Somebody alert Jeff Goldblum

January 29, 2009 5:11 PM

Scientists from the University of Michigan and the University of Maryland have managed to teleport information from one isolated atom to another over a distance of one meter, without it ever crossing space. Here's how they did it.

You can also read the full abstract here, for those with a subscription.

Previous experiments with teleportation have been made:

Physicists teleport photons over 600 meters.

Scientists teleport photons over 89 miles.

Scientists teleport information from one atom to another with the help of a third one, albeit over a much smaller distance.

The latest experiment is the first succesful teleportation of a qubit - a unit of quantum information - between two widely separated, charged atoms without crossing space.

posted by Marisa Stole the Precious Thing (44 comments total)

Sorry Stross, your FTL communication gizmo ain't real quite yet:

Currently, only about one out of every 100 million attempts results in a successful entanglement, though Olmschenk says this rate could be significantly improved.
posted by GuyZero at 5:21 PM on January 29

Here's how they did it.

Fucking MAGIC.
posted by boo_radley at 5:23 PM on January 29 [3 favorites has favorites]

Any sufficiently advanced technology is indistinguishable from magic.
posted by troy at 5:24 PM on January 29

Sorry Stross, your FTL communication gizmo ain't real quite yet

This being a science thread, I actually only glanced into this thread to see how many comments elapsed before someone said "Nuh-UH!!"

Even I didn't expect it to be the very first one.
posted by hermitosis at 5:31 PM on January 29 [1 favorite has favorites]

Oh come on. It's fine science and I am, at worst, merely chiding Mr. Stross for having an idea that's too good for the average sci-fi story. The idea of using entangled atoms to achieve FTL communication was the conceit he used in Iron Sunrise and it's prequel (which I haven't read). I'm not actually mocking the scientists who have much more realistic expectations about what they're going to achieve versus a science fiction author.
posted by GuyZero at 5:35 PM on January 29

When everyone complains about not having the cool flying cars that we were all promised in the 50s, I think about things like this.

They teleported an atom. An atom! Scientists are officially proud to have transported something that we cannot even see with the naked eye.

And of course, it's a huge advance and it is the start of something cool, don't get me wrong.

It's just the fact that starting so small really sends home the message that those flying cars were never going to come right after the 'invention' (well, so to speak) of the car itself because it takes so many, many baby steps to get to what we all expect.
posted by librarylis at 5:37 PM on January 29

It is important to understand that this is quantum information, not classical information, being sent. The salient detail about quantum information is that it is unknown. It is also random. Thus you could never use this as a fancy telegraph because you can only send random unknown messages.
If you are thinking "that's useless" you are paying attention. It turns out that there are some special ways to make use of this, but they are not especially obvious. Calling this "teleportation" is misleading.
posted by Osmanthus at 5:39 PM on January 29 [2 favorites has favorites]

Any sufficiently advanced technology is indistinguishable from magic legerdemain.

Who knew?
posted by niles at 5:42 PM on January 29

I think you would use this in combination with quantum computing where you get the output in qubits. So you have massively parallel quantum computing with a teleporting output step. The sexiest application of quantum computing is factoring numbers which has direct application to cracking cryptography. More at Quantiki, the quantum computing wiki.
posted by GuyZero at 5:49 PM on January 29

The salient detail about quantum information is that it is unknown. It is also random. Thus you could never use this as a fancy telegraph because you can only send random unknown messages.

When Alice and Bob finally have a lovechild, this is the medium over which they would send the announcement.

For some reason, I imagine Charlie as knowing the name of the baby or its weight, but not both.
posted by nicething at 5:51 PM on January 29 [14 favorites has favorites]

Calling this "teleportation" is misleading.

From the abstract:

Quantum teleportation is the faithful transfer of quantum states between systems, relying on the prior establishment of entanglement and using only classical communication during the transmission. We report teleportation of quantum information between atomic quantum memories separated by about 1 meter. A quantum bit stored in a single trapped ytterbium ion (Yb+) is teleported to a second Yb+ atom with an average fidelity of 90% over a replete set of states.

