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A Quantum Memory Storage Prototype

Soulskill posted more than 4 years ago | from the spooky-action-down-under dept.

Australia 114

eldavojohn writes "An Australian National University project has completed a proof-of-concept storage unit that relies on bringing light to a standstill inside a crystal and then releasing it later for a read-once storage device. There are a few complexities to work out, such as the -270 degrees Celsius requirement to stop the light. And there is an interesting side effect noted by the team lead: 'We could entangle the quantum state of two memories, that is, two crystals. According to quantum mechanics, reading out one memory will instantly alter what is stored in the other, no matter how large the distance between them. According to relativity, the way time passes for one memory is affected by how it moves. With a good quantum memory, an experiment to measure how these fundamental effects interact could be as simple as putting one crystal in the back of my car and going for a drive.' Hopefully this will lead to a better understanding and simple testing of quantum entanglement."

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How much light can the crystal hold? (0)

clone53421 (1310749) | more than 4 years ago | (#32696118)

Real-life neuralizer... (ok, more like blinding people)

3rd shifters of the world rejoice (1, Offtopic)

way2trivial (601132) | more than 4 years ago | (#32696124)

Slow glass is one step closer to existence...

let our circadian rhythms be at peace

Re:3rd shifters of the world rejoice (1)

dintech (998802) | more than 4 years ago | (#32697570)

-270 degrees Celsius requirement to stop the light

Surely on this site we can talk about this kind of temperature in terms of Kelvin?

Re:3rd shifters of the world rejoice (1)

edumacator (910819) | more than 4 years ago | (#32699314)

I like Kelvin. He's a cool guy and all, but what does he have to do with this?

Re:3rd shifters of the world rejoice (1)

afxgrin (208686) | more than 4 years ago | (#32700278)

Well he's the chemical safety guy at my workplace. I wear all the PPE cause I'm new. The cryo-gloves can only handle the liquid helium ejecting from the dewars for about 30 seconds before I start to feel it. That's all I can say on the subject.

*shrug*

Sadly i'm not making any of this up.

Re:3rd shifters of the world rejoice (1)

Khyber (864651) | more than 4 years ago | (#32700274)

We have slow glass. It's called quartz.

On the other hand, it's *TOO* slow. Regular glass is too fast. So what do we have?

But (-1, Troll)

Anonymous Coward | more than 4 years ago | (#32696128)

But will it run Linux

So, no storage, but instant transmission? (2, Interesting)

stanlyb (1839382) | more than 4 years ago | (#32696142)

From you explanation, this device is more like a transmission device, not a memory device? Even better, if you ask me. I am beginning to dream about some fancy, quantum cell phone, untraceable, and extremely secure.

Re:So, no storage, but instant transmission? (2, Interesting)

Locke2005 (849178) | more than 4 years ago | (#32696360)

Also extremely heavy due to the liquid nitrogen cooling requirement, and point-to-point use only. Makes it more of a big walkie talkie than a cell phone.

Re:So, no storage, but instant transmission? (1)

vacarul (1624873) | more than 4 years ago | (#32696568)

walkie-talkie communication: you need two walkie-talkies.
cell phone communication: you need four walkie-talkies; your phone is equivalent with two walkie-talkies.

Re:So, no storage, but instant transmission? (1)

Locke2005 (849178) | more than 4 years ago | (#32697158)

Actually, your phone is only 1 of the walkie talkies; the cellular network provider provides 2; and the person you're talking to provides one. Meaning you can't get true secure communication in a many-to-many configuration; the network between the 2 cellular nodes is still inherently insecure.

Re:So, no storage, but instant transmission? (1)

camperdave (969942) | more than 4 years ago | (#32699352)

That's only simplex communication as well. Double up everything for full duplex.

Re:So, no storage, but instant transmission? (1)

Khyber (864651) | more than 4 years ago | (#32700288)

It is still insecure.
We've already tried addressing this problem in the construction of quantum radios. Despite the ability to build it, it just is not secure any further than direct entanglement between the two devices.

You would need some intermediary, otherwise, we're talking about communication without even speaking or thinking, on theoretical level. Suddenly we just advance millions of years by a mere random thought progression? Not likely. Possible, but not likely.

Re:So, no storage, but instant transmission? (1, Informative)

Anonymous Coward | more than 4 years ago | (#32697126)

Also extremely heavy due to the liquid nitrogen cooling requirement, and point-to-point use only. Makes it more of a big walkie talkie than a cell phone.

-270 C... that's 3 above absolute 0. LN2 isn't going to cut it... the only cryogenic gas that's going to work is liquid Helium.

Re:So, no storage, but instant transmission? (1)

Khyber (864651) | more than 4 years ago | (#32700292)

Liquid Hydrogen or metal hydrogen would do the trick as well.

Physics != technology (1)

mangu (126918) | more than 4 years ago | (#32697528)

Also extremely heavy due to the liquid nitrogen cooling requirement

Actually liquid helium as someone already observed, but never mind which element it is. You are thinking of an insufficiently advanced technology. Let's not confuse technological limitations with physical limitations.

A microscopic droplet of liquid helium is exactly as cold as a whole planet made of liquid helium. The way I imagine a handheld cryogenic device is as a tiny box whose walls are made of multiple layers of Peltier chips [wikipedia.org] .

Re:Physics != technology (1)

Locke2005 (849178) | more than 4 years ago | (#32697748)

Yeah, the cryogenic device is really small and light, but the 200 pounds of batteries you have to carry around to power the Peltier chips are sort of a drag...

