Instant Quantum Communication Is Near

fljmayer writes "In this experiment, researchers in Australia and Japan were able to transfer quantum information from one place to another without having to physically move it. It was destroyed in one place and instantly resurrected in another, 'alive' again and unchanged. This is a major advance, as previous teleportation experiments were either very slow or caused some information to be lost."

Comments

HU?

[ae1294]

Wait wasn't this impossible like a week ago?

Re:HU?

[gr8_phk]

Don't worry, no USEFUL information was transferred.

Re:HU?

[earls]

Hurray, networks and computers full of no USEFUL information!

Re:HU?

[davester666]

No. This has been possible to do for millennia. We've finally got around to actually attempting it.

Re:HU?

[ae1294]

What about porn? Can we use this to transmit porn at lighting fast speeds over an extended period of time and for massive profit?

Re:HU?

[stms]

Yeah I believe that's why they call it a breakthrough.

Re:HU?

[bill_mcgonigle]

Don't worry, no USEFUL information was transferred

Holy cow, they're broadcasting CNN on a quantum teleportation channel now?

Re:HU?

[jhoegl]

Sorry, you have reached your Quantum limit here at Comcast, you are now at 56kbps speeds.

Re:HU?

[Anonymous Coward]

Wow. That's like faster than Verizon Billing. Never thought I'd live to see this day.

Re:HU?

[ae1294]

Sorry, you have reached your Quantum limit here at Comcast, you are now at 56kbps speeds.

That's ok... I'll use my Quantum tunnel to the other universe.

Re:HU?

[oliverthered]

It's OK, I entangled it with the number on my betting slip and interfered with the slip between the result coming in and the clerk checking the slip

Re:HU?

[Anonymous Coward]

No, they're still working on it. For now it's just Fox News.

Re:HU?

[ColdWetDog]

Hurray, networks and computers full of no USEFUL information!

Could be useful for Facebook and Twitter.

Re:HU?

[c6gunner]

This is the kind of comment that gets you slapped with a trout.

Re:HU?

[Darinbob]

Through the magic of Slashdot, I will now attempt to transmit information forward through time! (Gentlemen, I bid you adieu!)

CAC 40 3908.58 +0.7% ; NIKKEI 225,9441.03 -1.21% ; FTSE100,5896.87

Re:HU?

[Anonymous Coward]

Nope...just FOX and HLN.

Re:HU?

[Thing 1]

I suppose it depends on how complex the trout is.

Re:HU?

[Anonymous Coward]

No, I think it was just one of Sarah Palin's tweets.

Re:HU?

[Gerzel]

Yeah fox news is coming in from the future. Problem is that it is the future of a completely different universe.

Re:HU?

[lymond01]

Oh. So they can only broadcast network TV?

Re:HU?

[ozmanjusri]

Could be useful for Facebook and Twitter.

MySpace Quantum Edition: Instantly more irritating.

Re:HU?

[Anonymous Coward]

"I'd like to superpose her Eigenstates... heh heh!"

Re:HU?

[tyrione]

Don't worry, no USEFUL information was transferred

Holy cow, they're broadcasting CNN on a quantum teleportation channel now?

It's a tough call, really. Which one really first landed on the quantum teleporation channel, FOX or CNN? I think we can safely assume FOX never started out with any USEFUL information.

Re:HU?

[narcc]

Hurray, networks and computers full of no USEFUL information!

The internet is almost there now.

Re:HU?

[Anonymous Coward]

I just got this nearly an hour in the future! *utterly amazed*

Re:HU?

[stardaemon]

Sadly, I think most of us will have to content ourselves by slapping him with the imaginary part.

Re:HU?

[TheRaven64]

If they really mean 'instantaneously', then it's a pretty major upset in our current knowledge of physics. If they mean 'at a speed less than or equal to the speed of light in a vacuum in a straight line', then it's still useful (maximum 42ms latency anywhere in the world), but has been thought to be possible for a while. If it really is instantaneous then there are going to be all sorts of fun causality-violating experiments to try...

Re:HU?

[Anonymous Coward]

The only thing that makes it seem possible this week is the very poor reading comprehension of the submitter.

Re:HU?

[MasterPatricko]

I'm afraid quantum non-locality is old hat; entangled particles really do seem to transmit information at faster than the speed of light. Its one of the reasons that quantum theory and relativity seem incompatible, and why Einstein ended up fighting quantum theory after helping invent it.

http://en.wikipedia.org/wiki/Bell's_theorem

Re:HU?

[MasterPatricko]

Note this is quantum information, not classical information. No-communication theorems seem to show that classical information cannot be transferred in this way.

http://en.wikipedia.org/wiki/No-communication_theorem

Re:HU?

[Anonymous Coward]

Does alien porn really turn you on?

Re:HU?

[bluefoxlucid]

Until you encode classical information into the affect of quantum information. [Bonus points for advanced use of 'affect', unless I got that one wrong...]

Re:HU?

[Anonymous Coward]

What do you do if assaulted by a man armed with a trout?

Counter with a tiger.

Re:HU?

[rgbatduke]

No, no, no. Phase velocity versus group velocity. You cannot transmit information faster than the speed of light in either quantum mechanics or classical mechanics. Phase velocity can be anything you like, but it is irrelevant. Group velocity carries information that can be decoded, and propagates at c (or slower) in both classical and quantum field theory.

No soup for you!

rgb

p.s. -- "affect" is what you put on like a social cloak when entering a room in a social situation, as in "he is so affected, he's totally bogus". "effect" is what causes produce. Effects propagating faster than the speed of light actual threaten the consistency of physics in a variety of ways. This, of course, isn't unthinkable -- all cards are on the table when formulating physical theories -- but so far there is no evidence that effects that carry information precede causes. OTOH, the propagators of physics generally can be formulated in advanced, retarded, stationary, and mixed expressions, and no physical results depend on which one is used -- the actual solution to the equations of motion involved is stationary in both quantum and classical mechanics and hence the dynamical solution is itself invariant, causality in the sense of past causing the future is an entropy-based illusion.

I wish everybody taught the Generalized Master Equation in quantum mechanics before they taught the EPR paradox. It would make life ever so much simpler if one learned that "wavefunction collapse" is an artifact of the thermodynamics of the measurement apparatus.

Re:HU?

[bluefoxlucid]

Yes but as a verb, "effect" and "affect" mean different things. My affects are my own, but to effect change I must do something intangible. The effect of an action is sometimes readily visible... affect seems to deal with the visible emotion or mood of something though.

Re:HU?

[Anonymous Coward]

The article doesn't make it clear if the information sent is useful or not :(

Re:HU?

[Anonymous Coward]

Yes and No

Re:HU?

[Anonymous Coward]

I am not a Physicist and definitely don't understand the Quantum or the Relative kind but assuming Relativity is correct, without implying Quantum is incorrect, wouldn't Galaxies sufficiently far apart in Space may also be far apart in Time such that they have their own Time and thus making instantaneous communication between the two a meaningless proposition?

I think "instantaneous" would require an Absolute Time, and sufficient Space Time separation between two objects would allow nothing other than Relative Time. Basically, how are going to determine the event as happening in two places simultaneously?

Re:HU?

[ae1294]

Does alien porn really turn you on?

Yes almost as much as Furry Hentai Porn....I also love Big Black COCK...

Re:HU?

[ae1294]

Yeah fox news is coming in from the future. Problem is that it is the future of a completely different universe.

So all of the stories are fact checked AND fair and balanced?

Re:HU?

[AP31R0N]

Yeah! Popular websites suck! Because I don't like them neither should anyone else.

Re:HU?

[Ol Olsoc]

Kansas has just passed a law against teaching about this quantum nonsense in schools.

Re:fix

[ae1294]

Sorry I'm posting from a quantum computer... And also not posting....

Physics

[BradleyUffner]

Isn't there some law of physics that says information can not be transmitted faster than the speed of light?

Re:Physics

[QuantumG]

Hint: the title is unrelated to both the summary and the article.

Re:Physics

[$RANDOMLUSER]

Yes. Yes, of course there is. Unfortunately, there is no law of physics limiting the scope of journalistic hyperbole.

Re:Physics

[icebike]

Not really.

Your post shows you have read neither the summary or the article.
And your cat is dead.

Re:Physics

[QuantumG]

I read the article 3 days ago when it was news.

Re:Physics

[BradleyUffner]

Not really.

Your post shows you have read neither the summary or the article.
And your cat is dead.

How so?

From TFA:

In this experiment, researchers in Australia and Japan were able to transfer quantum information from one place to another without having to physically move it. It was destroyed in one place and instantly resurrected in another, “alive” again and unchanged. This is a major advance, as previous teleportation experiments were either very slow or caused some information to be lost.

that suggests to me they are claiming to be able to transfer information faster than the speed of light.
They use the word "instant" to describe the amount of time it took to "move information". Information transmitted via light between any 2 points that are not occupying the same space always takes more time than "instant"

Re:Physics

[Americium]

Yes, it's in the details,I haven't read this article, but I assume it's similar to other methods than seem to invoke FTL.

  You can't be sure what state you have before you transfer it, and if you do measure it, it changes the state. Therefore, when you teleport the current state, the receiver can see what state it's in, let's say 0 or 1. But since the sender didn't know if it was a 0 or a 1, the information is useless.

Personally I think spooky action at a distance isn't spooky at all. Consider the time-honored classic of two electrons in a correlated state being shot out of some device. Assume they are entangled in such a way that when you measure one to be up, you instantly know the other is down. Physicists will say, how could the other electron possibly know this, instantly. But a very simple explanation is that the device always shoots 1 up, 1 down. Sure you don't know if it's up or down until you measure it, but that doesn't make it spooky at all.

The actual spookiness is in the details, like what if I now measure it's spin with respect to a different axis, the classical and quantum results differ then, but I cannot think of any practical application this provides us.

Re:Physics

[BradleyUffner]

Sorry IceBike. Thought you were replying to me, disregard the parent post.

Re:Physics

[Anonymous Coward]

Isn't there some law of physics that says information can not be transmitted faster than the speed of light?

Yes. The headline is incorrect. The experiment 'teleported' the quantum state of photons (but not the photons themselves, that is almost certainly impossible, or at least, grossly impractical) in a way that was much faster than previous experiments. But still slower than the speed of light.

Re:Physics

[$RANDOMLUSER]

No, no he's not dead, he's, he's restin'! Remarkable cat, the Norwegian Blue.

Re:Physics

[BradleyUffner]

Isn't there some law of physics that says information can not be transmitted faster than the speed of light?

Yes. The headline is incorrect. The experiment 'teleported' the quantum state of photons (but not the photons themselves, that is almost certainly impossible, or at least, grossly impractical) in a way that was much faster than previous experiments. But still slower than the speed of light.

To be fair to the headline, the text of the article mentions that the state was transmitted instantly, which implies speeds faster than light.

Re:Physics

[thegrassyknowl]

It wasn't my cat, but Schrödinger might be a bit miffed since he preferred it both alive and dead at the same time.

Re:Physics

[TexVex]

The actual spookiness is in the details, like what if I now measure it's spin with respect to a different axis, the classical and quantum results differ then, but I cannot think of any practical application this provides us.

Basically, the rate of correlation when measuring entangled things is a function of the orientations of the detectors. The only way to explain that is: 1> Assume that the universe is deterministic, so the entire future state of the system is known at the time of the event that creates the entanglement; 2> Assume that a change made to one member of an entangled pair have an instant effect across any distance on the other member of that pair.

Since entanglement and randomness are inextricably linked here, there's no way to use the effect to either foresee the future or communicate faster than light (and by extension, change the past). So you're right that there's no practical application for it.

It just raises some extremely thought-provoking questions about the nature of our reality.

Re:Physics

[JustinRLynn]

As they say, "A cat in any state is fine too."

Re:Physics

[blueg3]

As odd as it sounds, there's not actually any difference between teleporting "only" the quantum state of the photons and teleporting the photons themselves -- provide the state you're teleporting is the entire state of the photon. Quantum mechanical particles are entirely defined by their state; beyond that state, they're all the same. (Of course, this is counterintuitive.)

Still, while the state change technically is propagated instantaneously (a pair of entangled photons are sharing a single state, so changes in the state are "instant"), it's impossible to make any use of this (to transmit information, for example) without transmitting information via conventional means, which can be no faster than light.

