First Evidence For Entanglement of Three Macroscopic Objects

[Telos]

http://www.aip.org/pnu/2005/split/722-2.html

The entire article is short enough to be quoted here.

First evidence for entanglement of three macroscopic objects has been seen in a superconducting circuit built at the University of Maryland. By examining an electrical circuit operating at temperatures near absolute zero, the researchers have found new evidence that the laws of quantum mechanics apply not just to microscopic particles such as atoms and electrons, but also to large electronic devices called superconducting quantum bits (qubits).

While researchers have previously created superconducting qubits, and other groups have entangled two macroscopic objects (Update 558), this research is the first to observe the quantum interaction of three macroscopic components: a niobium inductor-capacitor (LC) circuit plus a pair of Josephson junctions, each a sandwich of two superconductors separated by an insulator. Remarkably, all three macroscopic devices seem to act, when cold enough, like huge atoms. The LC circuit coupled the Josephson junctions in such a way as to transfer quantized oscillations of current in one junction to the other junction. The LC circuit was more than a simple connector; its condition depended upon the two Josephson junctions in a way defined by the laws of quantum mechanics.

The researchers obtained evidence of the entanglement indirectly, through the use of microwave pulses that probed the Josephson junctions; future experiments will seek to directly control the junctions and obtain evidence more directly. Superconducting circuits such as this one provide a promising route towards a practical quantum computer, which would require the entanglement of many qubits.

Scaling up superconducting devices to many-qubit systems should be possible once single superconducting qubits are perfected, according to team member Frederick Strauch, (now at NIST, 301-975-5159, Frederick.Strauch@nist.gov). The challenge will be to fabricate sufficiently high-quality circuits so that the superconducting qubits achieve the very low noise levels necessary for quantum computing. (Xu et al., Physical Review Letters, 21 January 2005)

Although the evidence was obtained indirectly, it shows that macroscopic objects, particularly electronic devices, can be entangled under highly specialized (and very cold) conditions.

The implications are obvious for quantum computers, but what are the implications for Quantum Metaphysics?

[beavis]

It said 3 objects. It did not say 3 particles. That condition could be satisfied by entangling pairs of particles in each 2 of the 3 objects. That is nothing new.

[Telos]

Beavis, it may not have been new in theory, but it's new in practice. Why is it some here don't understand the difference?

I'll have to put some kind of quote in my signature or something.

[Psan]

but what are the implications for Quantum Metaphysics?

The implications are.........everything is non-local.
Well, sounds old

Nonetheless its a technical achievement.

[Telos]

.....everything is non-local.

Or potentially non-local, since such non-locality is practiced under certain conditions.

[knucklebrain1970]

Ok, what do you guys mean by entangled? Of what significance is this? I'm trying to understand it from a lay mans point of view. I was a med tech major, but never got into physics.

Kevin

[Psan]

Quantum entanglement

[knucklebrain1970]

Does this have anything to do with the photon experiment in England? Where two photons were launched in separate directions, then an electrical charge was applied to one, in which the change was visible in the other, which kind of broke the speed of light theory? Or perhaps that theory is irrelevant in that case.

See below, Am I on the right track here? Is this basically stating that two particles are always somewhat interrelated, no matter what external forces are applied to them?
Kevin

"Schrödinger coined the term 'entanglement' to describe this peculiar connection between quantum systems (Schrödinger, p. 555):

   When two systems, of which we know the states by their respective representatives, enter into temporary physical interaction due to known forces between them, and when after a time of mutual influence the systems separate again, then they can no longer be described in the same way as before, viz. by endowing each of them with a representative of its own. I would not call that one but rather the characteristic trait of quantum mechanics, the one that enforces its entire departure from classical lines of thought. By the interaction the two representatives [the quantum states] have become entangled. "

[Telos]

Yes, knucklebrain, you're exactly right.

What do you think? Is it intellectually responsible to observe instances like those and conclude that their are extra dimensions?

[Rob]

I dont think there are many other possibilities than another dimension! It does seem to prove it.
Fascinating that all three seemed to be entangled together.
Beavis - entangled objects act as single atom, thats kinda the definition of a superconductor, so I dont think you can seperate atoms from the whole of each "macroscopic device" like that.
First step to a quantum entangled trasistor if they are right! That would rock. I'm suprised they didn't mention the communication aspects of entanglement, I think that should really be our first goal.

Rob

[Telos]

I'm suprised they didn't mention the communication aspects of entanglement.

In my visit to science forums, I often see people joking about new agers think entanglement as anything to do with communication.

Entanglement is instantaneous and requires no transfer time. Therefore, there is no communication. Nothing is sent and nothing is received.

I'm sorry I didn't bookmark those pages, but I hope I shed some light on your question.