Re:Physics != technology (1)

sortius_nod (1080919) | more than 4 years ago | (#32698100)

I think you've missed the point. Physical limitations are only temporary. What's to say a Peltier chip can't be created with high energy efficiencies within the next few years? One that, say, can run on a mobile battery?

Re:Physics != technology (0)

Anonymous Coward | more than 4 years ago | (#32699864)

wireless electricity everywhere!

Re:Physics != technology (1)

Khyber (864651) | more than 4 years ago | (#32700312)

"What's to say a Peltier chip can't be created with high energy efficiencies within the next few years? One that, say, can run on a mobile battery?"

Current material physics and current efficiencies of a Peltier chip, to name only the two main ones.

I've been working at this issue for outdoor hydro for years. Peltier is *NOT* the way to go.

Re:So, no storage, but instant transmission? (1)

Interoperable (1651953) | more than 4 years ago | (#32700364)

It's a matter of the material used. The process requires certain properties of the material but is not restricted to any particular substance. This one requires a cryostat to attain the required properties, but other materials are quite possible. It's a matter of doping the right crystal with the right ions. The technique has also been done in warm rubidium vapor [slashdot.org] with nearly as good efficiencies and, I think, longer storage times.

Re:So, no storage, but instant transmission? (1)

mea37 (1201159) | more than 4 years ago | (#32696522)

I think you must have misread the explanation.

Inforamtion (a 3d pattern of photons) is stored in the crystal; it can later be read, once and only once. That means it's memory, with a peculiar sort of volatility.

I think your comment about communication is based on confusion about how entanglement works. You cannot send information through entanglement.

Re:So, no storage, but instant transmission? (1)

twiddlingbits (707452) | more than 4 years ago | (#32697066)

As I understand quantum entanglement the state of the two electrons (photons) is instantly replicated to the other when a change occurs in one no matter the distance apart. However for this to happen the same "rest state" has to be present. You couldn't have Patten X in one and Patten Y in the other, and expect changes in X to be cause Y to be replaced with X..

Re:So, no storage, but instant transmission? (0)

Anonymous Coward | more than 4 years ago | (#32698740)

Not at all..
Imagine two "entangled" marbles, one red and the other blue. You are blindfolded and told to choose one, the other is to be placed in a capsule and sent to the other side of the galaxy.

You are then allowed to look at your marble. If you see a red one, you know that the other is blue and the other way around. Well In Quantum theory.. by looking at your marble, you transformed it from a state where it was both red and blue into one or the other.. and causing it's partner marble 100,000 light years away to transform into the opposing color.

That's it. You can see it's limitations. There's no way to use this to communicate. Einstein himself was opposed to the idea that this was even an actual phenomenon.

Re:So, no storage, but instant transmission? (1)

supertrinko (1396985) | more than 4 years ago | (#32696860)

Transmission device indeed, Hopefully it's possible to predict how the other crystal will be affected. Solution to interplanetary internet anyone?

Re:So, no storage, but instant transmission? (1)

aBaldrich (1692238) | more than 4 years ago | (#32698436)

How can you have instant quantum transmission when contemporaneity is relative?

Unintended consequences (4, Funny)

The Living Fractal (162153) | more than 4 years ago | (#32696170)

On my computer I have two specific pictures in my library that I've been trying to work with for quite some time. One is a picture of a nice bowl of steaming hot grits. The other a picture of Natalie Portman. Now, is it to be understood that with this new memory crystal technology I could effectively entangle the two? Let me know when Best Buy has them!

Re:Unintended consequences (1, Funny)

Anonymous Coward | more than 4 years ago | (#32696240)

As a side effect of the entanglement the resulting picture will be transported back in time about 10 years where a lone slashdotter will find it, and despite having no idea where it came from make a funny post about it. And a legend will be born.

Re:Unintended consequences (1)

dunng808 (448849) | more than 4 years ago | (#32697596)

Does this explain why the article was tagged with a crock hunter hat and not Einstein's head?

Soory. I don't have much time to troll right now (-1, Troll)

Anonymous Coward | more than 4 years ago | (#32696292)

faggot nigger spic honky dyke chink shitstain

Re:Soory. I don't have much time to troll right no (0, Offtopic)

networkBoy (774728) | more than 4 years ago | (#32696422)

you are a failure of a troll.
You have neglected to insult those from the European mainland: Mic, Guido, WOP, and Frog.
Shame on you troll.

and

you spelled 'Sorry' wrong.

Quantum communication? (2, Interesting)

Locke2005 (849178) | more than 4 years ago | (#32696344)

Spooky action at a distance still seems fundamentally wrong to me. At what speed does information propagate between the entangled particles?

Re:Quantum communication? (0)

Anonymous Coward | more than 4 years ago | (#32696398)

It's instantaneous. There is no speed.

Re:Quantum communication? (5, Informative)

BlueKitties (1541613) | more than 4 years ago | (#32696466)

Spin of entangled particles only has a probability of collapsing into a specific state, i.e. information cannot be transfered.

Re:Quantum communication? (2, Insightful)

mathfeel (937008) | more than 4 years ago | (#32696494)

One cannot transfer information with a fundamentally probabilistic process.

Re:Quantum communication? (0)

Anonymous Coward | more than 4 years ago | (#32696786)

How is it any different from an unreliable transmission medium (say, an UTP cable that runs in a nuclear reactor)? From my interpretation, the loss of a chunk of information (a bit, usually) is determined by the signal-to-noise ratio, which (as far as I am aware) is also probabilistic.