In other words, the people who conducted this experiment describe what happened as "teleportation". I'm curious as to why you think this is misleading, and what term you consider more accurate.
posted by Marisa Stole the Precious Thing at 5:52 PM on January 29

"They teleported an atom."-librarylis

No, they did not teleport an atom. They transfered quantum information from one atom to another different atom.

GuyZero: your first message seems to imply that the reason FTL communication doesn't work "yet" is that untanglement is only successful one in 100 million times. This is wrongheaded. This method can *never* be used for FTL communication! Not even one bit ever.
posted by Osmanthus at 5:53 PM on January 29

I wish these guys would call it something else, since "teleportation" only gets the science "journalists" all worked up. But then they (the scientists...and the "journalists" I guess) wouldn't get as much funding. And the cycle of hype continues.
posted by DU at 5:55 PM on January 29

*facepalm*

I'm going to stick with retelling Dane Cook jokes from now on.
posted by GuyZero at 6:00 PM on January 29

In other words, the people who conducted this experiment describe what happened as "teleportation". I'm curious as to why you think this is misleading, and what term you consider more accurate.

"teleportation" was the coin termed by the physicists that laid out this protocol. it is misleading to the non-physicist public in the sense that there isn't a transport of matter in the star trek sense. a less confusing term might be "transportation of quantum state."
posted by alk at 6:05 PM on January 29 [1 favorite has favorites]

GuyZero, it's a little misleading to describe his material as "jokes".
posted by cortex at 6:07 PM on January 29 [6 favorites has favorites]

It's also misleading to describe my material as "jokes" so it evens out.
posted by GuyZero at 6:08 PM on January 29

Marisa: Physicist often use colorful language to describe things. For example, they use words like "charm" and "strange" to describe properties of quarks. Most people would not actually be so confused to think that a particle can be charming.

However, using the word "teleportation" in this context is confusing people. They title of this post makes a reference to the movie "the fly" which is about teleporting people from place to place, and someone has mention faster than light communications. This phenomenon has nothing to do with those two ideas.

Maybe they should call it 'non-local coherence' or just 'flooblejuble', a new word for a new idea :D
posted by Osmanthus at 6:10 PM on January 29

However, using the word "teleportation" in this context is confusing people. They title of this post makes a reference to the movie "the fly" which is about teleporting people from place to place

And the language of the post explains precisely what happened in the experiment - that quantum information was transfered from atom to another. The reference to The Fly was what is known in layman's terms as a joke.

If the charge of "misleading" is being leveled at the actual physicists, though, then I suppose I misread you.
posted by Marisa Stole the Precious Thing at 6:14 PM on January 29

Quantum teleportation will never transmit information faster than light, period.

Imagine Alice wants to teleport a qubit Q to Bob. Alice & Bob require an entangled pair of bits A & B, which must be transported physically in advance. Alice then measures A & Q in an entangled basis, giving her 2 classical bits, which she sends to Bob. Alice's measurement has destroyed both A & Q, collapsing them into some entangled state, but also moved the specific coefficients for Q over to B in one of four ways. Bob can preform one of four unitary operations to convert B into the original Q.

Alice & Bob have thus (a) carefully transported one entangled pair in advance and (b) transmitted two classical bits, all to transfer one quantum bit. So the are limited not just by the speed of light and 1/2 their channel capacity, but also their foresight and shipping capacity.