[Rob]

meh? Are you arguing semantics with me?

If you had two entangled devices you could affect one and see the effects on another. This would presumably work both ways. Call it what you want, I call it a new form of communication. Same principle in a superconduction computer, just smaller distances.
It would be a shame if the engineering requires getting things to superconducting cold, I've been thinking of ways around this for some time.

Rob

[Telos]

No, I'm not! I'm just telling you what I heard.

I don't claim to know QM (although I am earnestly trying everyday). But it seems like almost everything I've read outside of a new age book or forum says that entanglement is truly awful for communications purposes. I recall someone on the Discovery Science Channel very casually dismissing it, "most people confuse entanglement with communication, but that's really not what it is," and they fail to elaborate.

I wish I knew it better, but as far as I understand it, when things become entangled, it's like they literally become the same thing.

Instead of being a new form of communication, quantum entanglement seems to eliminate the need for communication in the first place.

What other reasons do you think no scientists talk about the communication aspects of entanglement?

[Edit: sorry I mentioned it... I'm not qualified to talk about it nor do I have referable sources to back it up.]

[-lines-]

Was reading a Scientific America, or one of those other scientific magazines, one day and it was talking about entanglement. Said that they managed to get five particles/somethings/whatever-they're-called entangled with 2 pairs and a fifth somehow hooked into the mess. They said it was the minimum needed for error correction (not sure that was it though), and were talking about the possiblilities of using it with computers, since it would allow instant communication between the two pairs because one has the same properties or whatever of the second pair.

Sorry that I can't be any more specific, I read it a couple of months ago. I'll see if it's still in the college library though and will throw you an update.

[Rob]

LOL Telos sorry if I sounded harsh I can be quite short cant I? Oh well!    

The guy on discovery science is aahhh badly mistaken IMO. The only issue is forming remote entanglement ie well removed from the local meissner field. Probably need to use resonance (perhaps scalar). I dont see any major theoretical issues with this, could be wrong, but that makes it an engineering problem - lucky, I'm an engineer  
But you are right saying its like they are only one atom! - within the actual entangled superconducting bits there is no "communication", but the devices which utilise these parts are still remote, and are still effectively in communication through the superconductors. Like connencting them with a wire of 0 distance, the hypothetical wire is still a connection.

Entangement has the potential to pretty much annihilate the phone network industry (think peer to peer mobiles, and then think of what the ensuing next gen internet would be like....tasty!!!). Conversely, quantum computers are an extension of computing technology and wont destroy any markets. Maybe thats it. Or maybe he didn't mention it because thats already thought of, wasnt the thrust of the article?

So! You got any leads for getting around the temperature issue? I'm thinking ORMUS or magnets might help.

As an aside, a friend was telling me of the theoetical research which is taking this phenomenon and going to the next level - like collective entanglement physics. He was saying that they found the entanglement spreads out in waves, and how everything is thus connected (oh and similarly think big bang, not that I put any faith in that theory any more, red shift disproven, but hey). Sound familiar???!!!!!!!!??!!?! Even karma is often described as a wave that flows out on the world and bounces back on you.
I am also in the process of reading a book which seems to be taking superconducting properties as the link between the micro and macro world, and going on the derive maxwells equations (ie the basis of electromagnetics   ). Very impressive.

Lines - please do keep us updated!

adios

Rob

[Psan]

Entanglement has the potential to pretty much annihilate the phone network industry

What if the telecom industry adopts this new tech? Fortunately engineering is not a religion.
Peer to peer sounds like a possibility. If you want to receive calls from any of the guys in the city, you'd need a switch.

[Telos]

Inguma, I've reached the point in Brian Greene's "Fabric of the Cosmos" when he explains how there is no communication (effective or otherwise).

Is there any way that, by measuring the spin of the left-moving and the right-moving photons about some given axis, we can send information from one to the other? The answer is no. Why? Well, the output found in either the left or the right detector is nothing but a random sequence of clockwise and counterclockwise results, since on any given run there is an equal probability of the particle to be found spinning one way or the other. In no way can we control or predict the outcome of any particular measurement. Thus, there is no message, there is no hidden code, there is no information whatsoever in either of these two random lists. The only interesting thing about the two lists is that they are identical – but that can't be discerned until the  two lists are brought together and compared by some conventional, slower-than-light means (fax, e-mail, phone call, etc.). The standard argument thus concludes that although measuring the spin of one photon appears instantaneously to affect the other, no information is transmitted from one to the other.

Given the random and unpredictable nature of measurement upon one of the entangled particles, I don't see how we could treat it as a wire of 0 distance. We do not know beforehand what behavior the particle will take after measurement, just that it will be correlated with its partner.