Re:Physics

[Anonymous Coward]

That is only belived by a couple of physicists with no imagination and a need to be listened too. Einstein knew about instantaneous information transfer but he didn't understand it.

Re:Physics

[Anonymous Coward]

The thing I don't understand is why people care what state it's in -- if you can trap two quantum-entangled electrons & move one several miles away you have either instant or speed-of-light (I'm not sure which) -- and possibly private -- communication.

A simple solution -- connect old-style half-duplex modems to an electric or magnetic field generators/sensors. The modems will wiggle & sense the state of the electrons at an audio rate. Now send information from one modem, wiggling electron 1 to its quantum entangled electron 2 which wiggles at the same rate, is sensed & the audio fed to the other modem.

At least this is what the EPR (Einstein-someone-someone) experiment seemed to predict. It would be great to have cellphones without the need for cell towers, and the question about cell phone causing cancer would be moot :-).

Re:Physics

[bill_mcgonigle]

Physicists will say, how could the other electron possibly know this, instantly

Why would they assume that the electrons are separated? Because we perceive them that way?

Isn't it easier to assume that they're not separate entities and that we just don't know how the universe is put together than to assume that we understand the universe and there's a 'magical' force communicating across infinite distance?

Re:Physics

[Anonymous Coward]

Data is not "transfered" it is "teleported" so it's not faster than the speed of light it's just as two place at once

Re:Physics

[Dr Max]

How do you explain that when you change the spin of one you change the spin direction of the other aswell?

Re:Physics

[Fnkmaster]

This article is awful. Terribly written, incoherent and obviously inaccurate.

This sounds like an extension of previous quantum state "teleportation" via entanglement. These are interesting phenomena, but cannot be used to transmit information faster than the speed of light.

It's not really quite clear what the breakthrough is here. But I'm fairly certain it doesn't involve a group velocity (i.e. information transmission) greater than c.

Re:Physics

[Anonymous Coward]

That is only belived by a couple of physicists with no imagination and a need to be listened too. Einstein knew about instantaneous information transfer but he didn't understand it.

Bullshit. Lrn2science, kid.
  Einstein began with the hypothesis that the laws of physics must function the same for all observers. (A sane starting place, and one that's held true in our measurements from the largest galaxies to the smallest subatomic particles.)
  From that fell out the fact that light speed is the limit, and there is no universal frame of reference. There is no absolute rest (so nothing "stops" moving, except relative to other things) and no absolute time (so there's no "instant" except within the context of a reference frame.) and nothing moves faster than light.

  The problem for FTL proponents is that if an object or signal at one location, call it A, arrives at a distant location (B) before its own light arrives, then it will have arrived before it left in some reference frames. Sci-fi usually handwaves these reference frames away and tries to ignore their implications.
  However, if one returns the signal or object the way it came, it will now arrive before it departed in ALL reference frames, and causality is borked. Say hello to time travel, and the huge can of worms that it involves.

Re:Physics

[0123456]

How do you explain that when you change the spin of one you change the spin direction of the other aswell?

Two words: Transactional Interpretation.

The only spooky thing about 'spooky action at a distance' is that people think it's spooky. It's just a consequence of using non-relativistic quantum mechanics; you shouldn't be surprised that non-relativistic physics allows things to travel faster than light.

Re:Physics

[Anonymous Coward]

If he read neither the post nor the summary, then why would you assume he bothered checking the status of the cat?

Re:Physics

[TexVex]

What you are suggesting sounds like an ansible. This is a science fiction FTL communication device invented by Orson Scott Card. It's based on the idea of a trapped subatomic particle that has been split in two, while the resulting pair of particles remain permanently linked such that any change made to one is reflected instantly in the other no matter how much spacial distance separates them.

Quantum entanglement can be thought of as working like that, except that as soon as one of the split particles interacts with anything else at all in any way and the resulting change is "transferred" to the paired particle, that entanglement is broken.

Re:Physics

[Anonymous Coward]

The ansible is a lot older than Card, it's been a hokey SF trope since relativity was new.. The term "ansible" comes from Ursula K. LeGuin's "Rocannon's World" (thanks wikipedia).

The biggest problem with this whole thing is that you can't set the spin of the particles once they're entangled, and entanglement requires moving them next to each other - doing so breaks the entanglement. This means it can never be any faster a means of transportation than just writing your message down and carrying it to the destination.

  I wish we could slap all these awful science journalists and make them stop. But we might as well get used to it. My ansible just spat out a message from future-me that says we'll continue to get these stupid stories from now until the robot conquest makes human journalists an obsolete curiosity.

Re:Physics

[Anonymous Coward]

You know what's spooky? People with vast knowledge of physics, history and mathematics who still can't tell IT IS from ITS. Damn that apostrophe is POWERFUL mojo!

Re:Physics

[Xachariah]

And your cat is dead.

Maybe...

Re:Physics

[Anonymous Coward]

What happens if the cat in the box is a Cheshire cat???

Re:Physics

[Americium]

If you flip it after you make the measurement it doesn't do anything.

So you are suggesting to put in a spin flipper before you make a measurement. Does the entanglement still hold then?

Re:Physics

[c6gunner]

It wasn't my cat, but Schrödinger might be a bit miffed since he preferred it both alive and dead at the same time.

That's just something he came up with so he wouldn't have to explain death to his kids.

"Daddy, what's wrong with Mr. Whiskers?"
"Well, see, if we put him in this box ..."

Re:Physics

[Anonymous Coward]

No, there is no law for this. It is true that you cannot move matter or energy faster than the speed of light. Matter and energy are normally used to CARRY information, but information itself is not subject to this limit.

Re:Physics

[DigiShaman]

But it won't be a Cheshire cat once you open the box. Just ask Alice.

Re:Physics

[Anonymous Coward]

Laws are made to be broken.

Re:Physics

[Thing 1]

It just raises some extremely thought-provoking questions about the nature of our reality.

...and, how we can play with it.

Re:Physics

[Anonymous Coward]

Nope.

Re:Physics

[Anonymous Coward]

Isn't it easier to assume that they're not separate entities and that we just don't know how the universe is put together than to assume that we understand the universe and there's a 'magical' force communicating across infinite distance?

You win the fucking internet, sir.

Re:Physics

[Turnpike Lad]

It's impossible to transmit information faster than the speed of light because simultaneity doesn't exist.

Depending on your reference frame, event A might happen before event B, or vice versa. And since there is no rest frame, no one timeline is privileged above the others. The speed of light isn't just a universal speed limit, it places bounds upon causality itself. So when we talk about communication across interstellar distances, we're speaking nonsense: the idea that event A on Earth takes place at the same time as event B on Alpha Centauri just isn't coherent.

Re:Physics

[Anonymous Coward]

Basically, the rate of correlation when measuring entangled things is a function of the orientations of the detectors.

OK, so suppose I have two boxes and one ball. I put the ball in one of the boxes at random and mail one box to a friend in Australia and the other box to a friend in Japan. Then, when my friend in Japan opens his box, he "instantly" knows whether the ball is in the box in Australia. The information about the Australian box has instantly teleported from Australia to Japan, so to speak.

But what you seem to be saying is that if the box in Japan is opened from the top then there is always exactly one ball - which is either in the Japan box or the Australia box. But that if the box in Japan is opened from the side then there might be zero, one, or even two balls - neither box could contain a ball - or both boxes could each contain a ball.

With the classic double-slit experiment, the argument is that the quantum particle goes through both slits because of the way it interferes with itself at the detector (interference pattern). But can we do something similar with quantum teleportation: have my friends in Japan and Australia mail the boxes back unopened, merge the contents of the two boxes and show that the single resulting ball has been to both Japan and Australia?

Re:Physics

[MacGyver2210]

Shut up. You ruin everything.

Re:Physics

[TexVex]

With the classic double-slit experiment, the argument is that the quantum particle goes through both slits because of the way it interferes with itself at the detector (interference pattern). But can we do something similar with quantum teleportation: have my friends in Japan and Australia mail the boxes back unopened, merge the contents of the two boxes and show that the single resulting ball has been to both Japan and Australia?

Well, if the boxes were mailed back unopened and somehow merged back together, then the resulting "ball" would be unchanged from the original. It wouldn't matter if they went to another galaxy and back, if nothing ever interacted with them. That's the rub: things are only changed by measurement and what you describe is only two measurements: 1> Splitting the ball; and 2> Merging the split balls back into one. Like everything else, information is a conserved quantity. A qubit won't spontaneously flip.

Maybe you are asking something more like the following:

1> Beam a high-energy photon into a splitter
2> Two lower-energy entangled photons emerge. Their total energy equals the energy of the original photon. They are both traveling in opposite directions, with opposite polarization. However, we have no way of knowing the polarization or energy or direction of travel of either, until we measure one. They are entangled.
3> Both photons hit perfectly aligned equidistant mirrors and are reflected back, where they hit the same atom that split them, at the same time. 4> The splitter merges the two photons and emits a new photon, which you then measure.

So the question would be, what would be the characteristics of the final photon, right?

When the photons bounce off the reflectors, the reflectors recoil. This interaction exchanges some energy and spin. Some of the entanglement from the two photons is transferred to their corresponding reflectors and now those two reflectors share some of the information that the entangled photons carried. The result is a bunch of new entanglements. The mirrors now share some of the random unknown information that the photons used to share, while the photons are no longer fully correlated with each other and instead contain some information traded with the mirrors. So when the photons are merged again, the resulting photon contains some of the information from each of the two reflectors.

So I guess, yes, if you knew some identifying characteristics of the mirrors, then the resulting final photon would contain some information showing that it had interacted with both.

Re:Physics

[paiute]

Basically, the rate of correlation when measuring entangled things is a function of the orientations of the detectors.

OK, so suppose I have two boxes and one ball. I put the ball in one of the boxes at random and mail one box to a friend in Australia and the other box to a friend in Japan. Then, when my friend in Japan opens his box, he "instantly" knows whether the ball is in the box in Australia. The information about the Australian box has instantly teleported from Australia to Japan, so to speak.

But what you seem to be saying is that if the box in Japan is opened from the top then there is always exactly one ball - which is either in the Japan box or the Australia box. But that if the box in Japan is opened from the side then there might be zero, one, or even two balls - neither box could contain a ball - or both boxes could each contain a ball.

With the classic double-slit experiment, the argument is that the quantum particle goes through both slits because of the way it interferes with itself at the detector (interference pattern). But can we do something similar with quantum teleportation: have my friends in Japan and Australia mail the boxes back unopened, merge the contents of the two boxes and show that the single resulting ball has been to both Japan and Australia?

What if you have three boxes, you open one, then Monty Hall opens another one?

Re:Physics

[MarkRose]

Curiosity killed the cat. I guess quantum mechanics brought him back?

Re:Physics

[dgatwood]

As a non-physicist, I have yet to hear a good explanation for any useful means of turning faster-than-light travel into time travel, and every explanation I have heard sounds pretty absurd.

If an a cause triggers an effect somewhere else in a faster-than-light fashion, sure, an outside observer in some frame of reference might be able to observe it occurring before the cause. This happens any time that the outside observer is closer to the effect than to the cause. However, at no point does that observer observe the effect before the cause occurs. If that observer is, for example, five light years away from the effect and ten light years away from the cause, then the observer still observes the effect five years after the cause occurred.

Similarly, when we have observer A seeing a body B moving slower than the speed of light and a body C moving faster than the speed of light towards it (but slower than the speed of light relative to A), observer A will observe both body B and body C observing each other's past events in reverse chronological order from the order that body A observes them. However, they have still already happened from the perspective of each of B and C by the time either of the other bodies observes the event, so no causality is violated. And even if information could travel at an effectively infinite speed between B and C, this would still hold true because the near infinitely small time it takes information to travel from B to C would ensure that any information passed back to B would arrive later. If B is closer to A, it would appear to have been received by B after it was sent by B, but before it was sent by C. From another frame of reference the reverse might be true. The key to preserving causality is that there must not be a frame of reference in which both are true.

Could somebody please explain to me what I'm missing?

Re:Physics

[Dr Max]

A standing wave formed by future waves and waves from the past still seems a little spooky to me. However it seems there is still quite a bit of debate as to whether this accurately describes the situation. Thanks for the link.

Re:Physics

[i_ate_god]

wouldn't it be possible just to write some code to delay the display of a message if it came from the future to just one second after the first message was sent?