Re:Quantum communication? (1)

FrangoAssado (561740) | more than 4 years ago | (#32698398)

The difference is that with entanglement, there's really no (usable) information being transmitted.

Depending on the interpretation of quantum mechanics [wikipedia.org] you use, you must accept that when one entangled particle is measured, the other is affected by the measurement. There are two points, though:

  • There's no way to control the outcome of the measurement of the first entangled particle -- this means you can't control the effect it will have on the second. So, as I said before, there's no way to transmit information this way with entanglement.
  • There are some interpretations of quantum mechanics (Many-worlds [wikipedia.org] , for example) in which there's absolutely no effect on the second particle when you measure the first. So, whether this "spooky action" (as Einstein called it) actually exists, no one can tell. You certainly can explain things with it, but you don't need to.

Re:Quantum communication? (1)

stanlyb (1839382) | more than 4 years ago | (#32699148)

Also, regarding the before mentioned quantum mechanics, there is a law, saying the sum of all quantum states is a constant. So, if you are able to change/manipulate the state of the first particle, then, theoretically, the state of the other particle must change accordingly. Of course, this is only on theory, but if these guys are really able to do it....imagine the possibilities.

Re:Quantum communication? (1)

FrangoAssado (561740) | more than 4 years ago | (#32700070)

Also, regarding the before mentioned quantum mechanics, there is a law, saying the sum of all quantum states is a constant.

I'm not sure what you mean, are you referring to conservation of angular momentum, which states that in the entangled state, whatever polarization one photon has must be opposite to the other one's? If so, it doesn't imply what you say next:

So, if you are able to change/manipulate the state of the first particle, then, theoretically, the state of the other particle must change accordingly. Of course, this is only on theory, but if these guys are really able to do it....imagine the possibilities.

No, not even in theory. If you manipulate the state of one photon to be whatever you like, the entanglement will be broken, and the other photon will simply "choose" a random state. This does not violate conservation of angular momentum, because you're changing the angular momentum of one photon (at the cost of a tiny change the angular momentum of something else).

So, for the umpteenth time: Quantum Mechanics, being compatible with Special Relativity, does not allow you to send information faster than light, even in theory.

Re:Quantum communication? (3, Informative)

Burnhard (1031106) | more than 4 years ago | (#32696684)

It does? It's pretty hard to get your head around. Using Bell's Theorem, it's possible to say that a unified theory cannot both be local and deterministic. That means you have to throw out one or the other. It also discounts hidden variables as an explanation for non-local effects (I think). So I suppose there's a good reason it's called "spooky"!

Re:Quantum communication? (2, Informative)

mea37 (1201159) | more than 4 years ago | (#32696756)

I've read descriptions of the experiment that is supposed to rule out "hidden variables". It is statistical in nature, and I didn't (probably still don't) have a good enough grounding in the theory to really understand it (as physics isn't actually my field). So I can only say that all the credible texts on the subject claim that hidden variables could not account for what is observed.

It's called "spooky" because that was a term Einstein used to describe his initial dissatisfaction with the theory.

Bells Theorem.....for dummys! (1)

tonywestonuk (261622) | more than 4 years ago | (#32699758)

I couldn't get my head around it either.....until I read this..

http://quantumtantra.com/bell2.html [quantumtantra.com]

puts it into 'simpleish' terms, for non quantium physicists like me!

Re:Quantum communication? (1)

Burnhard (1031106) | more than 4 years ago | (#32696800)

However, as I've just read:

There is a way to escape the inference of superluminal speeds and spooky action at a distance. But it involves absolute determinism in the universe, the complete absence of free will. Suppose the world is super-deterministic, with not just inanimate nature running on behind-the-scenes clockwork, but with our behavior, including our belief that we are free to choose to do one experiment rather than another, absolutely predetermined, including the "decision" by the experimenter to carry out one set of measurements rather than another, the difficulty disappears. There is no need for a faster than light signal to tell particle A what measurement has been carried out on particle B, because the universe, including particle A, already "knows" what that measurement, and its outcome, will be.

Superdeterminism [wikipedia.org]

Re:Quantum communication? (1)

Locke2005 (849178) | more than 4 years ago | (#32696968)

That would be even more evidence that what we interpret as "the real world" is really just a simulation. FTL or even communication is no problem at all for a simulation.

Re:Quantum communication? (3, Insightful)

Burnhard (1031106) | more than 4 years ago | (#32697124)

What do you mean by "simulation"? Simulating what? A real Universe? Which real Universe? And why isn't that real Universe this one, rather than this one being a simulation of a real Universe? The idea that it's a simulation is really the same as saying, "God does it".

Re:Quantum communication? (1)

Locke2005 (849178) | more than 4 years ago | (#32697726)

A simulation of an analog universe. The properties of the universe we experience are just WEIRD... energy, space, and even time are inherently quantized? Spooky action at a distance? The universe expanded at a rate several magnitudes greater than the speed of light shortly after the big bang? The microwave background radiation has the same average energy in all directions? The universal constants aren't constant over time? Light isn't a wave and isn't a particle? All these strange phenomena make more sense in the context of a computer simulation of a universe than they do in the context of a real, analog universe.

Re:Quantum communication? (2, Insightful)

Burnhard (1031106) | more than 4 years ago | (#32698208)

No, they don't. They are what they are only in the context of our limited understanding and the inherent limitations of the tools we have for exploring the nature of the Universe (mathematics). Explaining it as a computer simulation brings nothing to the table in terms of knowledge. It just moves the problem one step further away (as invoking a God would), requiring an even greater more complex entity that itself has to be explained.

