Einstein's 'Spooky Action' Has Been Demonstrated On a Massive Scale For the First Time (sciencealert.com)

schwit1 shares a report from ScienceAlert: For the first time, scientists have managed to show quantum entanglement -- which Einstein famously described as "spooky action at a distance" -- happening between macroscopic objects, a major step forward in our understanding of quantum physics. Quantum entanglement links particles in a way that they instantly affect each other, even over vast distances. On the surface, this powerful bond defies classical physics and, generally, our understanding of reality, which is why Einstein found it so spooky. But the phenomenon has since become a cornerstone of modern technology. Still, up until now quantum entanglement has only been demonstrated to work at the smallest of scales, in systems based on light and atoms, for example. Any attempt to increase the sizes has caused problems with stability, with the slightest of environmental disturbances breaking the connection. But new research changes all of this, by demonstrating that this "spooky action" can indeed be a reality between massive objects. We're not talking massive in the black hole sense but in the macroscopic sense -- two 15-micrometer-wide vibrating drum heads. And the next step will be to test whether those vibrations are being teleported between the two objects. The research has been published in the journal Nature.

Comments

News to me

[Anonymous Coward]

Entanglement is a cornerstone of modern technology? Say what?

"Massive" scale?

[UnknownSoldier]

Massive is relative.

15 micrometer is only 0.015 mm. Massive would be 1,500 meters.

0.015 mm is massive compared to 10^-10 m.

Context matters.

Re: "Massive" scale?

[Presence Eternal]

I think that's something like 60 times larger than modern transistor architecture.

Given we're used to entanglement involving single atoms, it is astonishing in size.

Re: "Massive" scale?

[cb88]

technically we have the capability to assemble single 1nm transistors since 2016... you can fit alot of transistors in 1um even at larger scales. I wonder what happens though when you entangle two circults.

http://newscenter.lbl.gov/2016/10/06/smallest-transistor-1-nm-gate/

Re: "Massive" scale?

[Lanthanide]

Entanglement is poorly understood. You don't "change one and the other changes".

Entangled particles vibrate/spin/whatever the same way. You don't know what that way of movement is until you measure it. When you measure A and discover it to be spinning clockwise (or whatever), then you also know that B is spinning clockwise. Both A and B were spinning clockwise from the time they were entangled, there is no "change" involved, just the fact that measuring the spin of A lets you also know the spin of B.

The bottom line is you CAN'T use this to transmit information instantly across distances: if it were the case that you could cause B to spin the same way as A by changing A's spin, then you could transmit information. That's not how entanglement works.

Re: "Massive" scale?

[HiThere]

Sorry, but Bell's Theorum only rules out local hidden variables. Non-local hidden variables are still within the bounds of the theory. But they're a bit weird, as they're non-local in time as well as space. I don't think the theory puts a bound on *how* non-local they can be, but a hypervolume of light years would be difficult to test. (OTOH, I'm no expert in this area. I believe that Boehm thought they were global rather than just non-local...but that was decades ago, and things may have been found out since then. OTOH, perhaps it's really implied by the theorum.)

Still, my favorite interpretation is EWG multi-world rather than hidden variables. For parsimony I add a supposition that I can't justify which is that in addition of the state space transitioning to all possible futures, it also arrives from all possible pasts, giving a lattice rather than a tree. I've got a vague feeling that this may determine the existence and strengthening of dark energy since all the pasts still exist in the hypervolume of the universe. You just can't go into the past because all of your particles have an inertial velocity along the time axis resulting from the big bang. If this *can* be made sensible, somebody much better at that kind of math than I am would need to tackle it. But it explains the rotation of the space-time axis as you accelerate near to the speed of light, or at least I think it does. I'm not quite clear how many dimensions this idea of the universe would require, but I'm sure it's less than the 16 that were used in deriving relativity, so it could probably fit into the same framework.

Re: "Massive" scale?

[ras]

In most ways it's not different. All these "entanglements" are just the basic laws of physics in action. So for example spin is conserved, so if two photons are created and speed away in opposite directions the laws of physics their spins must add up to 0. Therefore you measure the spin of one as 1, the spin of the other must be -1.

The issue as the physicists see it is a quantum variable is doesn't exist until it's measured, where "doesn't exist" means can have no effect on the universe. Although instead of "doesn't exist or has no value" they like to say it is a superposition of all possible values. Another way of saying the same thing is the particle has no idea what it's quantum values are because if it did it would behave differently. The classic example is the double slit experiment, where a photon very confused about where it is and forms an interference pattern. But if you measure where it is before it gets to the slits so it (and you) know the values of quantum variables, the pattern disappears.

The point is, before you measured it the spin on your photon didn't have a value. And that's true for it's entanglements partner too. Then you measure it and now you know. But it's entangled particular also knows its spin at the same instant, and starts behaving like it does. (Because if it didn't the laws of the universe would break down, eg charge or momentum wouldn't be conserved.) But if it's outside the light cone how could it know what the value it must take on to so the laws of universe aren't broken? It can't, so it must be spooky action at a distance.

The term "local hidden variable" is an explanation for how this happened. It means the photon knew all along what's spin was, but it was cleverly hiding it in this hidden variable. The key point here is it's value was computed at the moment of entanglement. It was hidden from then on until you measure it, but the value was agreed upon when the particles were entangled, and entanglement always happens when they are together, communicating. Global hidden variable is another explanation - it means the whole universe knew, which when you think about is means there is communication fast than light, because otherwise how could it be "global"?.

The local hidden variable sounds like the simplest explanation. The original reason said they said is doesn't work is Bells inequality. It may be still only be Bells inequality - I don't know if anybody has actually seen the double slit effect disappear for an entangled photon when it's mate is measured. I hope there is something more convincing now, because Bells inequality is a subtle argument.