Re:Physics

[Jane Q. Public]

This is what bothered me about it, too. The words "destroyed in one place and instantly resurrected in another" clearly imply superluminal information transfer. And it gave me pause, because I am familiar with the theory that information cannot be transferred faster than light. Not 100% convinced by it, but familiar with it. I thought it was a good enough approximation, anyhow, for the present time.

So then I read that quantum experimenters -- who are clearly on the cutting-edge of physics -- are now "instantly" transferring information, which wasn't even given further notice in the article, and I thought "Wait, what? When did I miss THAT breakthrough?"

Re:Physics

[iris-n]

It's not really quite clear what the breakthrough is here. But I'm fairly certain it doesn't involve a group velocity (i.e. information transmission) greater than c.

You're right, it isn't. This article makes me sick. If people take shit like this seriously they can't be blamed for not being able to differentiate real science from quantum woo.

It's better to just ignore than try to correct it.

Teleportation is a real phenomenon, albeit a bit old. This is not their breakthrough. The breakthrough is doing it with a cat state (the name is a reference to Schrödinger's cat; this kind of state was inspired in it). These states are usually very fragile, and strongly entangled, hence the interest.

Also other breakthrough is doing it with the measurement of the number of photons and position. This is a promising technique, that I am personally working with at the moment to test Bell inequalities, because of its high resistance to noise. But I don't think it is very exciting to the general public...

Re:Physics

[torrin]

You sir, deserve a Guinness...

Re:Physics

[catmistake]

It wasn't my cat, but Schrödinger might be a bit miffed since he preferred it both alive and dead at the same time.

That's just something he came up with so he wouldn't have to explain death to his kids.

"Daddy, what's wrong with Mr. Whiskers?" "Well, see, if we put him in this box ..."

I doubt that... Schrödinger hated kids. But he hated cats more.

Re:Physics

[tonywestonuk]

Take a source of entangled photons.. It could emit one photon at 0 polarised (for vertically polarised), and one at 90 for horizontally polarised, in a continuos random stream of.... lets also imagine that this set of emitted photons are a bit stream. H for 0, and V for 90. It could look like this

HHVHVVVHVHHVHVHHVVHVVHVHVH -> stream of Photons
VVHVHHHVHVVHVHVVHHVHHVHVHV -> stream of entangled pairs

And lets finally say, that this emitter could be reset so the same bit stream could be sent time again. This is impossible, but, for the sake of argument, let say it could.

A detector at the other end, will detect if photons received are at 0 or 90, showing 'H' for polarised photons at 0, and 'V' for photons polarised at 90
So, the two received bit streams would be:

HHVHVVVHVHHVHVHHVVHVVHVHVH -> Photon
VVHVHHHVHVVHVHVVHHVHHVHVHV -> entangled pair

Nothing spooky so far?... Well, lets rotate the detector itself 90, so that photons arriving at 0, will be detected as 'V' and photons arriving at 90 will be shown as 'H'. The detector will continue to match the pair of photons, one as been a 'V' and one as been a 'H'., just the other way around.... Still no spookyness here.

VVHVHHHVHVVHVHVVHHVHHVHVHV -> Photon
HHVHVVVHVHHVHVHHVVHVVHVHVH -> Entangled Pair

Ok, rotate the detector so its set to 45, in between horizontal and vertical. The photons arriving at 0, will, at random, will have to choose, at random, a new polarisation. So, in classical theory, the bit streams should no longer correlate..... This is not the case.

HVVHVVHVVHVHHVHVHHVVHVHVHV -> Photon
VHHVHHVHHVHVVHVHVVHHVHVHVH -> Entangled Pair

Though the bit streams are different than they were emitted, yet they still correlate. This is the spooky part. the photon has to select H or V, when it gets detected. How is it possible that the entangled pair, 'knows' which orientation its partner was decided by its partner?

Its very weird. I personally think, that the partical we know as being a 'photon' or 'electron', isn't like a very tiny ball bearing traveling through space..... but, more like something else... If we think of particles having spin, and being able to detect them, then all this quantum weirdness appears.. Something else is going on. What that is, I have no idea, and neither does any one else..... But, quantum theory matches what we observe, it just doesn't make sense.

Re:Physics

[Americium]

Ok, rotate the detector so its set to 45, in between horizontal and vertical. The photons arriving at 0, will, at random, will have to choose, at random, a new polarisation.

Incorrect, not all the photons will get through, and any that do go through are now polarized at 45. Perhaps you were thinking about electron spin and the Stern-Gerlach experiment.

So, in classical theory, the bit streams should no longer correlate..... This is not the case. HVVHVVHVVHVHHVHVHHVVHVHVHV -> Photon VHHVHHVHHVHVVHVHVVHHVHVHVH -> Entangled Pair

No, this is not the case at all. If you do not know which axis to measure on you destroy the entangled state.

The spooky effect is that you do see either a quicker or slower dropoff than the cos^2(theta) for polarizers with these entangled state, I can't remember which (quicker/slower).

Re:Physics

[Americium]

I thought it did still hold, and that I was incorrect in my analogy, and it is kinda spooky. Anyone else care to chime in?

Re:Physics

[thegrassyknowl]

And a cat in both states is better: Zombie cat!

Re:Physics

[Anthony Mouse]

If an a cause triggers an effect somewhere else in a faster-than-light fashion, sure, an outside observer in some frame of reference might be able to observe it occurring before the cause. This happens any time that the outside observer is closer to the effect than to the cause. However, at no point does that observer observe the effect before the cause occurs. If that observer is, for example, five light years away from the effect and ten light years away from the cause, then the observer still observes the effect five years after the cause occurred.

I'm not a physicist either, but let me see if I can explain this.

Suppose you have three points arranged along a line, say A, B and C, so that A is e.g. 10 light years away from C and B is half way between them, and at the starting time they're all stationary with respect to one another.

Now suppose Alice at point A sets off at the speed of light for point C. An observer at point C will observe that A leaves and arrives at the same time (or almost the same time, if Alice is traveling slightly slower than the speed of light), because the light conveying to point C that Alice has left point A arrives at point C at the same time as Alice arrives at point C. So from the frame of reference of point C, Alice will be at point A until she is at point C. Moreover, at point B, Alice similarly appears to arrive instantly at point B as soon as she is seen to depart from point A, but once she passes point B, point B perceives her to take several more years to reach point C.

Now suppose all three points have instantaneous FTL communications. Now when Bob at point B observes Alice to have passed point B, he call ups Carol at point C and tells her that Alice is headed her way. Well, in the frame of reference of Carol at point C, Alice is still at point A, because it will be several years before Alice sets off from point A and instantaneously arrives at point C. So Carol calls up Alice -- while Alice is still at point A -- and convinces her not to come. Which is obviously a causality violation, because if Alice remains at point A then Bob can't observe her passing point B (and so Bob can't tell Carol and Carol won't know to tell Alice not to come).

Re:Physics

[arose]

Where does gravity fit into this pattern?

Re:Physics

[FrangoAssado]

Isn't it easier to assume that they're not separate entities and that we just don't know how the universe is put together [...]

Sure, you can do that. But if you stop there, you'll know nothing; so we have to go on and keep trying to understand.

[...] than to assume that we understand the universe and there's a 'magical' force communicating across infinite distance?

The thing is, that's not what physicists are saying -- that's just a bastardized explanation used when you can't make someone take a few classes that require quite a bit of math to understand[1]. In fact, most physicists, if pressed, will admit no one knows what is really going on. For example, there's a famous quote by Richard Feynman: "I think I can safely say that nobody understands quantum mechanics".

What physicists do know is a theory that allows us to very successfully predict the outcome of many experiments and understand many phenomena better than any classical (completely understood) theory; and certainly better than if we just give up and assume that "we just don't know how the universe is put together", as you suggest. The amazing thing is that this theory can explain every phenomena we have ever seen (except gravity) and predict the outcome of any experiment we can perform.

The problem is, this theory (quantum mechanics) just doesn't make clear what's really going on. There are many tentative interpretations that are consistent with the theory and the experimental results, each of them having at least one very strange feature (instant collapse of the wavefunction -- which I guess would be the "magical force" you mentioned --, or parallel universes, etc.) that fails to convince most people, including physicists.

Most (all?) physicists working with quantum physics know this very well. But since "what's really going on" is not very important to do research, they don't think about it that much. What they really want is to predict more stuff and come up with new ways to use the strange behavior we see for our advantage.

[1] By the way: there's an excellent very basic course on YouTube about quantum entanglement: http://www.youtube.com/view_play_list?p=A27CEA1B8B27EB67. It only requires high-school algebra (including complex numbers, I don't know it everyone takes that in high school), and patience to follow it through. I guarantee you that you'll end up having a good idea of how this quantum stuff works (at a very basic level) without any mention of magical forces communicating across infinite distances.

Re:Physics

[TheTurtlesMoves]

Quantum entanglement can be thought of as working like that, except that as soon as one of the split particles interacts with anything else at all in any way and the resulting change is "transferred" to the paired particle, that entanglement is broken.

This is not correct. You can *measure* some property and then you know the value of the other particle and entanglement is broken. You can't force the result of the measurement. In other words the only "spooky" action at a distance is the "instant" entanglement braking. And the guy with the other particle can't even observe that either. He/She still needed to make the measurement to determine the state of his/her particle.

This is a quote from user holmstar that explains is very well. (msg id #27448983 but can't work out how to get a link from that)

Entangled particles are like dice that are already rolling, and they stop rolling the moment that either particle is observed.

So you and Joe each have a dice that, say, always roll the same number as each other. You look at your dice to cause it to stop rolling, and see that it rolled a 6. Joe can look at his dice too, and will also see a 6, but he doesn't know if he was the one that caused the dice to stop, or whether it was you who stopped it.

You both see a 6, but no actual information was transferred.

Re:Physics

[TheTurtlesMoves]

There is a quote the goes something like "95% of the news is accurate, the other 5% is about stuff I know".

Re:Physics

[Permutation Citizen]

Personally I think spooky action at a distance isn't spooky at all. Consider the time-honored classic of two electrons in a correlated state being shot out of some device. Assume they are entangled in such a way that when you measure one to be up, you instantly know the other is down. Physicists will say, how could the other electron possibly know this, instantly. But a very simple explanation is that the device always shoots 1 up, 1 down. Sure you don't know if it's up or down until you measure it, but that doesn't make it spooky at all.

Except that other experiments show it doesn't work that way. It's not "you don't know if it's up or down until you measure it", it's you know it's in a superposition state of up and down that "decide" to be only up or only down only when you (or a detector) look at it.

Re:Physics

[rts008]

But I don't think it is very exciting to the general public...

Ah, but your /. crowd is not in that category. Maybe all of us /.'ers are not very interested in this subject: that does not mean a substantial percentage of us are not.

My original intent was to post a snarky/sarcastic comment with the title of "Beam me up, Scotty", followed with a comment about Teleporter/Transporter tech finally advancing a small step in the 'right/correct' direction to make it happen.

Don't give up on us 'laymen', and arm-chair physicists. Maybe we can't join the ranks with our PHD's, but we still want TO KNOW.

Keep posting with 'informed' stuff, some of us love it.
We may stop there, or use that data as a 'spring-board' to further knowledge.

I see it as a 'Win-Win' scenario. YMMV....

Re:Physics

[Americium]

it's in a superposition state of up and down that "decide" to be only up or only down only when you (or a detector) look at it.

I think this is the other most common misconception. The density matrix used to calculate probabilities is a superposition of two states. It says nothing, NOTHING, about the actual particle before measurement. It's only a mathematical description that allows us to calculate probabilities of a measurement.

You are correct in what I said, "you don't know if it's up or down until you measure it" may imply a hidden variable, and is incorrect. However, any interpretation of the electron before a measurement is not described by QM. Furthermore, since hidden variables have been proven to not exist, there is no further insight into the details of the particle that we can gain from using quantum field theory.

Re:Physics

[DarenN]

You're assuming an absolute universal frame of reference. What the GP is saying is that there is no such thing, everything is relative to an observer. (This really reminds me of Leibniz's monads, actually). That means that there is no universal base value for "time".