Re:Quantum communication? (1)

FrangoAssado (561740) | more than 4 years ago | (#32698206)

Actually, hidden variables are not ruled out, only local hidden variables. For example, Bohmian mechanics [wikipedia.org] is a valid (non-local, hidden variable) interpretation of quantum mechanics.

I agree that non-local effects do seem "spooky", but other interpretations are also hard to accept (to me, at least). Still, I like Many Worlds better than Bohm's.

It's important to remember one thing, though. As long as these interpretations give the same measurement outcomes for any imaginable experiment (as they seem to, right now), you should use the one that fits your problem better: there's no need to decide which one you'll accept and forget about the others.

Re:Quantum communication? (0)

Anonymous Coward | more than 4 years ago | (#32696806)

There is no information transfer. You generate a complementary set of memories. You cart one away and read it. Now you know what must be in the other memory. This isn't any spookier than, say, taking a couple of shoeboxes, having someone glue a coin face-up in one and face-down in the other, then having a researcher take one away and look inside of it. How fast does information propagate to the other shoebox to set the state of that coin?

Mod parent up please (1)

PotatoFiend (1330299) | more than 4 years ago | (#32697286)

This is the clearest (if a little oversimplified) layman's illustration I've seen of what was proven in this paper [arxiv.org] .

Re:Quantum communication? (0)

Anonymous Coward | more than 4 years ago | (#32696874)

No information is exchanged. Basically QM entanglement works exactly like a classical entanglement. If you put one of the gloves of a set in a box, and keep the other one in your pocket, then give the box to a friend who transports it to the other side of the world, then when someone opens the box, he instantaneously knows what glove you have in your pocket, this is not faster then light travel of information, it's at best something describable as faster then light correlation based inference.

The weird thing in quantum mechanics is just that this correlation holds even if you changes the basis along the way.

Re:Quantum communication? (0)

Anonymous Coward | more than 4 years ago | (#32697634)

No information is exchanged.

True

Basically QM entanglement works exactly like a classical entanglement.

False.

Your gloves are equivalent to a pair of quantum systems that have known eigenstates, but whose eigenstates are unknown to the carrier of the box. The box-carrier can discover the state of the other system through observation of the contents of the box and applying simple deductive reasoning. This is because the entire system was pre-prepared!

Quantum entanglement is different, and weird. The weirdness is easy to see: Suppose you have a source of pairs of entangled photons and you send each pair through a set of detectors to see if they are polarized at a particular angle. If both detectors have the same orientation, the results will always correlate, no matter what the actual angle chosen is.

In classical physics, this 100% correlation can only happen IF the source is spitting out pairs of photons whose polarization is either exactly aligned with or exactly perpendicular to the orientation of the detectors. Think about it!

In the quantum world, correlation in measurements between entangled particles is a function of how the particles are observed, and not a function of properties of the particles themselves.

What I have described here is the basis for the EPR Paradox and Bell's Theorem, both of which you should try to grok.

Re:Quantum communication? (0)

Anonymous Coward | more than 4 years ago | (#32697102)

There is no information being propagated between the two. They exist in the same quantum space (which is independent of time and the observable dimensions we are used to).

Light moves really fast, but far slower than slightly less than infinity.

I believe that given two quantum-entangled particles, one stationary in our frame of reference on earth and one moving near the speed of light, there would be a significant time difference observed by us between the two. But the "action at a distance" would be instantaneous (or at least far faster than the speed of light). That would make observed change in the particle appear to come from the past or future (depending on if you were on earth or traveling near the speed of light). Hence, the independence from time.

Re:Quantum communication? (1)

twiddlingbits (707452) | more than 4 years ago | (#32697118)

Speed assumes distance divided by time. There is no time in this case. Look at the May issue of Scientific American. Physicists are starting to wonder if Time really exists in relation to certain states of matter. If time is removed as a variable, the Unified Theory may actually be possible with all this 10 dimensional stings stuff.

Re:Quantum communication? (1)

slaingod (1076625) | more than 4 years ago | (#32697728)

It is 'spooky' correlation at a distance, not action. An analogy: Say you have two balls, red and blue. You have someone put them into black boxes (hidden from you) and give one to you and one to someone else. That other person takes theirs home. When you open your box, and 'take the measurement' and observe you have the blue ball, you 'instantaneously' know that the other person has the red one.

The quantum complication is that while the red and blue balls are in a definite state the entire time due to the infeasibility of isolating a macro-sized object like a ball from all other atoms and photons, the entangled particles are not in a definite state, depending on your interpretation of Quantum Mechanics.

There are 3 major interpretations of quantum mechanics, and this has different implications for each. In the Copenhagen interpretation, the measurement causes the quantum wave function to 'collapse' into a particular state. This is generally where the term spooky comes from, since that came out of the Bohr/Einstein discussions. In the non-local hidden variables interpretation, then some hidden variable that acts non-locally causes actual definite particles to travel through the quantum wave probabilities (ie. the particles where never in an indeterminant state). In the Many Worlds interpretation, the universe enters into a superposition of both basis states (|you observing red, ball is red> and |you observing blue, ball is blue>, you are simply part of the quantum interactions), 'branching' so to speak, but that doesn't affect the fact that in each branch observing red means you know the other is blue and vice versa.

Someone else mentioned Bell's Theorem. Bell's theorem only rules out local hidden variables, not non-local hidden variables. since it is one of the major interpretations in quantum mechanics that is still viable, though those non-local effects can be considered spooky.

