Want to read Slashdot from your mobile device? Point it at m.slashdot.org and keep reading!

 


Forgot your password?
Close
typodupeerror
Australia Supercomputing Technology Science

A Quantum Memory Storage Prototype 114

Posted by Soulskill from the spooky-action-down-under dept.
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."
This discussion has been archived. No new comments can be posted.

A Quantum Memory Storage Prototype More

A Quantum Memory Storage Prototype

Comments Filter:

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

  • Slow glass is one step closer to existence...

    let our circadian rhythms be at peace

  • 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: (Score:2, Interesting)

      by Locke2005 ( 849178 )
      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.
      • walkie-talkie communication: you need two walkie-talkies.
        cell phone communication: you need four walkie-talkies; your phone is equivalent with two walkie-talkies.
        • 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.
          • That's only simplex communication as well. Double up everything for full duplex.

            • Re: (Score:2)

              by Khyber ( 864651 )

              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: (Score:1, Informative)

        by Anonymous Coward

        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.

      • 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].

        • 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...

          • 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: (Score:2)

              by Khyber ( 864651 )

              "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.

      • 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.

      • It's possible to make a quantum repeater (it uses quantum teleportation to move the information without looking at it). Send some classical location data along the quantum encrypted stuff and have the cell tower choose which repeater to use based on the location data, and then you can have more than just point-to-point.

        Aligning your laser with that of the tower will be a major pain, though, and you can't just get around it by sending more than one photon: doing so will void the theoretical uncrackability

    • Re: (Score:2)

      by mea37 ( 1201159 )

      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.

      • 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..
    • Transmission device indeed, Hopefully it's possible to predict how the other crystal will be affected. Solution to interplanetary internet anyone?
    • How can you have instant quantum transmission when contemporaneity is relative?
  • 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: (Score:1, Funny)

      by Anonymous Coward

      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.

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

  • Quantum communication? (Score:3, Interesting)

    by Locke2005 ( 849178 ) on Friday June 25, 2010 @05:01PM (#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? (Score:5, Informative)

      by BlueKitties ( 1541613 ) <bluekitties616@gmail.com> on Friday June 25, 2010 @05:11PM (#32696466)
      Spin of entangled particles only has a probability of collapsing into a specific state, i.e. information cannot be transfered.

    • Re: (Score:3, Insightful)

      by mathfeel ( 937008 )
      One cannot transfer information with a fundamentally probabilistic process.

    • Re:Quantum communication? (Score:4, Informative)

      by Burnhard ( 1031106 ) on Friday June 25, 2010 @05:27PM (#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: (Score:3, Informative)

        by mea37 ( 1201159 )

        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.

        • 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: (Score:2)

            by mea37 ( 1201159 )

            Thanks for the link. That does clarify the material from my previous readings considerably.

            I must admit it still feels like there's a gap in there somewhere, but I'll have to wait until I have some free time to read further on the matter. The immediate question this raises in my mind is: does theory support the idea of more than two mutually-entangled particles, and if so what do we get if three SPOT detectors are used at 0, +30, and -30 mutual angles...

      • 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 c

        • 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? (Score:4, Insightful)

            by Burnhard ( 1031106 ) on Friday June 25, 2010 @05:57PM (#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".
            • 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

              • Re: (Score:3, Insightful)

                by Burnhard ( 1031106 )
                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.
                • Speaking of "invoking a God", how does one explain the creation of the universe, an effect without a cause that seemingly violates the principle of causality, without use of the phrase "and then a miracle happens!"

        • > 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...

          There is nothing "super" about that. If the universe is deterministic then of course our behavior (including our assertions to the contrary) is determined: we are part of the universe. "Animate" nature is not special.

      • 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

    • 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.

    • 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

    • 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 r

      • Re: (Score:2)

        by EdIII ( 1114411 )

        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

        • Re: (Score:3, Interesting)

          by TexVex ( 669445 )

          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 observ

    • AIUI - "Spooky action at a distance" is really a consequence of the Copenhagen Interpretation and may be simply evidence that this interpretation is too simplistic.

      The Copenhagen Interpretation is where we get the idea that when a quantum particle is measured/observed it goes from having an indeterminate state to "collapsing" into a definite state.

      The key thing to realise is when you measure a quantum particle, the detector is always a macroscopic object. The particle interacts with the atoms in the detect

  • 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?

  • ...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 proce

  • "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: (Score:3, Funny)

      by twiddlingbits ( 707452 )
      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.

  • 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.

  • 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: (Score:2)

      by ae1294 ( 1547521 )

      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.

    • The moment you try to see the light stopped......it will continue its route.
  • No, I'm saying that when you're ready, you won't have to.

  • 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.

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

  • 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! (Score:3, Interesting)

    by CyberBill ( 526285 ) on Friday June 25, 2010 @09:26PM (#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: (Score:3, Insightful)

      by ZDRuX ( 1010435 )
      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

      • Re: (Score:3, Insightful)

        by Your.Master ( 1088569 )

        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: (Score:3, Informative)

      by Interoperable ( 1651953 )

      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

      • 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 p

  • 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!

  • 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: (Score:2)

      by Urkki ( 668283 )

      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.

  • Serious question: Faster than light communication? (Score:3, Interesting)

    by RichiH ( 749257 ) on Saturday June 26, 2010 @06:31AM (#32701274) Homepage

    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: (Score:3, Insightful)

      by Urkki ( 668283 )

      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: (Score:2)

        by RichiH ( 749257 )

        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: (Score:2)

          by Urkki ( 668283 )

          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 f

          • Re: (Score:2)

            by RichiH ( 749257 )

            >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

            • Re: (Score:2)

              by Urkki ( 668283 )

              >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?

              Yeah. Which proves that the method to make them entangled works (or tells how reliably it works, statistically). And then that method can be used to create entangled particles for whatever other purposes than just testing if entanglement works.

              It's worth noting that measuring just one pair, and finding them in states where they could have been entangled proves nothing, as there was 50% chance that they were in those states just by coincidence. But when 50% probabilities keep adding up, you can be more and m

              • Re: (Score:2)

                by RichiH ( 749257 )

                So basically I create entangled pairs with probability X and hope they are entangled when I do stuff with them?

                Question is: what are the [envisioned] uses?

                • Re: (Score:2)

                  by Urkki ( 668283 )

                  So basically I create entangled pairs with probability X and hope they are entangled when I do stuff with them?

                  Question is: what are the [envisioned] uses?

                  I don't know if there's anything else practical, except quantum encryption and quantum communication (100% secure, as an eavesdropper would destroy the signal) and quantum computing, and more dense information storage. I think there's some research into quantum compression or "superdense coding", but I don't know if it can produce just 50% compression, or if it's possible to for example use 64 qubits to store 64^2 bits of information, or whatever.

                  In a less cheery note, quantum technology could probably be u

  • "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!"

Slashdot Top Deals

The moon is made of green cheese. -- John Heywood

Close