So the relative effects are all that matter - the fact that things occur "in order" in any arbitrary scale (i.e. time) to any arbitrary observer (i.e. from Earth) is irrelevant. In this case, if you travel in a super luminal fashion from A -> B you (the cause) arrive at B before the effect (light) does. Because there is no universal frame of reference, if you now travel from B -> A you arrive before you left (because you're leaving B before you left A, relatively).

It's tricky enough concept for our monkey brains.

Re:Physics

[Permutation Citizen]

Am I right if I understand what you think by: "Quantum field theory way to describe a particle by a superposition of two states is too weird to correspond to a physical reality." ?

I agree it is weird. I agree also that goals of a theory in physic is not to describe reality itself.

But, actual experiments demonstrate that it's not only current quantum physic theory that is weird. Any theory that would explain outcome of these experiments will have to include some sort of weirdness. Those experiment proves that naive materialism (Physical reality is based on matter) is wrong. I know that from Bernard d'Espagnat's book "On physics and philosophy.".

Re:Physics

[hairyfeet]

Used to be but from what I understand once you get to quantum the universe goes "LOL Goatse' to all our steenkin rules.

On the one hand I'm all for learning about the way things work, especially if they'll have practical applications down the line, but on the other hand this stuff does scare me a little. I'm just waiting for someone to trip over how to make a quantum bomb or to find out cold fusion can be done with the average crap found in a kitchen if done in the right order, thus making it so every nutball with a cause can have a cold fusion nuke.

It always seems like we end up using science to first find really nasty ways to mess each other up and THEN figure out the non military applications for it. Look at rail gun tech, Gerald Bull wanted to use it to make cargo into space as cheap as UPS, instead it will end up making battleships that can throw bus size shells at brown people. Sigh. While I always liked the idea of us advancing to star trek style utopia one day sadly it seems we can't really be happy as a species unless we are ripping each other off or fucking each other up.

Re:Physics

[Alioth]

I still don't see the problem. At point C, they have only *observed* that Alice has not left yet when actually, she has. So while point C might observe that Alice has not left, when they use their FTL phone to call her, they find the call goes unanswered because she's actually heading beyond point B, it's just at point C you merely can't see that yet. That they haven't observed her leaving doesn't mean she hasn't actually left already.

Re:Physics

[Anonymous Coward]

The amazing thing is that this theory can explain every phenomena we have ever seen (except gravity) and predict the outcome of any experiment we can perform.

Leaving aside the fact that it doesn't 'explain' anything only model it, it simply operates at far too small a scale to model most of the 'phenomena we've ever seen'. Can you 'explain' or even model all the operations of a brain using quantum mechanics? You might like to think that it's theoretically possible and that in principle it could work (or you could just put the utter impractiality of any such an atempt down to gravity?) but realistically it hasn't been done and is way beyond anything anyone could try. There's no basis for announcing that it would or could work.

Re:Physics

[Intrepid imaginaut]

You're assuming an absolute universal frame of reference. What the GP is saying is that there is no such thing

There is though, it's just no use to us since we can't observe it. That doesn't mean it doesn't exist. I also cannot see any reason that FTL should imply time travel, any more than supersonic flight should interfere with.cause and effect.

Re:Physics

[locofungus]

Assume they are entangled in such a way that when you measure one to be up, you instantly know the other is down. Physicists will say, how could the other electron possibly know this, instantly. But a very simple explanation is that the device always shoots 1 up, 1 down.

It's a lot more complicated that that.

There are conjugate pairs of variables. For example your photon can be in state 1 or state 0 if you decide to measure it's numeric state but it can be in state A or state B if you decide to measure it's alphabetic state.

If you measure it's alphabetic state then you destroy all knowledge of any previous numeric state. So you measure 0, then you measure A, now when you go back to measure the numeric state it's 50/50 whether you get state 0 or state 1.

Entanglement means that our two photons give opposite results whether we measure their numeric or their alphabetic state.

So if we decide to measure numeric for both we get 0 for one and 1 for the other. But if we measure alphabetic for both we get A for one and B for the other.

Extending your idea we could think that the photon actually has "hidden variables" so that it does know the result of the measurement before it's made but something called Bell's inequality proves that hidden variables cannot be local.

Tim.

Re:Physics

[Anonymous Coward]

3> The properties being measured are not actually separated by distance. For instance if the universe is a Game of Life3D, ie some type of sparse 3D matrix and locations in space contain "pointers to struct Particle", then from within the game you could see information traveling limited to a rate proportional to the number of interactions per second between cells, but changes to the particle itself would appear instantly everywhere the pointer exists.

For instance take something like "struct Pointer { struct Pointer *last_interacted_with; ... }". If you create two particles that last interacted with each other, these particles can travel to different elements in GoL3D and still maintain pointers to each other. Now say interacting with the particle has side effects on the last one it interacted with... spooky action at a distance. But if there is some way to change this data without breaking the link between the two particles then you also have instant information flow.

If you don't assume that a particle's state is physically contained within the particle's location in 3-dimensions then you also can't assume faster than light is a fundamental limit. "Changing the past" needs not be a difficulty either, since that assume time is not universal. Relativity-like effects can be derived from movement (between cells) and interactions sharing the same resource... ie if movement between cells takes 1 tick and some interaction takes 100 ticks, then the faster something is moving the fewer interactions it can make (ie time 'appears' to be slower for it relative to slower-moving particles).

Re:Physics

[Neil Boekend]

The fur don't enter into it. It's stone dead.

Re:Physics

[Anonymous Coward]

Thank you. I went to the comments looking for a comment like yours to confirm I had not gone mad.

Re:Physics

[mhelander]

Couldn't they synch their watches and agree that Joe looks first ?

Re:Physics

[ByteSlicer]

As you said, hidden variables have been proven to not exist (Bell's Inequality).

But what you proposed earlier (that the particles have a defined state from the start, we just don't know what it is until we measure it) implies just that: a hidden variable.

If one calculates the probabilities for an experiment with these unknown state particles, and superimposed ones, then one gets two different results. Experimental results do not agree with the first, but fit perfectly with the second.

So, even though superposition is weird/spooky, it seems to be an accurate description for reality.

There's some even weirder stuff, like delayed choice experiments that can only be explained with quantum spookyness.

Re:Physics

[crunchygranola]

... Physicists will say, how could the other electron possibly know this, instantly. But a very simple explanation is that the device always shoots 1 up, 1 down. Sure you don't know if it's up or down until you measure it, but that doesn't make it spooky at all.

...

But that very simple explanation is provably incorrect. Your intuition is what is called "local realism" - that the two particles actually always have definite (though unknown) states that do not change (realism), and that the two particles are not affected by things happening at a distance (locality). John Stewart Bell developed a theorem about the statistical correlations between entangled particles, and showed that a particular property called Bell's Inequality can distinguish between the local realist interpretation and the quantum mechanical one. In other words, he showed how the two ideas predict different things. Experiments done to test this inequality consistently support the quantum interpretation.

Re:Physics

[locofungus]

The maximum speed of information cannot be exceeded - by definition.

So now we're left asking what the maximum speed of information is. There are only two possible answers, finite, or infinite.

If the speed of information is infinite then there must be a definition of absolute time. I set up a clock and then transmit the time to everywhere in the universe instantaneously. Everyone uses this "UTC" to assign times to events and an absolute ordering of everything is defined and everyone, everywhere agrees on what the time is.

Now it is experimentally observed that time stops (actually it's asymptotic - time slowing is observed) when a clock moves at the speed of light. (subatomic particle decay rates are the classic demonstration of time slowing)

I now have have a second clock identical to the first one. They start together in space and are synchronized at t=0. (Because they start at the same point there's no problem about making sure they have the same time regardless of whether the speed of information is finite or infinite). I send one of them off across the galaxy at the speed of light. After 100000 years my second clock arrives at point B displaying time t=0.

What is the time at B? One of my clocks says t=0, the other (whose time is transmitted infinitely fast to B) says t=100000 years. Both clocks are identical.

The only thing that makes sense is to assume that the maximum speed of information is the same as the speed of light.

Tim.

Re:Physics

[Hope Thelps]

In this case, if you travel in a super luminal fashion from A -> B you (the cause) arrive at B before the effect (light) does. Because there is no universal frame of reference, if you now travel from B -> A you arrive before you left (because you're leaving B before you left A, relatively).

It's tricky enough concept for our monkey brains.

It might be tricky but you haven't explained it at all.

Say point A is 10 light years away from point B and that the two points are stationary relative to one another. Say that you travel at twice the speed of light from A to B and straight then back again. It seems obvious that you'll get back 10 years after you left. Now I realise that just because something seems obvious doesn't mean that it's true. But you haven't explained why you feel that you'd get back before you left instead of years later.

Re:Physics

[Anonymous Coward]

Not to nitpick too severely, but it appears there have been more "the title is unrelated to both the summary and the article" types of postings recently. Furthermore, the wording is often awfully specific or with a more erroneous choice of words, such as 'instant' instead of 'fast', or 'solved' instead of 'mapped'. Please see $RANDOMLUSER (804576) 's comment below for some corroboration regarding the idea.

Re:Physics

[radtea]

But a very simple explanation is that the device always shoots 1 up, 1 down. Sure you don't know if it's up or down until you measure it, but that doesn't make it spooky at all.

The experimental violation of Bell's Inequalities is inconsistent with this "very simple explanation". That is the whole point of such experiments: they prove that the system is in a (locally) indeterminate state. Anyone who argues otherwise is ignoring the facts of reality, and conclusions rigorously inferred from them.

Re:Physics

[Hope Thelps]

Thanks for giving an answer that doesn't revolve around "well we use light to see with so it would look like...".

Re:Physics

[radtea]

As odd as it sounds, there's not actually any difference between teleporting "only" the quantum state of the photons and teleporting the photons themselves -- provide the state you're teleporting is the entire state of the photon.

This is an oft-repeated falsehood, promulagated by the vast hordes of ignorant people who swarm around quantum weirdness like moths on a flame.

If you could "teleport" a photon the photon number at the reciever changes. This is a profound ontological, existential difference from the case where the photon state is "teleported." As it is possible to "teleport" the state of massive particles, perhaps thinking about it in those terms will clear up the mistake for you: if I could "teleport" an electron to the Moon, the electron quantum number, charge, mass and spin of the Moon would be completely different from the case when I "teleport" the state of an electron. Since the two cases are trivially physically distinguishable it is simply false to claim they are the same.

I really don't know why so many people keep repeating this falsehood.

Re:Physics

[TapeCutter]

I also cannot see any reason that FTL should imply time travel, any more than supersonic flight should interfere with.cause and effect.

Supersonic flight is nowhere near relativistic speeds so your Newtonian world won't noticably change. However according to Eienstien when you aproach the speed of light your mass appraches infinity, your length aproaches zero, and time flows like molasses in the winter. This implies that anything with mass cannot travel at the speed of light since it's mass would be infinite and therefore require infinite energy to get to that speed. A photon has no mass but it's direction can be "bent" if it passes near a large mass such as the sun, this implies that spacetime itself is warped by gravity and the photon is actualy traveling in a straght line in it's own frame of reference;ie the direction of travel is both curved and straight depending on the frame of reference. Time acts in similarly bizzare ways depending on the reference frame, ie: the photon "sees" all of eternity flash past in an instant whereas the observer sees it travel through space for billions of years.

The reason time goes bacwards in hypothetical FTL travel is purely mathematical, ie: the sign of T becomes negative (even more bizzare, length also becomes negative). Truth is nobody knows what happens in reality when you travel FTL beacuse in reality FTL travel appears to be impossible.

Re:Physics

[Anonymous Coward]

No, there isn't. People need to stop with the misconceptions about relativity. No object within space can be accelerated beyond the speed of light. There is a lot of wiggle room in there, and there are a lot of examples of events that are faster than light (the inflation period of the Big Bang, for one).

Re:Physics

[TapeCutter]

All of the random ass-headed cruelty of the world will suddenly make perfect sense once you go inside the Monkeysphere

Re:Physics

[rgbatduke]

No, the cat isn't dead. It is in the state |\psi_c> = 1/\sqrt{2} e^i\phi/2 |live> + 1/\sqrt{2} e^-i/phi/2|dead> (where for the sake of simplicity we will assume that = 0, = = 1, that is, the cat has no probability of "dying" if the cat is completely isolated instead of being coupled to an infernal quantum device). I have no idea what phase we should assign to the cat, of course. Is it polarized in the direction of real mortality, or is its polarization strictly imaginary? I'm inclined towards imaginary.