Just finished The Teaching Company's QM video series, so blame them :P

Re:Quantum communication? (1)

Warbothong (905464) | more than 4 years ago | (#32698696)

We can describe the particles as communicating instantaneously, but there's no way to harness this since it requires that BOTH particles are in unknown states.

Imagine the following situation: You've got two entangled bits which are opposite, called A and B, and you move them a light year apart. What information can you send?

Let's say someone looks at bit A and it is a 1, that person knows that B must be a 0 since they're opposite, so they radio this to you. You're sat patiently next to B for a year before receiving their radio broadcast, so nothing's travelled faster than light.

Instead let's say that they look at A and it's a 1 and you look at B and it's a 0. Once again, what information has travelled faster than light? None, since you've not exchanged information, you've merely looked at the states of your respective bits, which you brought with you at sub-luminal speed.

Now let's say you try and be more clever; rather than using A and B to store your transferred information, you use an *observation* of A, or a lack of it, at an appointed time to indicate it (eg. "I'll measure A at 11:00 if I mean '1', and won't if I mean '0'). How do we, holding on to B, know whether A has been measured yet? All we can do is look at B and see a 1 or 0, which will happen with 50% probability regardless whether our measurement is first or second.

The crucial points are that 1) we cannot CAUSE either to be a 1 or 0, we can only measure what they are, and 2) to get any information out requires knowlege of measurements of BOTH bits, which must be sent via something like radio which is sub-luminal.

Re:Quantum communication? (1)

EdIII (1114411) | more than 4 years ago | (#32699412)

You say that there is a 50% probability of measuring Side B and seeing a 1 or a 0. I don't see that as a problem. According to the theory here if I modify Side A, Side B must also change right?

Ok....

First, we would have to be making continuous measurements of Side B and placing them into a buffer. You mentioned a specific time. We can't treat it as a storage device, which is why must treat it as a Layer 1 communication medium. Do we think we can "store" data on an Ethernet cable? Of course not. We can however transmit data across it....

That brings me to the second point, which is we are using a half-duplex communication system with respect to a single Side A/B element. Side B cannot do anything but MEASUREMENT. If Side B modifies itself it will only interfere with Side A.

All of our measurements are creating a communications buffer filled with information. According to you, and many interpretations I have read on Slashdot, there is only a probability that any single bit was actually the transmitted bit correct? Some of those bits will be the transmitted bits?

No problem! All we have really done is create a communications system with a considerable amount of noise and resultant bit errors. It's really no different than being on an iPhone with AT&T, but I digress...

We have methods of dealing with bit errors and missing bits. Can we not just apply some error correction protocols here? We should be able to make a full duplex system simply by adding more Side A/B elements and assigning them to a particular role, i.e, transmitters and receivers.

If we have several thousand transmitters and receivers, and we measure it thousands of times per seconds (or perhaps more) we should be able to apply some error correcting protocols and slap ourselves together a nice Layer 2.

I understand a single Side A/B element is not all that useful, but I am wrong in thinking we cannot apply current technology to thousands of them operating together?

Re:Quantum communication? (2, Interesting)

TexVex (669445) | more than 4 years ago | (#32699842)

According to the theory here if I modify Side A, Side B must also change right?

No. That's what the GP's post said multiple times.

Quantum entanglement's strangeness is all about how observations of entangled particles correlate in a way that defies explanation without resorting to time travel, faster-than-light exchange of information, reverse causality, or a deterministic universe.

First, we would have to be making continuous measurements of Side B and placing them into a buffer.

You cannot observe a quantum thing without changing it. This means all subsequent measurements are invalid. Example: you observe the polarization of a photon by passing it through a polarizer and seeing if it hits a detector on the other side. This happens 50% of the time. The process involves the destruction of the photon either way, because it's either absorbed by the polarizer, or by the detector. Boom, no more photon.

Now, interestingly enough, if you put a second polarizer between the first polarizer and the detector, and you orient the second polarizer at exactly the same angle as the first, ythe chances of each individual photon reaching the detector are still 50%. Why? Because after a photon makes it through the first polarizer, it will subsequently pass through any polarizer oriented the same way. The photon has been altered in such a way that it is now polarized to that exact angle. This effect is classic physics, observable to the naked eye with two pieces of polarized glass.

At the quantum level, the results are the same even if you suspend an individual atom and observe its spin with magnetic fields. The first time you detect the atom's spin, its spin becomes aligned with the angle you tested for, and subsequent measurements at that same angle will always give the same result. Your observation changed the object you measured.

It is not possible to observe the precise angle of a photon's polarization. You can only try to pass it through a polarizer and see if it passes through or not. It's the same for spins -- you can test for "up" or "down" along any axis you choose, but you cannot discover any particular axis along which the particle can be said to be spinning. This is the nature of quantum mechanics: it's the place where the math of the universe becomes integral; there are no real numbers there, only whole ones. The Planck length is 1 unit of distance that cannot be subdivided. Photon wavelengths are always in even multiples of the Planck length. Spin is either up or down. Polarization is either "yes" or "no" for any particular angle (or "clockwise" or "counter-clockwise" for circular polarization filters).

According to you, and many interpretations I have read on Slashdot

The problem is, science reporting tends to sensationalize (because dry science is boring to the layman) and journalists tend to misunderstand (because they're writers, not rocket scientists, god dammit Jim!). In the jargon of quantum mechanics, it is understood that to observe something is to change it, and that to determine something is to learn it (not to cause it). So, by simple misunderstanding of the language, it gets reported that by changing one particle (by observing it) you can change its entangled mate (by determining one of its properties by inference). That is quite the sensational misunderstanding! And the fallacy gets repeated until so many believe it that it becomes self-sustaining.