[Rob]

Yes it is rather tricky to affect and record in real time the spins of entangled particles, but any communication device would likely use some form of more macroscopic entanglement, eg as mentioned using superconductors. And yes the tests you mentioned use random events which correlate, but that by no means means that entanglement is limited to random particle spins - it obviously isn't, as proved by the first article you posted.

The only issue is whether the process of communication itself would break the entanglement (observation=alteration, on the quantum level, but with superconductors...?), however the article indicated this was not the case, since they were still observing the superconducting state using microwave pulses. The article you posted then went on to say that they were going to experiment with other ways which would show how robust the process is to interference:

The researchers obtained evidence of the entanglement indirectly, through the use of microwave pulses that probed the Josephson junctions; future experiments will seek to directly control the junctions and obtain evidence more directly

Whereas other groups have already shown it is robust enough.

I find it most curious that you post an article whose basis seems to rely on using entanglement for communication, and then you go on to argue with me that entanglement cannot be used for communication!!  

Of course I may be utterly wrong, but I await convincing  

I would like to suggest you try to disprove yourself, rather than trying to disprove me. Philosophically, it is impossible to prove a negative, but just one positive results of communication using entanglement is enough to disprove whole gaggles of theorists works that entanglement cannot be used for said purpose.
The patent office is useful for this purpose (see "description"):

http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=/netahtml/search-adv.htm&r=23&f=G&l=50&d=PTXT&p=1&S1=((entanglement+AND+communication)+AND+quantum)&OS=entanglement+AND+communication+AND+quantum&RS=((entanglement+AND+communication)+AND+quantum)

Here, he seems to be using another cunning way around the problem - that is, using a large mass of entangled photon ejections.
There really is tons more. I just ran across a reference in Nature to forming entanglement over remote distances, so that objection is now also invalid. But I'm sure you can find this stuff out for yourself, right?...

Rob (One Who Does Not Believe In The Impossible!!!!!)

[Telos]

Inguma, I thought the article I linked to was about quantum computers, not quantum communication. In order to perform a quantum computation, I thought it was necessary to have entangled objects, so that you use one as an input device and another to receive output.

But my knowledge is severely limited. Thank you for that link... interesting.

[Telos]

Whoa it's been a while for this thread, but I think someone explained that entanglement isn't communication rather well at PhysicsForums.

http://www.physicsforums.com/showthread.php?t=124883

We have not experimentally observed information transfer by quantum entanglement, or anything that might suggest it to be possible. In fact, there are strong no-go theorems against it - basically nonlocal or acausal communication would violate Special Relativity. (In short, communication is a causal physical process, hence it is limited by the speed of light.) This does not contradict the usual formalism, in which certain mathematical objects appear to travel FTL, because they are emphatically not observable!

The confusion about "information transfer by entanglement" is probably because there are communications protocols, involving entanglement, but not as an information channel (which we believe it cannot be). In short, if you have an entangled pair of qbits between users A and B, and also a supplementary communication channel between them (classical), then A and B can communicate securely by a mixture of classical communication and operations/measurements on their qbits. Example: they share a pair of entangled spin-1/2 particles, and A performs an operation on his/her qbit, then sends a message to B with instructions which basis to perform a measurement in, to "read" the message. The actual speed of information transfer is limited by the classical channel; however, an eavesdropper with access only to this and not the entangled qbits, cannot possibly decipher it - hence secure communication! (we hope) This is a frequently-discussed topic (related to quantum teleportation) and may explain the common confusion about this being "information transfer" - which it is not, sticking to standard terminology. Usually we talk about "correlations" between the states of the entangled qbits in different places and times.

Isn't QM fun?

[interception]

QM is indeed fun. Exercise for the old cobwebs.

Too bad I don't understand it.

So, the entanglement phenomena can be likened to the two ends of a single sheet of folded paper appearing to be two separate objects to a two dimensional entity? When in fact it is the same object in a higher dimension. Not the best analogy, I know... I'm trying though.

And further more: entanglement in and of itself has nothing to do with communication, but one CAN communicate by utilizing the entanglement phenomena (with seemingly unbreakable security) as long as the actual channel used remains classical?

[Telos]

So, the entanglement phenomena can be likened to the two ends of a single sheet of folded paper appearing to be two separate objects to a two dimensional entity? When in fact it is the same object in a higher dimension.

I don't think so. The only time I ever hear that folded sheet analogy is for wormholes. And wormholes don't travel through extra dimensions, but through a shortcut resulting from the shape of space.

Also, entanglement doesn't require extra dimensions either. Someday I'll go back to school for this stuff...

entanglement in and of itself has nothing to do with communication, but one CAN communicate by utilizing the entanglement phenomena (with seemingly unbreakable security) as long as the actual channel used remains classical?

That looks about right.