Assuming, of course, that your box is completely isolated from the physical Universe inside an adiabatic box with walls at T = 0. In the event that you don't possess such a box, I assure you, the damn cat is alive or it is dead, not ever in between, whether or not you look inside the box. If it isn't adiabatically isolated, the entire Universe is always "looking inside the box" with its entropy-laden fields.

Perhaps this is how Tesla's "death ray" worked. He constructed a linear phased array of boxes filled with live cats, which were thus in a state of inversion relative to the "ground state of cats" (dead). By triggering the death of the cat in the first box (perhaps with his Tesla coil?) and trapping the resultant death field, he was able to stimulate radiation and produce an intense burst of coherent death from the simultaneous death of all of the cats. Indeed, the device might have been properly named a DASER-Cat (Death Amplification by Stimulated Emission of death-Radiation of Cats), but Tesla was soft-hearted and liked cats, so after using it one time and destroying the Russian Taiga at Tunguska in a way that looked strangely like an air-burst of the nuclear plant aboard an alien spaceship he dismantled it and destroyed the plans (and freed all of the cats he had collected to use for future shots). Schrodinger merely rediscovered it, but was careful to avoid expressing the correct cat wavefunction lest the possibility of coherent death be rediscovered and used for Evil.

rgb

Re:Physics

[bill_mcgonigle]

Hrm, maybe like Relativity has its inertial reference frames, at the quantum level every quantum event is the 'center of the universe' and everything else relates to it. So, an entangled pair could remain in place but the relative quantum interpretation from other points would be defined from their perspective.

Ouch, if I think about that too much it hurts my brain.

Re:Physics

[rgbatduke]

Oops, the damn parser doesn't like dirac bra-kets, does it. The missing line is bra dead | live ket = 0, and bra live | live ket = bra dead | dead ket = 1, normalized orthogonal states of quantum being. Curse you html! (and I'm too lazy to look up character codes, sorry...)

Hell, it beats writing a quiz for my kiddie physics students...

rgb

Re:Physics

[Hope Thelps]

I also cannot see any reason that FTL should imply time travel, any more than supersonic flight should interfere with.cause and effect.

Supersonic flight is nowhere near relativistic speeds so your Newtonian world won't noticably change.

I think the problem here is that there are two sets of answers as to why "causality wold be violated".

The first set babble about how an observer at point B would see you arrive before you leave. This seems to be irrelevant and does lead to the thought that the same explanation would mean that if the observer 'sees' via sonar instead of via radio waves then "causality would be violated" by something travelling faster than sound. I think that's the set the previous poster was referring to. Maybe these explanations have some sort of basis behind but they certainly don't sound convincing..

The second set are along the lines you've provided. These seem to be saying that the model we have (which is supported extensively by experimentation and real world application) basically stops working in any way we understand when you reach the speed of light, probably because you just can't get anything faster than that. But they don't appear to say that causality gets violated; for all the weirdness of "negative time" coming out of the equations I don't think you're saying that there is any identifiable effect that would occur before its cause - at the very most that would be only one explanation of the weirdness. They also don't seem to address why this should make it impossible for information to travel faster if there were some mechanism other than moving matter around - I'm not suggesting that quantum entanglement does allow transmission of information faster than light (or at all) but I'm not sure that your equations would necessarily be relevant if it did.

Re:Physics

[Anthony Mouse]

Yeah, I don't really get it either. As I understand it the problem is that the math says the ultimate speed limit is the speed of light, so the only way for something to be faster than light is for the amount of time it takes to get there to be negative. So then you have the communication getting their before it left, basically -- Alice gets the message five years ago instead of today, or something like that.

Re:Physics

[The End Of Days]

I'm more spooked by the pedant's need to point it out every single time. Where do all you English freaks come from, and why do you think we care?

Re:Physics

[painandgreed]

The problem is that for FTL travel or communication to occur, they must be connected in some way. You can't get from here to there without a path between the two. They are assuming that such a path that the FTL takes will violate causality since they have define the FTL travel to happen instantaneously between two points at the time that it seems instantaneous to the observer. It might, but it doesn't have to as there can be FTL travel that does not seem instantaneous to the observer.

Wormholes were suggested for such FTL travel because they get around that. Your path AC through the worm hole may take much less time than your path ABC through normal space. You can also perform a similar thought experiment with our ABC around a black hole near the event horizon. Both trips between ABC and AC are observed to take place in a straight line at the speed of light, but AC is shorter, thus it appears that AC is travelling FTL from the observations of B. The same thing happens with gravatational lensing. Light passes both sides of a star from the same point and reaches the same endpoint at different times. Although both are happening at the speed of light in a straight line, one can be shorter than the other.

The problem is two fold. One, we are suggesting FTL travel without defining how such FTL is supposed to work. While there are some that cause causality violations (and I don't think anybody has really shown that science disallows causality violations yet), not all have to. Wormholes, hyperspace, etc all allow for casual FTL, as FTL is being determined by the observations in flat space-time.

Re:Physics

[Draque]

I think it has to do with transmission of q-bits within memory. It's not for communication between two different people, but communication of a q-bit from one memory location to another, which *would* be a big step forward... but not a step that was communicated well within the article. ^^()

Re:Physics

[FrangoAssado]

Sure, you can point at things like brains and say "that's too complex, we don't understand it". But right now we have no reason to believe we need new physics to explain it, and we have a pretty good reason to believe we don't: at the most basic level (which we do understand reasonably well), the brain works with electrochemical reactions, and we have a pretty good understanding the fundamentals of that. [Although it's possible that quantum effects are important, as we have found that it's the case with photosynthesis (http://www.youtube.com/watch?v=wcXSpXyZVuY).]

But, as far as we know, it's likely that understanding brains will need something other than a breakthrough in our understanding of the fundamental working of the universe at a very low level (which is what quantum mechanics is). There's so much we don't understand of biology that will probably ultimately need no new physics to understand. Of course, it's not a settled matter -- science never is, and there's always a chance that understanding something will need a radically different way of thinking.

But that's beside the point I was trying to make, which is this: our current understanding of the universe, using quantum mechanics, is a hell of a lot better than shrugging and saying "we just don't know how the universe is put together", although it's easy to be tempted to believe so if all you know about quantum mechanics is that it's about "magical forces communicating through infinite distances".

Re:Physics

[Omnifarious]

You are wrong. This interpretation has been disproven. There are some subtle statistical tests that disprove any 'hidden state' theory, including this one. Research the Bell Inequality and you will learn what they are and the experiments that have been run.

Re:Physics

[Omnifarious]

That's my feeling on the matter. They are not separate entities.

I'm wondering though, how that aligns with the frame of reference idea from relativity. Is there only one frame of reference for 'both' particles? What does it mean to have a single frame of reference that occupies two distinct locations in space?

If they have separate frames of reference, then they are not the same particle and there must be some other explanation. But if that's true, then how can state collapse be instantaneous? If they each have a distinct frame of reference, that means there is no notion of simultaneous that has any meaning. When does the state collapse in each frame?

Either interpretation poses grave problems for relativity, quantum mechanics, or both.

Re:Physics

[blueg3]

You're just equivocating on the definition of "teleport". Quantum teleportation means and always has meant exchanging the states of two otherwise-identical particles. What I was saying is that this is the same as exchanging the particles themselves. This is not the same as the definition of "teleport" that involves motion of mass from one point to another without going through the intervening space. But then, that definition has never been applied to quantum teleportation, so I don't see why you would choose to use it.

Re:Physics

[bill_mcgonigle]

Does this make any sense to you?

I think we're asking the same question.

Re:Physics

[Americium]

So my analogy was obviously incorrect, but so is any other analogy. QM says nothing about the underlying details of the particle before measurement. The wave function collapses, the particle is just observed.

"it's in a superposition of two states" is like saying the "position is washed out over the entire universe", it's just the mathematical function used to predict probabilities that's in a superposition, and it's just another mathematical function that's washed out over the entire universe.

The underlying math doesn't say anything about the particle, it just lets us calculate probabilities. The position operator is in infinite dimensional Hilbert space, but that doesn't mean every position is a new dimension.

Quantum erasure is kinda spooky, but it doesn't magically change the picture on the wall when you erase the information, which is implied in almost every article on it.

Re:Physics

[Americium]

Incorrect, it's only correlated on 1 axis, (numeric or alphabetic), and if you measure on the incorrect axis there is no correlation and the correlation is destroyed. See Quantum Cryptography for a detailed method of dealing with this by using a regular electronic signal to first tell the receiver what axis to measure on.

Re:Physics

[TapeCutter]

Exactly, our model of reality breaks down when contemplating things such as FTL travel and singularities. It seems to say that causality is broken but we simply don't know because with our current state of knowledge nature will not allow us to do the experiments. However experiments on the spontaneous creation of matter-antimatter pairs by "borrowing energy from the future" (ie: the quantum vacum) does seem to indicate causality can be broken at the quantum scale.

Re:Physics

[Anonymous Coward]

I'm more spooked by the pedant's need to point it out every single time. Where do all you English freaks come from, and why do you think we care?

English freaks come from England of course. The reason I assume you care where they come from is beause you went to the trouble of asking.

Re:Physics

[Americium]

So my analogy was obviously incorrect, but so is any other analogy. QM says nothing about the underlying details of the particle before measurement. The wave function collapses, the particle is just observed.

"it's in a superposition of two states" is like saying the "position is washed out over the entire universe", it's just the mathematical function used to predict probabilities that's in a superposition, and it's just another mathematical function that's washed out over the entire universe.

The underlying math doesn't say anything about the particle, it just lets us calculate probabilities. The position operator is in infinite dimensional Hilbert space, but that doesn't mean every position is a new dimension.

Re:Physics

[Anonymous Coward]

This is incorrect. Wormholes, hyperspace, et al, all involve time travel as well. There doesn't need to be a path, all that's necessary is that information leave one place and enter another before its own light cone reaches it.

Re:Physics

[Anonymous Coward]

The first set babble about how an observer at point B would see you arrive before you leave. This seems to be irrelevant and does lead to the thought that the same explanation would mean that if the observer 'sees' via sonar instead of via radio waves then "causality would be violated" by something travelling faster than sound. I think that's the set the previous poster was referring to. Maybe these explanations have some sort of basis behind but they certainly don't sound convincing..

Actually, that's not what I said -- on your first trip, some reference frames would see you arrive at B before your departure at A, but obviously that doesn't include an observer sitting at A. At this point, it "looks like" you've arrived before you left to some people, and others would disagree; the latter disagreement is where SF handwaves away time travel. All well and good. (Well, wrong, actually, but you're not likely to violate causality in a single shot, so whatever.)
  The problem is that if you then immediately go FTL from B back to A, you will arrive before your original departure in ALL reference frames, including your own. You'll be able to shake hands with yourself before yourself goes off on the trip you've come back from. Heck, you might even have a few years to wait for you to leave, depending on how far you've exceeded lightspeed, and the distances travelled.

  This is all highly counterintuitive, because our monkey brains automatically assume that there's some sort of big clock out there ticking away and time runs the same speed everywhere for everybody. But we've already confirmed the existence of relativistic time dilation via experiment! Time slows for observers moving at high speeds, and the higher the speed, the greater the slowdown.
    At light speed, time dilation becomes infinite, and time stops for those on board our hypothetical vessel. Exceed that speed, and dilation increases into negative numbers, and you're moving backwards in time, depending on reference frames.

  See http://www.theculture.org/rich/sharpblue/archives/000089.html for some nifty graphs and such that show exactly what happens to reference frames under relativistic speeds.

Re:Physics

[tonywestonuk]

No, sir, you are mistaken.

>>Not all the photons will get through...

If you use a polarising filter, followed by a detector to detect only half of the photons arriving, then your are right.

However I did not say this. Certain kinds of crystal (calcite for instance) will bend the path of a photon based on its polarisation. So, wire up 2 photon detectors at different exit points from a calcite crystal, and all photons (minus random losses due to the material itself) will get through and be detected, both alignments..

>>>No, this is not the case at all. If you do not know which axis to measure on you destroy the entangled state.
**Completely incorrect**. Quantum theory says that you'll get the entangled photons polarization will correlate to each other .** It doesn't matter** what axis you measure on. If this wasn't the case, well, there wouldn't be anything special about this facet of quantium physics, that couldn't be explained with classical.