I suspect we will one day "teleport" humans without all this mess, one day after "humans" no longer think using meat. You can easily travel at the speed of light if you exist only as software & classical data.
posted by jeffburdges at 6:14 PM on January 29 [1 favorite has favorites]

Goat butts against the edge... and his horns become entangled.
posted by Durn Bronzefist at 6:22 PM on January 29

I think the main application, GuyZero, is unsnoopable one-time-pad like encryption. A classical one time pad can itself be snooped upon in transit, letting a spy Eve read the message secretly. But Eve cannot snoop upon the entangled "pad" state of A & B without Bob noticing. Also, the two classical bits contain no information about Q, only about the collapse of A & Q together.
posted by jeffburdges at 6:26 PM on January 29 [1 favorite has favorites]

But if you're going to carry around entangled atoms, why not just carry the pad?
posted by GuyZero at 6:30 PM on January 29

to expand on what osmanthus was saying, a very rough explanation of why an entangled state can't be used to transmit information goes along these lines:

we can create an entangled state of two particles that each take on values of "up" or "down" with equal probability. the state can be such that if Alice measures her particle to be "up" Bob will also measure his particle to be "up," and same for "down." this is the spooky action at a distance of the einstein-podolsky-rosen paradox, it shows that quantum mechanics is nonlocal.

however, when Alice is performing her measurement, she can't control whether her particle is measured to be "up" or "down" -- it's random. so although Bob will know what state Alice's particle is in if he performs a measurement, the state is random and can't be used by Alice to transmit part of a telephone call. hence the no-communication theorem.
posted by alk at 6:31 PM on January 29

nk there is any reason to

What in the world. How did I get into this thread? I was over on...Ah hell I better scan the computer.
posted by Kronos_to_Earth at 6:37 PM on January 29 [2 favorites has favorites]

The idea of using entangled atoms to achieve FTL communication was the conceit he used in Iron Sunrise and it's prequel (which I haven't read).

To be fair to the rest of the genre, it's shown up in a number of stories (I think Walter Jon Williams has also used it, for example). As jeffburdges points out, none of the things that physicists actually think entanglement can be used for include FTL communication; I think these SF stories usually assume some kind of new physics that allows the collapse of the entangled state to be observed, or something.
posted by hattifattener at 6:47 PM on January 29

The salient detail about quantum information is that it is unknown. It is also random. Thus you could never use this as a fancy telegraph because you can only send random unknown messages.

I think you've just explained YouTube comments...
posted by Dark Messiah at 7:00 PM on January 29 [1 favorite has favorites]

But if you're going to carry around entangled atoms, why not just carry the pad?

Because although in a technical sense, no information was sent FTL (due to the effort of shipping the atoms), in a practical sense, there was - events that happen in location A can be communicated instantaneously to location B. The set-up time is reasonably irrelevant.

In the same way, I can talk to someone across the globe near-instantly, because of the effort that's gone into setting up a global telephone grid - that effort doesn't actually impact the lag of my calls.
posted by Lemurrhea at 7:38 PM on January 29

Sweet. I have two questions I hope someone can explain to me:

1. If entanglement only works 1 out of 100 million times, how do we know that the information is actually being quantumly transmitted... and that it's not just a random coincidence that they have the same measured value.

2. What's really the deal with measument collapsing qubits? Surely quantumness doesn't "know" it's being measured, so I can only assume this description is a metaphor for a really complicated thing that is actually occuring... but what's actually happening? Is the another metaphor to help me understand better?
posted by the jam at 8:18 PM on January 29

the jam: Uncertainty Principle

Heisenberg got pulled over for speeding. The cop says "Do you know how fast you were going?" And Heisenberg says "No, but I know exactly where I am."
posted by niles at 8:35 PM on January 29 [1 favorite has favorites]

Wake me when Scotty can beam me up.
posted by shoesietart at 9:09 PM on January 29

Wake me when I don't have to go across the street in sub-zero temperature to get a Coca Cola. C'mon, Coke. Beam it right to my MOUTH.
posted by Astro Zombie at 9:16 PM on January 29

Also, I love the fact that "beam me up" is a proper command on Star Trek. YOU DON'T ACTUALLY GO UP ON A BEAM OF LIGHT, KIRK!
posted by Astro Zombie at 9:18 PM on January 29

Currently, only about one out of every 100 million attempts results in a successful entanglement, though Olmschenk says this rate could be significantly improved.