"Instant" Transmission? (1)

bradgoodman (964302) | more than 4 years ago | (#32696358)

Are they saying/implying that the "Instant" transmission breaks the rules of Relativity? (i.e. Faster than Light transmission?)

This would in one sense "break the laws of physics" - but as Quantum Physics and Relativity haven't been unified - one can't necessarily dictate what the other can or cannot do. Is there believe that this is possible?

Re:"Instant" Transmission? (1)

AdamCa (1841392) | more than 4 years ago | (#32696520)

Hey hey hey, Goku managed to do it just fine without any consequence...well except when he did it that time with Cell.

Obligatory XKCD (1)

Maarx (1794262) | more than 4 years ago | (#32696892)

Re:"Instant" Transmission? (1)

city (1189205) | more than 4 years ago | (#32697294)

Sure, it's a consequence of the Copenhagen interpretation of quantum mechanics, the most popular of all interpretations in my layman's understanding. Bohrs and Heisenberg basically went this route, while Einstein wasn't so sure...

Re:"Instant" Transmission? (1)

FrangoAssado (561740) | more than 4 years ago | (#32700186)

Quantum Mechanics and Special Relativity were unified in the late 1920s (see the Dirac Equation [wikipedia.org] ). Special Relativity is what prohibits FTL. So, even in theory, you can not use entanglement to send information FTL.

You're probably confusing Special Relativity (Einstein's E=mc^2 and no FTL signals) with General Relativity (Einstein's Gravity), which is what has not been unified with Quantum Mechanics.

The Standard Model [wikipedia.org] (Quantum Mechanics) says that all forces it explains for sure (electomagnetic, weak and strong) are carried by particles called bosons [wikipedia.org] . This works so well that everyone wants to explain gravity (the force that is not explained by it) by saying it's carried by a particle we have not detected yet, the graviton[1] [wikipedia.org] (it would also be a boson). General Relativity, on the other hand, says that what we feel as gravity is actually just distortion of space-time caused by mass (or energy), and says nothing about the other forces (although I think it works very well with electromagnetism, but I'm not sure).

It's because of this complete difference in the kind of explanation of the forces that it's so hard to reconcile Quantum Mechanics and Special Relativity.

[1] Note: don't confuse the graviton with the Higgs boson, which also has not been detected but is actually needed by the Standard Model in order for it to work the way everyone expects.

Re:"Instant" Transmission? (1)

FrangoAssado (561740) | more than 4 years ago | (#32700216)

It's because of this complete difference in the kind of explanation of the forces that it's so hard to reconcile Quantum Mechanics and Special Relativity.

Oh, crap. It should read "it's so hard to reconcile Quantum Mechanics and General Relativity", of course.

This could form the ultimate DRM (0)

Anonymous Coward | more than 4 years ago | (#32696428)

Read-once media combined with a flatscreen that explodes into a shower of neutrons after a single viewing. And all media outlets have become taco bell and they only sell crappy read-once media and home radiation treatments.

What process is used to release the memory (1)

gsgriffin (1195771) | more than 4 years ago | (#32696596)

...even if the light is stored (paused motion), if the trigger to release the light is not light itself, how much is gained in overall potential for speed. If electrons are used to open or close "doors" to the light, would this be the same end response time as generating the light when needed? Putting theory into practice is fun, but where are they trying to head? Light transistors and memory are great if they are completely light based...otherwise, you are still waiting for the slowest part of the process.

That's one cool car... (1)

mea37 (1201159) | more than 4 years ago | (#32696630)

"There are a few complexities to work out, such as the -270 degrees Celsius requirement to stop the light." ...

"an experiment to measure how these fundamental effects interact could be as simple as putting one crystal in the back of my car and going for a drive."

The back of your car can hold a temperature of -270C?

Re:That's one cool car... (0)

Anonymous Coward | more than 4 years ago | (#32696882)

"There are a few complexities to work out, such as the -270 degrees Celsius requirement to stop the light." ...

"an experiment to measure how these fundamental effects interact could be as simple as putting one crystal in the back of my car and going for a drive."

The back of your car can hold a temperature of -270C?

Also a hell of a nipple erector!

Re:That's one cool car... (2, Funny)

twiddlingbits (707452) | more than 4 years ago | (#32697180)

He has a 1984 DeLorean with the Mr Fusion rigged to power a miniature Liquid Nitrogen plant. Downside is the car can only do 87 MPH.

Re: (0)

Anonymous Coward | more than 4 years ago | (#32696682)

I thought Egon said that crossing the streams was bad.

big physical requirements = big respect (1)

Tumbleweed (3706) | more than 4 years ago | (#32696844)

If we go back to the days where 'mainframes' filled up rooms and required ridiculous amounts of power, etc., I guarantee you the level of respect for our craft would increase. Plus it would bring about yet another generation of technospeak that noone else knows is bullshit, to use in getting PHBs off our backs.

FTL communications (0)

Anonymous Coward | more than 4 years ago | (#32697036)

Can someone please explain this to me ?
If two particles are entangled , modifying one makes the other take a reverse state.
So why can't this be used for transmitting data FTL ?

Re:FTL communications (3, Interesting)

TexVex (669445) | more than 4 years ago | (#32697908)

Because you cannot both entangle the two photons and store information in them at the same time. Entangled quantum particles are by definition in a "superposition of states", which basically means that their values are essentially random when observed.

Storing information in a quantum particle requires observing it, to wrangle it into a desired non-random state. Observation destroys entanglement, because an observed particle is no longer in a superposition of states. Entangling quantum particles requires re-superposing their states. Creation of entanglement destroys information.