>>The spooky effect is that you do see either a quicker or slower dropoff than the cos^2(theta) for polarizers with these entangled state, I can't remember which (quicker/slower).

If you took 2 polarisation detectors, each measuring one of the entangled pair of photons, then cos^2(theta) describes how often the two bitstreams will correlate. However, theta is the angle between the photon detectors... It has no dependence on the original polarisation the the photons are emitted. Indeed it can be shown the emitted photons **cannot actually have** a specific polarisation.

Re:Physics

[TheTurtlesMoves]

And what does that communicate? You still cannot control what the dice will be when you do look.

Re:Physics

[Americium]

**Completely incorrect**. Quantum theory says that you'll get the entangled photons polarization will correlate to each other .** It doesn't matter** what axis you measure on. If this wasn't the case, well, there wouldn't be anything special about this facet of quantium physics, that couldn't be explained with classical.

Read any paper on quantum cryptography and you'll realize you were mistaken. There is indeed something special about this, it's the classical result where it doesn't matter what axis you measure on. This phenomenon is behind the idea of using quantum encryption for serial numbers on money. Then when the counterfeiter tries to read the serial number without knowing what axis to measure on, not only does he get bogus results, but he also destroys the serial number of the dollar bill he's trying to counterfeit.

If you took 2 polarisation detectors, each measuring one of the entangled pair of photons, then cos^2(theta) describes how often the two bitstreams will correlate. However, theta is the angle between the photon detectors... It has no dependence on the original polarisation the the photons are emitted. Indeed it can be shown the emitted photons **cannot actually have** a specific polarisation.

Read any paper that does this exact experiment with the entire purpose of the experiment to show that it's not cos^2(theta) with correlated photons. Cos^2(theta) is the classical result that would occur if there wasn't entanglement.

Re:Physics

[Permutation Citizen]

Your position is perfectly valid. We don't have a direct access to physical reality itself. Current physics theories are successful but known to be incomplete.

At first view, quantum physic theory (because of the observer role) seems incompatible to physical realism. That is the philosophical stance that there is a reality independent from human mind.

What I wanted to point out earlier is that you can't expect a new, better theory, that supplant current quantum physic and where everything can be explained in a way compatible with common sense.

My feeling is that quantum physic is "true" in a sense that it help us to understand the world. So I tend to think that wave function may have a counterpart in reality itself. This means my preference goes to Everett interpretation.

This article of Tegmark and Wheeler is very good on the subject:
http://arxiv.org/PS_cache/quant-ph/pdf/0101/0101077v1.pdf

Re:Physics

[Americium]

Thanks for the article, I'll be sure to read it soon, perhaps after much coffee first.

  I suppose it's a little to soon to hope that anyone on slashdot would happen to know the perspective that string theory gives us, and if it agrees or not with the Everett interpretation, which in my opinion is quite a stretch; although the multiverse theory that certain interpretations of string theory suggest are almost as bizarre. Doesn't the Everett interpretation suggest you could be the Schroedinger cat, and 'you' wouldn't die, your body might in this reality, but each time you live on in another 'world'?

And you're correct, I was making too strong a case that QM could be explained away by common sense, but I still think the weirdness is overestimated in almost every article on the subject.

I can still expect a better theory that is somewhat more compatible with common sense. Perhaps it's simply a string vibrating at two frequencies, and our measurement devices can only detect a single frequency at a time. Which then would imply it is actually in a superposition of two states...- I have no idea if this is what string theory actually suggests.

Re:Physics

[Permutation Citizen]

Doesn't the Everett interpretation suggest you could be the Schroedinger cat, and 'you' wouldn't die, your body might in this reality, but each time you live on in another 'world'?

I can't explain better than Tegmark does in the article I linked.

And you're correct, I was making too strong a case that QM could be explained away by common sense, but I still think the weirdness is overestimated in almost every article on the subject.

Sure. Actually, things are simpler and paradoxes disappear with Everett interpretation.

Re:Physics

[painandgreed]

They can and do in the trivial sense that all travel is time travel as our definition of travel is distance over time, but don't have to in the way we are talking about. Even then we are going to be going by who the observer is, point A, point B, or the person going between the two. Worm holes and the like can travel into the past or the future and anywhere in between including the present.

I would disagree on the path. For something to get from point A to point B there must be a path, a criteria for connection between the two points, otherwise multiple points and maybe all points in the universe would be observed as the same and endpoint of travel would be random.

Near?

[Dan East]

Neither Australia nor Japan is close to me, so unfortunately Instant Quantum Communication Is Not Near.

Re:Near?

[snookums]

And if you are near Australia, the PopSci website force-redirects you to the .au URL where this article is 404, so you can't find out about it.

Re:Near?

[mykro76]

Oh so that's why the URL in the article wasn't working for me. Thanks. Stupid website design...

Re:Near?

[Anonymous Coward]

https://proxify.com/u?http://www.popsci.com/technology/article/2011-04/quantum-teleportation-breakthrough-could-lead-instantanous-computing

Re:Near?

[Anonymous Coward]

Google cache overcomes such idiotic notions of geographic location having any meaning on the internet.
http://webcache.googleusercontent.com/search?q=cache:khT6NqoI1I8J:www.popsci.com/technology/article/2011-04/quantum-teleportation-breakthrough-could-lead-instantanous-computing+http://www.popsci.com/technology/article/2011-04/quantum-teleportation-breakthrough-could-lead-instantanous-computing&cd=1&hl=en&ct=clnk&source=www.google.com

Re:Near?

[Anonymous Coward]

What's this? Slashdot not catering for Australias every need? But I thought we were your favourites! Someone repost the article posthaste!

This is of relevance

[atari2600a]

http://xkcd.com/465/

Ah, so this is the dupe

[countertrolling]

The original article will post six hours from now... but what is 'now'?

Re:Ah, so this is the dupe

[ae1294]

The original article will post six hours from now... but what is 'now'?

Colonel Sandurz: Try here. Stop.
Dark Helmet: What the hell am I looking at? When does this happen in the movie?
Colonel Sandurz: Now. You're looking at now, sir. Everything that happens now, is happening now.
Dark Helmet: What happened to then?
Colonel Sandurz: We passed then.
Dark Helmet: When?
Colonel Sandurz: Just now. We're at now now.
Dark Helmet: Go back to then.
Colonel Sandurz: When?
Dark Helmet: Now.
Colonel Sandurz: Now?
Dark Helmet: Now.
Colonel Sandurz: I can't.
Dark Helmet: Why?
Colonel Sandurz: We missed it.
Dark Helmet: When?
Colonel Sandurz: Just now.
Dark Helmet: When will then be now?
Colonel Sandurz: Soon.
Dark Helmet: How soon?

Okay, but...

[MrEricSir]

Will this instant quantum communication make my AT&T 3G signal any faster?

Re:Okay, but...

[Pharmboy]

No, this won't make any signal faster. Only the transmission of data would be faster.

Re:Okay, but...

[hedwards]

Yes, but only if the other party doesn't attempt to listen.

Yeah, Right

[Greyfox]

Do you think any government on the planet would allow that? I'm sure any researcher who so much as hints that he's actually close to a breakthrough on that topic quietly disappears in the night.

Re:Yeah, Right

[xMrFishx]

So, I herd you like conspiracy theories...

Re:Yeah, Right

[Bruce_Nash]

So, I herd you like conspiracy theories...

How does that compare to herding cats?

Re:Yeah, Right

[Anonymous Coward]

That's just what Fleischmann and Pons want you to believe...

Re:Yeah, Right

[TemperedAlchemist]

What are you talking about? This is a huge leap for the Federation.

Re:Yeah, Right

[fabioalcor]

I'm sure any researcher who so much as hints that he's actually close to a breakthrough on that topic quietly disappears in the night.

Don't worry, he will reappear in another place, "alive" again and unchanged.

Re:Yeah, Right

[Nethemas the Great]

Wow, your comment is either truly profound or you have no clue how to spell. Quick, someone check in on his cat...

Re:Yeah, Right

[Anonymous Coward]

Thats only in the US, in the free world we don't have to live with that sort of fear.

Re:Yeah, Right

[xMrFishx]

Intentional misspelling is intentional. My comment is about as profound as the previous, that governments would just disappear quantum physicists for effectively doing "science". I'm not entirely sure I'd see the point. It would just produce a technological dark-age (relatively to the potential of having mainstream quantum machines/computers eventually). The two posts, you see, are entangled. One is spun into silliness in the form of conspiracy, the other is spun in the opposite direction as a Yo Dawg meme.

Re:Yeah, Right

[Thing 1]

So, I herd you like conspiracy theories...

How does that compare to herding cats?

In one instance, you're making sure that felines are in their appropriate (to you) places. In the other, you're making sure that "you [who] like[s] conspiracy theories" is in the appropriate place. I think most would agree that managing software developers is more akin to the former than the latter (although there is a significant overlap in attraction to conspiracy theories, as there is attraction to software development, generally due to the edge cases).

Re:Yeah, Right

[mug funky]

so i put a tinfoil hat in your tinfoil hat so you can block out the aliens while you block out the aliens.

Re:Yeah, Right

[Anonymous Coward]

Minus one meme recognition.

Re:Yeah, Right

[Anonymous Coward]

He's probably a journalist. Herding conspiracy theories is a major component of their job spec.

Re:Yeah, Right

[517714]

As long as it is instantly and not three days later, we do not need to introduce religion into the issue.

Re:Yeah, Right

[Compaqt]

Did someone say Hurd?

Re:Yeah, Right

[Anonymous Coward]

Except that, quantum "action" space is neither here nor there. It's everywhere. Literally. And everywhen. So, quantum communication, once you know the parameters, can - theoretically - be universally retrievable.

Of course, things realy become fun next week, when they announce quantum-fabbing-at-a-distance.

Meanwhile. Instant communication with the martian robots? (Man, that phrase is so '50s pulp sci-fi it hurts!).

Re:Yeah, Right

[barrtender]

Wouldn't it make more sense for the "I herd you like conspiracy theories" to be parsed as equivalent to "I place you in the appropriate place in the same fashion as conspiracy theories would"?

So, he puts you in a basement with a tinfoil hat. That might even be creepier.

The Upshot:

[TexVex]

It's the same old teleportation thing, except now faster and with higher fidelity.

The article is extremely light on information and (as usual) rife with such misleading phrases as "SchrÃdinger's Cat" and "spooky action at a distance".

Re:The Upshot:

[bill_mcgonigle]

and "spooky action at a distance"

Did you just make that up or do you have a saved response for quantum teleportation articles?

Re:The Upshot:

[Anonymous Coward]

That phrase was actually Einstein's objection to quantum mechanical predictions. Check out the EPR Paradox.

Re:The Upshot:

[Gastrobot]

The phrase "spooky action at a distance" was coined by Einstein for the ability of one particle to instantaneously affect another.

Re:The Upshot:

[daenris]

yes, but the phrase "spooky action at a distance" is not in the article, as TexVex seems to be suggesting, indicating that he's throwing out the criticism without actually having read the article.

Re:The Upshot:

[Thing 1]

and "spooky action at a distance"

Did you just make that up or do you have a saved response for quantum teleportation articles?

The comment was teleported in.

Re:The Upshot:

[MacGyver2210]

"the phrase 'spooky action at a distance' is not in the article"

http://en.wikipedia.org/w/index.php?title=Spooky_action_at_a_distance

That's because "spooky action at a distance" is really called Quantum Entanglement...which IS in the article.

FTFA: "The team employed a mind-boggling set of quantum manipulation techniques to achieve this, including squeezing, photon subtraction, entanglement and homodyne detection. The photo above depicts their device, nicknamed the Teleporter, in the lab of Akira Furusawa at the University of Tokyo."

Re:The Upshot:

[niftydude]

The article is extremely light on information

Of course it is - just because we can do quantum teleportation - doesn't actually mean there is anyone out there who understands how it works...

Re:The Upshot:

[jomama717]

Off topic, you missed a good one: LOST DASH

Re:The Upshot:

[Anonymous Coward]

I think he was pointing out that there's no occurrence of the phrase "spooky action at a distance" in the article, and that the TexVex is making stuff up.
But yea, that article is totally useless, and the original document is behind a paywall.

Re:The Upshot:

[gr8_phk]

The phrase "spooky action at a distance" was coined by Einstein for the ability of one particle to instantaneously affect another.