I don't know. If we beamed 100 million people through a teleporter device and only one person managed to get through, I'd still be pretty fucking impressed.
posted by Blazecock Pileon at 10:34 PM on January 29

I'm grasping for some kind of Space Hitler reference here, but I can't quite put it together.

"You know who else will have been beaming 100 million people through a teleporter device?" It just doesn't work.
posted by cortex at 10:48 PM on January 29 [1 favorite has favorites]

Because although in a technical sense, no information was sent FTL (due to the effort of shipping the atoms), in a practical sense, there was - events that happen in location A can be communicated instantaneously to location B.

I think you have it backwards. In a technical sense, there is communication— “spooky action at a distance”. In a practical sense, though, there is no communication, since there is no way (even in theory) to use this to actually transmit classical information (like news headlines, say) faster than light.
posted by hattifattener at 11:18 PM on January 29

Any technology distinguishable from magic is insufficiently advanced.
posted by Faint of Butt at 3:20 AM on January 30

Marisa Stole the Precious Thing, you're right that the physicists working on these projects refer to the process as "teleportation," but the guy who came up with the phrase essentially admitted that he called it that because it sounded cool and to get press. Think about it from another perspective: what's being transmitted is just information (admittedly, a lot of information), but we don't generally think of e.g. a telephone call as "teleporting" our voice.

Jam: What's really the deal with measument collapsing qubits? Surely quantumness doesn't "know" it's being measured, so I can only assume this description is a metaphor for a really complicated thing that is actually occuring... but what's actually happening? Is the another metaphor to help me understand better?

A quantum state actually does "know" that it's being measured, in the sense that its physical behavior is different before and after a measurement takes place. Explaining how this happens is a major problem in interpreting quantum theory. For obvious reasons, this question has a lot of philosophical implications, and there's a great article up at the Stanford Encyclopedia of Philosophy.
posted by voltairemodern at 8:42 AM on January 30 [1 favorite has favorites]

If we beamed 100 million people through a teleporter device and only one person managed to get through, I'd still be pretty fucking impressed.

Beam 'em all, let the odds sort 'em out?
posted by Atom Eyes at 9:06 AM on January 30 [1 favorite has favorites]

Oh this is old news. I've been sending and receiving quantum letters from my Future Self for years now. Due to the nature of quantum information, we don't open the letters for fear of creating some kind of entanglement-wave-form collapse that turns one of us into a small village in Devon or something. But, as always, curiosity got the better of me. I fired up the Quantum Information Interpreter (My Future Self sent to me for Christmas, which I'm told is in July now) and opened the first letter.

Right in my face. Large as Life. Tubgirl.

Man, when did become such a dick?
posted by The Whelk at 2:30 PM on January 30

when did I*

And I've ruined yet another punchline.
posted by The Whelk at 6:11 PM on January 30

alk (or anyone for that matter), I know that hidden variable theory doesn't hold, but I still don't understand why. Why isn't it true that the state was simple set and not measured when the two particles were in contact? (It's one of the last bits of a layman's version of quantum mechanics that I don't get and believe I can understand)
posted by Hactar at 6:51 PM on January 30

Try as hard as I might and despite considerable interest on my part, these articles end up translating as: "SCIENTISTS DO TECHNICAL THINGIES. THEY ARE HAPPY ABOUT IT."

Well, go scientists! I'm happy that you're happy! You just... keep on doing that... that whatever. It sounds really awesome!
posted by Scattercat at 4:06 AM on January 31

Hactar: I don't claim to really understand it either, but the thing you want to read up on is Bell's inequality and possibly the Aspect experiments (which looked for violations of Bell's inequality). The Baez link there spends a while explaining background; it starts to talk explicitly about nonlocality about halfway through. For experimental support, see (eg) this. Experiment is still whittling away at possible alternatives (see eg the Nature article I linked in my last comment).
posted by hattifattener at 1:03 PM on January 31