So, a pair of these quantum memory cells can store only one of the three following:
1> The same information
2> Unrelated information
3> Entanglement (which is unknown randomness that is correlated between the two cells)

The "spooky-action-at-a-distance" thing is in how the observations of separated but entangled quantum systems correlate. It's weirder than it seems on the surface -- read up on what a Bell Inequality is. That's where the strangeness is; because separate observation of entangled pairs of particles correlates more than is possible by the rules of classical physics and the rules of math and logic.

Future use for CERN, -270 C . . . ? (1)

PolygamousRanchKid (1290638) | more than 4 years ago | (#32697310)

There are a few complexities to work out, such as the -270 degrees Celsius requirement to stop the light.

Isn't that around what CERN keeps the thermostat on its air conditioning set at?

When we find out all that there is to know about particle physics, real soon, we could use the massive cooling systems at CERN to turn the place into a big light stoppage storage facility.

Hell, we could probably come up with some really cool stopping and starting light experiments, as well. I'd pay a high entrance fee to see light stopped!

Top that Mythbusters! I dare you to try to stop light!

Re:Future use for CERN, -270 C . . . ? (1)

ae1294 (1547521) | more than 4 years ago | (#32697966)

There are a few complexities to work out, such as the -270 degrees Celsius requirement to stop the light.

Isn't that around what CERN keeps the thermostat on its air conditioning set at?

Yea it was, but in order to drum up more web-hits they connected the thermostat up to their website using an Arduino. So far no one seems to have noticed but I have the link around here some place if anyone wants it.

Re:Future use for CERN, -270 C . . . ? (1)

stanlyb (1839382) | more than 4 years ago | (#32699318)

The moment you try to see the light stopped......it will continue its route.

Re:Future use for CERN, -270 C . . . ? (0)

Anonymous Coward | more than 4 years ago | (#32699536)

I'd pay a high entrance fee to see light stopped!

just stand in a dark room, the experience would be similar

So you're saying I can stop light? (1)

dbet (1607261) | more than 4 years ago | (#32697422)

No, I'm saying that when you're ready, you won't have to.

That's nothing... (1)

l00sr (266426) | more than 4 years ago | (#32697562)

I've got a quantum memory [wikipedia.org] in my computer right now, in the sense that flash memory exploits quantum tunneling to flip bits.

This is proof that... (1)

turing_m (1030530) | more than 4 years ago | (#32697932)

...there are at least two people who have made it most of the way through Zardoz!

How does this affect the Twins Paradox? (1)

Progman3K (515744) | more than 4 years ago | (#32698390)

I mean if the crystals are entangled and you put one of them on a spaceship and accelerate it to near c for a long enough period, when you change its state, at what moment will the other crystal change?

Quantum Entanglement does not "transfer" anything! (2, Interesting)

CyberBill (526285) | more than 4 years ago | (#32699036)

I am so sick of news reports claiming that if you alter one entangled particle, that the other entangled particle is affected too - like if you push one, the other one moves. IT DOESN'T!

What happens is if you measure the state of one particle, and then you measure the state of the other particle, they are always equal (or opposites, depending on the entanglement type).

Think of it this way... You have a CD burner that burns two CDs at the same time and puts random data on both, but the random data is identical. Obviously, no matter how far away the CDs are, if you read them, they contain the same information. There is absolutely zero information transfer going on here!

Re:Quantum Entanglement does not "transfer" anythi (2, Insightful)

ZDRuX (1010435) | more than 4 years ago | (#32699206)

I'm no physicist so pardon my ignorance but maybe you can help explain. Are we able to change the state of one of these particles at will? And if we are, does the other entangled particle change states as well?

If the two particles simply exhibit a mirror-like effect but we have no way of changing their state, then I agree that this is quite useless at this stage. However, if we are able to change the state of one particle and the other changes as well, then we can have data-transfer (think 1s and 0s, ON and OFF) across limitless distances.

Military would salivate over this a communication channel that cannot be interrupted through regular means like rock and walls, yet is absolutely un-tappable no matter where you are in the universe.

Re:Quantum Entanglement does not "transfer" anythi (2, Insightful)

Your.Master (1088569) | more than 4 years ago | (#32700382)

However, if we are able to change the state of one particle and the other changes as well, then we can have data-transfer (think 1s and 0s, ON and OFF) across limitless distances.

You have hidden assumptions here. We are able to change the state at will, but we are not able to choose what state we change it to, and it's a one-time operation. All you can "communicate" is entirely random data -- which is very useful for quantum cryptography when combined with a classical communications channel, but doesn't have many other evident uses.

Re:Quantum Entanglement does not "transfer" anythi (1)

ZDRuX (1010435) | more than 4 years ago | (#32701816)

I see, it makes more sense now - thanks.

Re:Quantum Entanglement does not "transfer" anythi (2, Informative)

Interoperable (1651953) | more than 4 years ago | (#32700342)

That's incorrect. Remote state preparation absolutely does change the state of a distant particle. For example, consider the case that you have correlated particles such that they will both be measured in the same same state. Each particle is in a superposition of state 1 and state 0 but if one is measured to be a 1 then it prepares the other in state 1 and vice versa. Both particles could be in either state until one is measured, at that point the state of the other is prepared in the state of it's partner. No information is transmitted; however, because the state of the first particle is random anyway.

Read up on Bell's Inequality or the EPR paradox for an explanation of the fact that the state is truly random until it is measured and hence the entangled particle is remotely prepared.