Einstein used that phrase because he didn't believe in the "spooky action at a distance", but rather thought each particle contained the information since their departure. IMHO, he was right. Just because physicists haven't figured out how that information is carried doesn't mean it isn't there - though the experiments that show there is no information seem convincing.

Re:The Upshot:

[Zeromous]

I think he meant, spooky action a distance was not even mentioned?

Re:The Upshot:

[Anonymous Coward]

I doubt someone with a UID of 4333 doesn't know of the phrase "spooky action at a distance". I think maybe someone jacked your account.

Re:The Upshot:

[Anonymous Coward]

Fucking magnets! How do they work?

That's not how quantum entanglement works

[Anonymous Coward]

Transferring information faster than the speed of light through the use of quantum entanglement is impossible. Only through the use of a second, traditionally light-speed-bound communication channel one make any use of the oddness that is quantum entanglement.

That said, it might still have practical uses, but instantaneous communication to the other side of the galaxy is not one of them.

Re:That's not how quantum entanglement works

[xMrFishx]

Although I figured using it as a network interconnect across the planet, say EU to US would be a good start, of course depending how quick you can flip that bit as to whether it's even feasible vs under sea cables. Though saying that I figure it's far more complex than merely using it as an overcomplicated cable. No doubt thinking of traditional uses for quantum processing systems is too simple, but I'm not a quantum physicist so I'm a bit stuck there. The engineer part of me says "Right, now what? Let's find a use for it and start building another one."

Re:That's not how quantum entanglement works

[Anonymous Coward]

Its *impossible* to use entanglement to perform communication instantaneously over *any* distance. No-Signal Theorem and No-Clone Theorem both play a roll here. Its not a matter of "well we just haven't figured it out yet", its a matter of "oh we can't violate the basic laws of physics" (see causality).

Re:That's not how quantum entanglement works

[Anonymous Coward]

A scientific theory is not infallible. Although, from what we've observed, it may be highly unlikely that anything could violate it, it is not necessarily impossible. It takes but a single example to disprove it, no matter how unlikely that is.

Re:That's not how quantum entanglement works

[Anonymous Coward]

The source linked from the article clarifies that light-speed classical communication is needed. The accomplishment is that they are able to do a much better job of handling errors. I assume this also requires setting up the entanglement ahead of time, although that was not clear.

Re:That's not how quantum entanglement works

[glwtta]

A scientific theory is not infallible. Although, from what we've observed, it may be highly unlikely that anything could violate it, it is not necessarily impossible. It takes but a single example to disprove it, no matter how unlikely that is.

That's technically true, I suppose, but it doesn't seem like a productive way to do research - essentially your only chance of success is if everything we know about physics is wrong.

Re:That's not how quantum entanglement works

[Anonymous Coward]

Oh, I know. I was just clarifying that because it sounded like he was saying that nothing can violate a scientific theory.

Re:That's not how quantum entanglement works

[Anonymous Coward]

WTF are you smoking?

Although I figured using it as a network interconnect across the planet, say EU to US would be a good start, of course depending how quick you can flip that bit as to whether it's even feasible vs under sea cables.

Did you not just read the post you replied to that explains you cannot do that? Literally, for every qubit you transmit instantaneously, you must transmit one bit some other, normal, slow way (i.e. the undersea cable, or maybe a satellite link) to make any use of it. Therefore your initial idea of using it for a network interconnect is already discredited, so why in HELL do you think we all want to read it anyway?

(Also, "although" is a word, it has a meaning, it's not just there for you to drop in your sentences at random. Although you figured $SOME_BULLSHIT, WHAT? )

Though saying that I figure it's far more complex than merely using it as an overcomplicated cable. No doubt thinking of traditional uses for quantum processing systems is too simple, but I'm not a quantum physicist so I'm a bit stuck there.

Oh, now you tell us that you think it's complicated, and you think it's "too simple" for someone else to understand, but you don't understand it at all (in case we couldn't get that from your bogus first reaction). So informative.

The engineer part of me says "Right, now what? Let's find a use for it and start building another one."

Ah, the only part of your message that doesn't actively make everyone who reads it stupider -- just a statement of support and enthusiasm. Do you perchance use AOL?

Anyway, next time, try to be a little more concise. You'd have conveyed the same information, and wasted much less bandwidth and time, if you'd just summarized it, like this:

xMrFishx is stupid.
xMrFishx is not a quantum physicist and does not understand quantum teleportation.
Go, team, go!

-- Summer Glau

Re:That's not how quantum entanglement works

[Omestes]

- essentially your only chance of success is if everything we know about physics is wrong.

It wouldn't be the first time.

That said, I truly doubt that most of the fundamentals are wrong at this point, but they may be. I wouldn't be terribly shocked if something we held as a law was completely demolished in my lifetime, I would be shocked if this didn't happen actually.

Re:That's not how quantum entanglement works

[Anonymous Coward]

Windmills do not work that way!!

Goodnight!!

Re:That's not how quantum entanglement works

[Anonymous Coward]

You do not need to carry any information along, just record that the transfer happened or not, that is 1 or 0.

Re:That's not how quantum entanglement works

[Nyder]

Transferring information faster than the speed of light through the use of quantum entanglement is impossible. Only through the use of a second, traditionally light-speed-bound communication channel one make any use of the oddness that is quantum entanglement.

That said, it might still have practical uses, but instantaneous communication to the other side of the galaxy is not one of them.

Of course not, we don't have anything on the other side of the galaxy yet.

Re:That's not how quantum entanglement works

[TheDarkMaster]

I would not be so sure that communication faster than light is "impossible". Remember that the speed limit applies to things that may have mass and/or are moving from point A to point B. If you get a communication system that does not involve moving something with or without mass from one point to another, then how you would apply a speed limit on something that does not move?

Re:That's not how quantum entanglement works

[Anonymous Coward]

Yet. If something is sent to the other side of the galaxy, when it arrives thousands of years later, instant communication might be possible.

Re:That's not how quantum entanglement works

[Synn]

In my limited understanding the speed limit is a constant in the universe, sort of a "nothing goes faster than this" and light(along with other things) just travels at this speed.

And light itself isn't special. You can slow down light in certain mediums and have other particles go faster than light in those mediums. So you CAN go faster than light. But you still don't exceed that universal constant speed limit.

Re:That's not how quantum entanglement works

[gr8_phk]

You do not need to carry any information along, just record that the transfer happened or not, that is 1 or 0.

That was my first thought - someone at one end of an entangled particle stream does either does measurements (collapses the wave function) or does not. The person at the other end then checks their particle stream for collapsed-ness and uses that as data. This gets to the real crux of the problem - physicists have to way to tell the difference between particles whose wave function has collapsed and those that have not, so this can't be used to transmit information. Not only can they not tell the difference between collapsed and un-collapsed, they can't tell you what it means. Understanding definitively stops right there.

Re:That's not how quantum entanglement works

[Neil Boekend]

Until you observe the theory it has been proved and disproved at the same time.

Re:That's not how quantum entanglement works

[Anonymous Coward]

So Spooky Action at a distance isnt so Spooky and it adheres to the speed of light at the quantum level ?

Re:That's not how quantum entanglement works

[Anonymous Coward]

The channel would, obviously, have to interface with traditional networks on both end. How are you able to determine that dealing with quantum entanglement the transmission speed is a function of distance? Admittedly, the summary is short on details and I don't have access to the full text of the article.

Re:That's not how quantum entanglement works

[Anonymous Coward]

I swear, every time someone does a quantum teleportation experiment, some reporter gets the wrong idea and claims that the transfer of information was instantaneous. Every damn time, without fail.

It's only instant if our best tested theories of both quantum mechanics and relativity are wildly wrong.

Re:That's not how quantum entanglement works

[Anonymous Coward]

Bugger, and here I was thinking they finally have a solution to Battlefield 3 lagging ...

Re:That's not how quantum entanglement works

[Anonymous Coward]

That said, it might still have practical uses, but instantaneous communication to the other side of the galaxy is not one of them.

Well, not totally true, as we know the law of speed of light is local, so one is fine creating a worm hole between two places in the galaxy. Locally you or your photons are still traveling below or at the speed of light, but for an outsider watching you just disapear in one place and suddenly pop up in another place in the universe/galaxy.

Re:Destroyed?

[Anonymous Coward]

Totally not cool man, just totally not cool at all.

Think like a Dinosaur

[PhreakOfTime]

There is no law, there is just an equation. It must always be balanced.

The Equation must be balanced

Re:Think like a Dinosaur

[Thing 1]

There is no law, there is just an equation. It must always be balanced.

The Equation must be balanced

Thanks for that! In reading your comment, before I saw the link, I was already picturing that goofy bald-headed actor from Just Shoot Me, as I'd seen that Outer Limits episode many years back. Really disturbing... (The moral dilemma, that is, not the goofiness or hair loss.)

Not really.

[Anonymous Coward]

Law? Last I checked, c is still a theory, along with most of the stuff we know that are wrongfully labelled "laws".
In fact, nothing rules out Tachyons either. The only thing that rules out FTL is Relativity, which we know isn't even near correct, just correct enough for the uses we care about now. (just like Newtons laws have their own uses as well)
People always cite collider experiments as proof, but as any good scientist should know, correlation does not mean causation.
Just because light travels at the that speed, doesn't mean there aren't things that can't go faster.
In fact, the speed of light in a vacuum isn't even the fastest speed, the speed of light in between 2 charged plates small enough to prevent virtual particle pairs from interrupting the beam of light is faster. (not sure how much again, don't think it was that much faster though*)
Most of the time, light is just bouncing from particle to particle, very rarely does it experience times where it is in a true empty space.

For all we know, the thing keeping galaxies in the states they are in could be down to particles with some sort of FTL influence, rather than WIMPS or whatever else there is.

Not meaning to beat in to science or anything, but we don't know shit.
And I hope these kinds of experiments continue to grow.
The quantum world is a messy place.
The speed of light could be ripped apart next week for all we know.
Some dude could come back from the future to tell us to watch out for the alien dinosaurs from the planet Zorg.
While it is unlikely, it could very well still happen.

* links here
PDF - The Light Velocity Casimir Effect
View the PDF in Google Docs

Re:Not really.

[DarenN]

Law? Last I checked, c is still a theory, along with most of the stuff we know that are wrongfully labelled "laws".

Nope, c, the speed of light in a vacuum is measurable, so it's accurate to the limit of our technical ability to measure it.

People always cite collider experiments as proof, but as any good scientist should know, correlation does not mean causation.

This tired and weary bit of "wisdom" ignores the fact that causation implies correlation, so correlation is a good place to start.

Sure it is.

[Anonymous Coward]

Instant Quantum Communication Is Near*

* Note that Instant Quantum Communication requires our advanced Friends and Quantums plan, at $159.99/month. Instant Quantum Communication may not be Instant, depending on Quantum traffic patterns in your service area. Instant Quantum Traffic may be routed to a lower priority because we want you to buy our Quantums, not Netflix's Quantums.

Article says nothing

[Anonymous Coward]

I RTFA, but I'm unconvinced as to what they actually achieved. The article says researches in Australia and Japan teleported light without damage to the information and without taking forever to copy that one state (so they upgraded their quantum modem so to speak).

But... TFA lets me assume they teleported that FROM Australia TO Japan or the other way around, and somehow I feel they didn't. I feel more like they teleported that photon independently within their separate laboratories. Why? Because quantum entanglement isn't that big of a deal: you split one thing into two, and one's state depends on the state of the other, like two gears that used to spin together and you separated them and by measuring one's state you automatically know the state of the other. Unless of course I misunderstood Wikipedia. :)

How long....

[asm2750]

.... until we have head crabs jumping around latching on to people when this technology goes wrong?

no we are useing that for MLB EI HD

[Joe The Dragon]

no we are useing that for MLB EI HD

Re:no we are useing that for MLB EI HD

[gcnaddict]

That explains everything.

I was wondering why the Boston Yankees were winning by 4 runs. This never happens.

good god

[Anonymous Coward]

If I were a grandfather, I'd buy a gun today.

Re:fix

[Anonymous Coward]

I wasn't posting from a quantum computer until you looked at this.

