b1, the other half (b2) is in the switch. Ship C carries c1, the other half (c2) is in the switch. You're asking how do we connect Ships A, B, and C on a "teleconference" for instant 3-way communication?
I suppose that a2, b2, and c2, could be encoding to a conference connected (CC1). But CC1 would need to simultaneously communicate with a1, b1, and c1. This could create a feedback loop, basically making the value null (dropped connection because the system can't be that many different states at one time). This would necessitate a third receiver on each ship (a3, b3, c3). This might be sufficient to solve for 4, 5, 6... n-way communication, but it also might be true that each additional connection will geometrically expand the required number of entangled pairs. This could prove problematic for larger conferences. But considering that we can do this with individual atoms, even if a ship carried 1,000,000 possible connections, if we could store/read/write those atoms in a single chip.
So far as we know, the effect of gravity is instantaneous to infinity. Very interesting that you bring that up, because that would mean that the force of gravity moves faster than c.
Hummm? . . . Remember the FTL claim at CERN? I'm wondering if Quantum entanglement had an effect on that experiment?
Actually lawsonrw, gravity waves propagate at exactly the speed of light. This is further evidence for gravity having a carrier particle ( IE: Graviton ) that we just have yet to find. This is a part of General and Special Relativity.
What this means is that if the sun simply vanished, it would be 8 minutes before we knew about it.
Very cool stuff, I've always thought that entanglement could be the solution to providing Internet on distant space stations and other planets or moons when we decide to set up shop there. Better than requesting an Earth based web page on Mars and waiting 12+ minutes to get a response. That's presuming the signals going at the speed of light and Mars isn't on the opposite side of the sun at the time.
Could this type of technology be used for wireless electricity?!
@ zecchio, though some literature will say that the speed of gravity is c, if you dig a little deeper you will find that attraction is always towards the instantaneous position of the object, not where it was at the time a gravitational wave would have been released. In other words, if the speed of gravity were c, Earth would be attracted to where the Sun was 8 minutes ago. Mathematically speaking, that would cause the orbit of Earth to spiral outward. But since that clearly isn't happening and Earth's orbit is observed to be stable, Earth is attracted to the instantaneous position of the Sun. Which means the effect of the Sun's gravity reached Earth before the light released at the same time.
nice to meet you too ^^ cool stuff that youre saing here about gravity ! didnt knew that eather ^^
bored? lets go mine the stars... ^^
one step closer to quantum teleportation..... This will be really interesting when we get to the point we can do this with cats, lol. Maybe then we can finally get some answers, or not.
I don't know about anyone else, but these phonon modes sound an awful lot like radio channels. Multi-way communication might be possible, scientists are just fixated on entanglement being between two objects only. They need to expand the number of objects they are trying to entangle.
Diamonds are being used instead of single atoms, because diamonds don't require as much energy to entangle. You don't have to supercool and hold diamonds in a magnetic field to perform the experiment.
Actually, the jury is still out on the "speed of gravity".
On the one hand, General Relativity prohibits any object from traveling faster than the speed of light. However, changes in a coherent field, (such as a gravitational field), appear to effect the whole field instantainiously
To put it simply,observations of black holes' effects on distant objects where the distances should make relativistic effects observable have so far not yielded the expected results.
I find it interesting that such a question should be asked in the context of this article. If we confirm that changes to gravitational fields produce instantainious effects over relativistic distances, (spooky action at a distance), the implication would be that gravitational fields entangle massive objects on the astronomical scale.
@ Falconer, you are wright with regards to 2 way comm... each ship would need a sending unit and a receiving unit (much the way cell phones use one signal to send and anoher to receive voice). You're also dead on regarding the need to supercool and lock in magnetic fields for molecules as opposed to diamonds. The good thing is that that type of entanglement lasts a little longer. The bad news is, we might actually prefer to entangle macro objects (like diamonds) because once we figure out how to make entanglement last longer they'd be more stable. (Imagine losing Communications and your 1 LY away!). Like I said, the problem with that is "once we figure out."
@ blinders, very interesting relating gravity to entanglement. Though its not the same thing, there could be an underylying 'common ground' that allows both gravity and entangled objects to "communicate" across large distances.
this is awesome! i need more of these guyz!.....
@lawsonrw, the tennis ball machine scenario is the illis dude!..love it!...I hope ya analogy is right anyways!
7 picoseconds is longer than 6.. but not long enough for consumer computers right? *shrug* let me know when it reaches 1/4 of a second or more ;)
>I can't help but think that the effect that gravity has on space/TIME (ie>the passage of it) has some type of correcting affect on gravity's speed relative to the speed of light :)
I believe the Mythbusters have something to do now. . .if the sun disappeared, would we feel it before/while seeing it?