It arises because quantum values are distinctly weird. Take spin for example. In the classic worked, you can look at something spinning and see what axis it is spinning around. In quantum world you can't do that. All you can do is point a ruler in a direction, compare the axis the photon spinning around to the direction this ruler is pointing. (You have to adopt an convention that describes the direction of spin - say ruler pointing up means spinning clockwise, down means counter clockwise on the same axis.) Worse when you point the ruler and ask the question, you force the photons spin to align with the ruler - so the measurement changes the thing being measured. But you do get something out of it - you are told whether the spin now (after it was changed by you observing it) agrees with the direction your ruler is pointing (up or down). So you get a single boolean answer, and that's all you get. But your measure is real and repeatable in the sense that if you do it again with the ruler aligned in the same way, you will get the same answer every time (because remember the spin is now aligned with your ruler). And if you measure it a again with the ruler pointed in the opposite direction (eg up instead of down), you will get the reverse answer every time. This sounds intuitively correct, and it's also somewhat intuitive that if you ruler isn't parallel it isn't entirely obvious

Re: "Massive" scale?

[GuB-42]

A very important part of the delayed choice quantum eraser experiment that is not always mentioned is the coincidence counter. And this is what prevents instant transmission of information.

The experiment is often described as "create a pair of entangled particles, do weird stuff and see where each particle go". But the truth is: most particles involved in the experiment aren't actually entangled, so if you just look at the detectors, the only thing you see is noise. You need the coincidence counter to tell you that two blips in the noise pattern are actually two entangled particles, but only after the two have arrived. That's the important part, you only know after the fact, you can't watch the thing happen.

You can't use a delayed choice quantum eraser to build a useful machine that allows you to transfer data faster than light. With the current understanding of physics, it is simply impossible, and no experiment disproved that. The "information traveled back in time" interpretation is just one of many.

Currently, science isn't settled on a correct interpretation of quantum mechanics. In fact, scientists have no fucking idea how all that stuff work. The maths work, experiments match predictions, engineers put it to good use, but we don't know how to interpret the results.

Re:"Spooky Action"

[thinkwaitfast]

It's just our 12-dimensional overlords toying with us.

Fundamental misunderstanding of entanglement

[Anonymous Coward]

>"In quantum teleportation, properties of physical bodies can be transmitted across arbitrary distances using the channel of 'spooky action at a distance'," says one of the team, Caspar Ockeloen-Korppi from Aalto University in Finland.

This is a fundamental misunderstanding of entanglement. It is not a mechanism for teleportation, it is a dual destination verification mechanism (ie. one must be opposite the other if they maintain entanglement). You cannot set the value at one end and have it appear on the other.

For us laymen

[raymorris]

For those of us who don't know enough to really understand it, we can think of it like a cat.
  You pull the cat's tail on one end, the cat meows on the other end. Quantum entanglement is exactly like that. Except there is no cat.

(The above is an old description of radio, often attributed to Einstein. Doesn't sound like Einstein's sense of humor, though.)

Clarification needed

[FranklinWebber]

I find the summary in great need of clarification. Let me attempt to clarify it in the hope that will be useful to other readers.

First, the linked article links to a much better summary written by one of the team members, Matt Woolley. I recommend you read it instead:
https://theconversation.com/ex...

Second, the summary conflates *mass* with *distance*. The experimenters claim to have entangled remarkably massive objects (compared to the mass of atoms, for example). But the summary says 'any attempt to increase the sizes has caused problems with stability' and that, taken literally, is not true. For example, here's an experiment from 1998 in which entanglement was maintained over a distance of kilometers:
https://en.wikipedia.org/wiki/...

Finally, the summary claims 'a major step forward in our understanding of quantum physics' but I doubt that. It sounds to me like a major accomplishment but one that *confirms* our previous understanding of quantum physics in more massive systems.

Re:Is this faster than light?

[Jeremi]

Or try this older-technology test, which is equivalent:

1) Obtain two empty boxes
2) Into the first box, place a red marble and a blue marble
3) Put on a blindfold so you can't see anything
4) While blindfolded, reach into the box with the marbles and take out one of the marbles, and put it into the other box
5) Close both boxes and seal them shut
6) Remove the blindfold
7) Mail one of the boxes to Alpha Centauri
8) When it gets there, open the box you didn't mail, and note what color marble is in it
9) Enjoy the "faster than light communication" -- you just "instantaneously" learned the color of a marble located four light years away!

Re:Is this faster than light?

[Cacadril]

Improving the analogy a little:

1. Get two WHITE marbles, each with the property that if you shake it, it will randomly turn blue or red.
2. Put the marbles in boxes and mail one box to Alpha Centauri. Wait until you know it has arrived.
3. Open your box and shake your marble, and watch it become red. Now you know that the other marble will turn blue, or already turned blue as your fellow Alpha Centauri scientist shakes or shook his marble. This is because of a law of nature dictating that the total number of blue and red marbles in the Universe must balance.

Nobody can tell in a meaningful way who shook his marble first. Depending on the velocity of the observer, it could be either one of you who "instantly" programmed the other marble to assume the opposite color. (This is the part that most people forget when describing the spooky instantaneous, FTL action at a distance.)

Remember once more, none of you had any control over what color your marble turned.

Anyone of you may instead paint your marble to force it into the color of your preference, but that breaks the quantum spooky action at a distance. If/when your fellow shakes his marble, it may assume any color. But your fellow won't know the difference until you tell him that you cheated.

If you later communicate with your fellow and learn that his marble turned the wrong color, it just means that the marbles failed to become properly entangled.