The Federal Reserve Already Uses This

[Anonymous Coward]

1. Don't observe the price of commodities when calculating inflation.

2. Observe the price of everything else.

3. Massive ammounts of money are magicly transported from everything else into commodities.

4. So much money flees the measurement that it actually looke like there's deflation.

5. In fact, you faulty observations have caused you to trick yourself into seeing something that isn't there.

6. ???

7. Profit. For somebody. I'm sure.

Re:fix

[ae1294]

I wasn't posting from a quantum computer until you looked at this.

That's why I invested in a box of kittens. You feed them into the Quantum computer to avoid problems like that.

Re:fix

[mcneely.mike]

that's okay... you're both alive and dead.

Wonderful world of quantum computing

[formfeed]

This email is to inform you that your cat is either alive or dead.

Re:Wonderful world of quantum computing

[Bengie]

Every time I put a cat in a box and come back to it, I measure the cat as dead. Starting to think it's not truly random or I'm getting bad luck.

Re:Wonderful world of quantum computing

[Solensean]

Your RNG is broken!

Yawn...

[Holi]

Wake me when they have an ansible.

When they can do this with an entire human

[Anonymous Coward]

who would volunteer?

wow

[koan]

What's the distance between transfer points, was it between Japan and Australia or were those just 2 lab locations running separate experiments? information transfer faster than light?

Re:wow

[JSBiff]

My understanding is that even quantum entanglement is still limited by the speed of light. I think the main advantage of quantum entanglement vs. radio communication is greater privacy. Also, I'm not completley positive on this, but I think that, whereas a limited number of users can 'share' a bit of the RF spectrum, as long as you have more entangled particle pairs, you have essentially unlimited bandwidth.

Teleportation is commonplace now?

[kvvbassboy]

...previous teleportation experiments...

There are practical experiments being conducted in teleportation and they were not posted on Slashdot? I thought it was all just theoretical blah blah... We seriously need more articles like this.

Re:Teleportation is commonplace now?

[Xeranar]

Honestly I haven't been following quantum science since I gave up engineering for history in college. That was several years ago and last I checked they did manage to "transport" light but it degraded because it was split. Essentially they've perfected the basic ability. Now it's time to move on towards real-world solutions. If this isn't the start of instant communication across the world at the very least think of the speed data centers could reach. If the initial progress was done just in room to room movements the speed at which processing could occur for computers and massive data centers is enormous.

Wahey

[Maritz]

Hopefully now we'll soon be able to instantly transmit a stream of random bits wherever we choose!!

Re:fix

[akh]

3 kittens were harmed in making this post?

Where was this experiment conducted??

[kvvbassboy]

The TFA says "researchers from Australia and Japan", and mentions a research institute. But doesn't say which lab this experiment was performed in?

Re:Destroyed?

[Anonymous Coward]

it was a little bit cool. chill.

My computer cords are always getting entangled.

[Anonymous Coward]

My computer cords are always getting entangled.

Kirks lamant

[SnarfQuest]

This is a major advance, as previous teleportation experiments were either very slow or caused some information to be lost>/quote>

Spock, I seem to have lost some information that was very important to me. What am I going to do with all those alien chicks now?

Poor article

[glwtta]

In a real-life use of Schrodinger's theoretical paradoxical cat ...

This phenomenon is described in Erwin Schrodinger's quantum mechanics thought experiment, in which a cat is simultaneously dead and alive, depending on the state of a subatomic particle.

I'm sure Dr Schrodinger would be glad to know that his thought experiment, showing the shortcomings of a naive interpretation of CI, is now taken as a literal description of quantum mechanics.

He did take it for granted - and I really think this is quite intuitive - that cats can't be both dead and alive at the same - why is this so hard for people (and especially popular science writers)?

Re:Poor article

[Omestes]

and I really think this is quite intuitive - that cats can't be both dead and alive at the same - why is this so hard for people (and especially popular science writers)?

Which brings up a converse point; why should physics be intuitive? We evolved to understand a certain scale, this outside this scale are going to be very strange. Relativity isn't really that intuitive, try to explain all the strange side-effects of that theory to lay people. On smaller scales, quantum mechanics are just as intuitive has relativity... meaning, completely nonsensical to our normal existence. Time does not dilate, objects don't elongate or contract based on relative speed per frame of reference, mass doesn't change... etc... Superposition is a demonstrated fact, just like most of the effects of relativity.

Common sense only applies to the world we evolved to understand. Beyond that, it is completely useless.

Re:Poor article

[Anonymous Coward]

Though I agree that relativity might not be fully intuitive yet, I do think that it's getting there. If you want to explain relativity to lay people I suggest the book "Why does E=mc2" by Brian Cox and Jeff Forshaw.

Re:Poor article

[glwtta]

Which brings up a converse point; why should physics be intuitive?

No one's saying that it is, which is why this experiment takes place at the scale we've evolved to understand: cats are very much intuitive.

Superposition is a demonstrated fact, just like most of the effects of relativity.

Fact is a pretty big word, I'd say it's more of a "well understood mathematical principle", but that's entirely beside the point, which is that superposition does not apply to the macroscopic world.

Re:Poor article

[Omestes]

Fact is a pretty big word, I'd say it's more of a "well understood mathematical principle"...

Nah, it is an observable fact, all the stuff behind it is "well understood mathematical principles". Its place in a theory, the explanations, the (sorry) philosophizing, the weight we hold behind the word, are not facts. I can, with a bit of work, do a dual slit experiment in my living room.

Further more, taken out of context, and the authors actual wishes, Schrodinger's fun little gedankenexperiment borders on religion. Before you raise your hackles, hear me out. Taken as reality, there is no possible way for said observer to ever say whether, or whether not, "spooky" quantum effects killed (or not) the cat. It isn't a falsifiable point, therefore it is a (scientific and epistomologically) meaningless statement.

...but that's entirely beside the point, which is that superposition does not apply to the macroscopic world.

Annoying semantic moment: Theoretically it does apply to the macroscopic world, but in such a small way as to be unobservable. Or, at least, so I understand. IANAQP, but I did specialize in philosophy of science and thus had to dig a bit into it. I only understand a small fraction of the math, and only poked around in sources just beyond popular lay level. If I am wrong, please correct me. Hows that for a disclaimer?

Re:Poor article

[Omestes]

It looks dauntingly complex from a distance... a bit closer it is so elegant and simple anyone can understand it. A bit closer still it becomes even more dauntingly complex.

I suppose this is true of all things, though.

Did it happened?

[4wdloop]

Well, yes and no...at the same time...

Stock Market Application

[s.whiplash]

How long will it be before someone tries to manipulate the stock market with it?

Distance?

[b4upoo]

Was this accomplished over a distance or simply to a near by device? I thought that the phenomena was well studied at very short distances.

Unbelievable.

[cpufrier37075]

No Aussie would waste time on such a project. Wait! Was beer involved?

Claude Shannon

[Anonymous Coward]

I wonder what Claude Shannon would make of this.

Hmm. This doesn't sound pleasant.

[OffbeatAdam]

So, you're going to destroy me, but I'll be fine on the other side? I might be crazy but this sounds like the best sale pitch for a future teleporter. I can just hear Scotty now: "Don't worry Dr. McCoy, we're only destroying you on this end!" That would have quelled his fears.

Re:Hmm. This doesn't sound pleasant.

[isorox]

So, you're going to destroy me, but I'll be fine on the other side?

I might be crazy but this sounds like the best sale pitch for a future teleporter.

I can just hear Scotty now: "Don't worry Dr. McCoy, we're only destroying you on this end!"

That would have quelled his fears.

Who said about transportation of concious living matter?

This is about transportation of information at a high speed. Which can't happen (information can't move faster than light otherwise physicist brains explode)

I have a question about invisible fuel tanks

[CrazyJim1]

When it says information passed between the two points is information, does it mean it changes energy states? Because I think there would be a lot of devices that could be engineered with an offsite energy source instead of having a fuel tank.

Re:I have a question about invisible fuel tanks

[radtea]

When it says information passed between the two points is information, does it mean it changes energy states?

No.

The "thing" that is "teleported" is the quantum state, which is completely different to "teleporting" matter or energy. The state of the "receiver" has exactly the same particle quantum numbers (numbers of photons, electrons, etc) immeiately after the "teleportation" as it does immediately before. As such, "teleporting" a quantum state is completely different from "teleporting" a particle, although for some reason ignorant people keep on claiming otherwise.

The reason why I have used scare quotes around "thing" and "teleport" in the above is that it is misleading and wrong to use unadorned ordinary language when trying to speak about quantum reality, which is not bound by the same rules of non-contradiction and causality that the world of experience are bound by. A quantum state is not a "thing" in the usual sense at all, which is why it can be "teleported" when the nominally classical particles that carry the state cannot.

This is /. so I'll try a car analogy, although classical analogies are always tricky with these things. Suppose you have a red car, and a "car colour teleportation device", and I have a blue car, and you trigger your device, which "teleports" the colour of your car to mine (possibliy destroying your car, or its colour, in the process.) So now, whereas before I had a car, I now have a car that is the same colour as yours (was). Then suppose a really ignorant person came along and said, "Wow, a device for teleporting cars! Let me write an article for PopSci on that!" You'd have pretty much the situation we have.

how fast?

[Anonymous Coward]

How fast is it? Could it be faster
than light (forgive my stupidity but i don't know much about the subject just like any avg reader)

Sounds more like the marketing part...

[Anonymous Coward]

The engineer part of me says "Right, now what? Let's find a use for it and start building another one."

That sounds more like the marketing part of you: "Wow, cool sounding technology. Let's find a way to use it somewhere". I'm pretty sure that the engineer part should think "Okay, here we have a problem we need to solve... I wonder if that new technology from a while back would be the best way to do this or not".

Instant Quantum Communication Is Near...

[Exoman]

Instant Quantum Communication Is Near...

...and far

...and everywhere in between.

And that, son, is all you need to know about quantum communication.

Re:opposite of yo dawg

[TaoPhoenix]

"Yo God sux!"
"I'm gonna kill you!"

It's too bad...

[n30na]

That it doesn't sound like it's useful for actual communication yet. I was my fluid router!

Will an Alligator Gar, or a carp do?

[rts008]

*obligatory:*
We don't have native trout here, you insensitive clod!

from:
Payne(as in 'Pain') County, Oklahoma

BTW, I giggled out loud reading your comment!
Oh, and I endorse your philosophy in this case.

Re:fix

[Darfeld]

Fraking Schrödinger zombies...

Scotty beam me up!

[Anonymous Coward]

YES!

I can't wait until I get my personal transporter platform! Yikes!

almost there?

[georgesdev]

When I look at the picture in the post, I can't help but think that it's still light years away from being on the market.

Re:almost there?

[Anonymous Coward]

This would be a better comment if light years were a measure of time

Bad article detector

[kangsterizer]

popsci URL. Science + popular = 1 bad point
"The team employed a mind-boggling set of quantum manipulation techniques to achieve this, " Cool words to fill the void of content = 1000 bad points

I hate those articles so much.

Utterly pointless article

[tehcyder]

I'm getting fed up with articles on slashdot that seem to be news of a major breakthrough in some field of science, but actually turn out to be nothing of the sort.

I don't want to hear any more about personal cold fusion reactors, time travel machines, personal jetpacks or immortality pills until I can order them online.

Re:fix

[Tsingi]

3 kittens were harmed in making this post?

3 of Schroedinger's kittens died, 3 lived. Who knew his cat was pregnant? Or was it?

(No peeking)

A bit too big to be portable.

[Anonymous Coward]

That thing is a bit to large to carry around attached to my laptop. My tethered Andriod phone is much lighter.

Re:fix

[ae1294]

3 kittens were harmed in making this post?

3 of Schroedinger's kittens died, 3 lived. Who knew his cat was pregnant? Or was it?

(No peeking)

I knew but I didn't show anyone...

experiment is very challenging .. thanks for shari

[Anonymous Coward]

experiment is very challenging .. thanks for sharing

So God DOES play dice with the universe?

[kriegs]

Or is this just the quasi-science that Michael Crichton based "Timeline" on?

yawn

[Anonymous Coward]

This will be useful when it's cheap, compact, and can be used to substitute for a length of Cat5e/Cat6. Slap an RJ45 jack on the side and make it the world's longest zero-lag ethernet cable. Plug a warehouse full of them into switches and peer with a Tier One, and you just invented the ISP that needs neither line-sharing nor last-mile cable laying.