Re:Quantum Entanglement does not "transfer" anythi (1)

Spacezilla (972723) | more than 4 years ago | (#32700734)

Correct, otherwise there would be no "spooky action at a distance", as Einstein put it.

A lot of people explain it like this: You write two notes, one has the letter A on it, the other has the letter B on it. Then you put them in envelopes and mail them to two different people. When one of them gets the envelope, they instantly know what the other person got.

This explanation is incorrect, because there is no letter A or B until either is observed with quantum entanglement.

A better explanation would be: You put two pieces of magic paper in envelopes, without looking at them, and mail them to two different people. When the first person opens their envelope and looks at the note, it will switch from random to display either the letter A or the letter B. The instant it does, it magically instantly tells the other piece of paper to show the other letter. It really does transfer its state faster than the speed of light, we just can't use it to transfer information faster than the speed of light.

Re:Quantum Entanglement does not "transfer" anythi (0)

Anonymous Coward | more than 4 years ago | (#32700844)

And read up on the many-worlds interpretation to see how this can be explained without any need for instantaneous transfer. The instantaneous transfer of information is an artifact of the Copenhagen interpretation of quantum mechanics.

Heisenberg (1)

nickovs (115935) | more than 4 years ago | (#32699488)

The problem with building a memory stick out of quantum memory would be that you'd never be able to know both what's on the thumb drive and where you left it!

Temporal entanglement? (1)

skeftomai (1057866) | more than 4 years ago | (#32700414)

Suppose you have two entangled particles, and you put one in a space ship which travels at relativistic speeds for a while. The ship comes back, and 100 years have passed for the other particle. Would the particles still be entangled? If so, what would happen to the other when one's state changes?

Re:Temporal entanglement? (1)

Urkki (668283) | more than 4 years ago | (#32701790)

Suppose you have two entangled particles, and you put one in a space ship which travels at relativistic speeds for a while. The ship comes back, and 100 years have passed for the other particle. Would the particles still be entangled? If so, what would happen to the other when one's state changes?

You can't set, change or know the state of entangled particles, so question is kind of moot. What happens is, the particles are no longer entangled. Nothing observable happens to the other particle, ie. it can't be known that the entanglement was broken.

Re:Temporal entanglement? (0)

Anonymous Coward | more than 4 years ago | (#32702074)

How do researchers know when two particles are entangled?

Regardless of whether we can measure the particles, what might happen? Could a change of state of one particle cause a change of state of the other back in time?

Down Under, You Say? (0)

Anonymous Coward | more than 4 years ago | (#32701182)

I'd like some "spooky action down under."

Serious question: Faster than light communication? (2, Interesting)

RichiH (749257) | more than 4 years ago | (#32701274)

One thing I always wondered:

Let's say I have a total of 1024 entangled pairs; well contained and stable. Now, I take the one half of those pairs and transport them somewhere else. Then, I proceed to measure the state of them _or not_. When checking the other half, shouldn't I get a total of 1024 "altered" and "unaltered" read-outs, resulting in the transmission of 128 bytes?

Granted, it's still hard to do all this, but afaik, what I just described is FTL transmission of actually useful data.

As I am sure there is some pitfall with which the quantum theories foil FTL plans (they seem to do that pretty reliably), I am eager to learn what trick those pesky laws of physics will pull out of their, admittedly tiny, hat, this time.

Re:Serious question: Faster than light communicati (2, Insightful)

Urkki (668283) | more than 4 years ago | (#32701824)

One thing I always wondered:

Let's say I have a total of 1024 entangled pairs; well contained and stable. Now, I take the one half of those pairs and transport them somewhere else. Then, I proceed to measure the state of them _or not_. When checking the other half, shouldn't I get a total of 1024 "altered" and "unaltered" read-outs, resulting in the transmission of 128 bytes?

You can't measure if a particle is entangled, or if something was done to the entangled pair even if you know it's entangled.

So no transferring information that way, sorry.

Re:Serious question: Faster than light communicati (1)

RichiH (749257) | more than 4 years ago | (#32701896)

If that is the case why do we even know about entanglement in the first place? And why do we care about that fact?

Re:Serious question: Faster than light communicati (1)

Urkki (668283) | more than 4 years ago | (#32702032)

If that is the case why do we even know about entanglement in the first place?

Well, if we have both particles we've ourselves made entangled, and then measure both (in whatever order, , we see that they indeed were entangled.

And why do we care about that fact?

Well, it used to be pretty much basic physics research, but we're approaching the point where we have practical quantum cryptography and then practical quantum computing, and who know what future applications we come up with. Being able to stop entangled light sounds like a pretty nifty building block for future technologies. I don't think anybody looked at the first huge proof-of-concept transistor in a lab and said "hey, I know, people will use technology based on this to write on global discussion forums, while sitting on a beach at the back-end-of-nowhere".

Re:Serious question: Faster than light communicati (1)

RichiH (749257) | more than 4 years ago | (#32702184)

>Well, if we have both particles we've ourselves made entangled, and then measure both (in whatever order, , we see that they indeed were entangled.

So I can prove that the _were_ entangled by a measurement which destroys said entaglement?

> I don't think anybody looked at the first huge proof-of concept transistor in a lab and said "hey, I know, people will use technology based on this to write on global discussion forums, while sitting on a beach at the back-end-of-nowhere".

Point well made & taken.

Marty!...Marty! (1)

BlackBloq (702158) | more than 4 years ago | (#32701612)

"could be as simple as putting one crystal in the back of my car and going for a drive, hitting 90 MPH and one Gigawatt later... fwoosh!"
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