Forgot your password?
typodupeerror
Network Science

The First Universal Quantum Network 156

Posted by samzenpus
from the faster-than-fast dept.
MrSeb writes "German scientists at the Max Planck Institute of Quantum Optics have created the first 'universal quantum network' that could be feasibly scaled up to become a quantum internet. So far their quantum network only spans two labs spaced 21 meters apart, but the scientists stress that longer distances and multiple nodes are possible. The network's construction is ingenious: Each node is represented by a single rubidium atom, trapped inside a reflective optical cavity. These atoms communicate with each other by emitting a single photon over an optical fiber. Each atom is a quantum bit — a qubit — and the polarization of the photon emitted carries the quantum state of the qubit. The receiving qubit absorbs the photon and takes on the quantum state of the transmitter. Voila: A network of qubits that can send, receive, and store quantum information. In another, probably more exciting test, the emitted photons were actually used to entangle the rubidium atoms."
This discussion has been archived. No new comments can be posted.

The First Universal Quantum Network

Comments Filter:
  • I have no idea (Score:4, Interesting)

    by Dyinobal (1427207) on Thursday April 12, 2012 @10:29AM (#39657481)

    I have no idea what any of that means! or what it's ultimate implications are technologically speaking but it sounds awesome!

    Anyone care to enlighten me on the subject?

    • Re: (Score:3, Funny)

      by Anonymous Coward

      It means that one day people will learn the difference between its and it's. Ah, to dream....

      • by Anonymous Coward

        Wow, its awesome!!

    • by sycodon (149926) on Thursday April 12, 2012 @10:49AM (#39657809)

      Really, really fast porn downloads.

      • Re: (Score:3, Funny)

        by Anonymous Coward

        But you'll have no way of telling whether a video is Goatse or not-Goatse until you watch it and collapse the state vector.

    • by jd2112 (1535857) on Thursday April 12, 2012 @11:10AM (#39658083)
      It means that traceroute will be able to tell you response times or router addresses but not both.
    • I have no idea what they mean too but to my understanding cause I didn't take any physics class (too busy screwing the girls back then). I think the "ultimate" goal or one of them is to create a zero latency network to any distance.

      Entangled qubits might be able to form the basis of a quantum network with zero latency over any distance, which would make it rather useful for the intergalactic Galnet that will eventually succeed the internet.

    • Well, the researchers have managed to pass around a box containing a cat which is both dead and alive, if that helps any. This is just a prelude to the next step in their research. The next step will be to "special copy" a box, send one box off, then both parties look inside their boxes. If one box contains a dead cat, the other cat must be alive (copy entanglement rule). The idea is that a "man in the middle" would not be able to peek inside a box, because that ruins the box (another entanglement rule), an
  • FTA: In theory, entangled qubits could be the basis of a quantum network with zero latency over any distance, which would make it rather useful for the intergalactic Galnet that will eventually succeed the internet. I'm pretty sure it's impossibly to transfer information faster than the speed of light http://en.wikipedia.org/wiki/No-communication_theorem [wikipedia.org]
  • by BenJeremy (181303) on Thursday April 12, 2012 @10:31AM (#39657525)

    I'll be impressed when they figure out how to harness entangled particles to achieve instant transfer of information over vast distances.

    Imagine a world with no RF generated, yet completely connected. Better yet... imagine the entire solar system or beyond connected with such a network.

    • by Nemyst (1383049)

      Sorry, not gonna happen. You might as well unplug the phone if that's the call you're waiting for.

      Violating relativity is not on anybody's todo list; entanglement has many useful properties, but you still can't break the speed of light barrier with it, and that isn't an implementation issue.

    • by bigtrike (904535)

      "instant" meaning at the speed of light? It's theoretically impossible to transfer information any faster than that.

      • I thought the rule was anything containing mass could be accelerated past the speed of light. The whole point of entangled atoms, was that the state of one atom was changed, the state of the entangled pair changed to match, and that this change was instantaneous. If the 2 atoms could be moved lightyears apart then you could have (even if it's primitive Morse code) instant transfer of information. Because the information has no mass, you are not breaking the light barrier.

        That's the basis of the Ansible [wikipedia.org] in E

        • by bigtrike (904535)

          IIRC, anything with mass can be accelerated to the speed of light with an infinite amount of energy. Anything without mass has a maximum speed of the speed of light.

          • "anything with mass can be accelerated to the speed of light with an infinite amount of energy."

            Except e = mc2 suggests that were you to do so the object being accelerated would acquire an infinite mass.

            And would so consume the universe.

            "Anything without mass has a maximum speed of the speed of light."

            Also, anything without mass would have a minimum speed of the c. The slightest force it received would cause it accelerate at maximum (infinite) acceleration.

            f = ma, so a = f/m, so possibly it would cause infi

        • This is the angle I'm thinking. Information has no mass so there for it should not be affect by relativity. Please explain how I'm wrong.

          No, really explain how I'm wrong. I would rather know I'm wrong about something to keep thinking it was right.

          • I can't explain it very well, but here's the Wikipedia article on it https://en.wikipedia.org/wiki/No-communication_theorem [wikipedia.org] . It's generally thought of to be true (no contradictary experimental results), but it's not totally certain.

            One way to think about it is that to send information faster than light will break causality and that leads to loads of paradoxes.
            • Okay, I think I understand from reading the article and the comments here. You can't entangle the particles and use them to send information because the process of reading the information changes the state of the particles. Its the Heisenberg uncertainty principal at work. For some reason I didn't put these two together just now.

              Can't we just couple up the Heisenberg compensator and call it good?

      • by Lumpy (12016)

        Define speed of light.

        If you are measuring a distance in 3D space and the time it takes? yes.

        If quantum entanglement exists in 5,6 or even 7D space, the entanglement distance may not be anywhere as far as the 3D space distance.

        Therefore it IS possible in relation to the observer and based on 3D space constraints to transmit information faster than the speed of light without violating Causality.

        • Define speed of light.

          If you are measuring a distance in 3D space and the time it takes? yes.

          If quantum entanglement exists in 5,6 or even 7D space, the entanglement distance may not be anywhere as far as the 3D space distance.

          Therefore it IS possible in relation to the observer and based on 3D space constraints to transmit information faster than the speed of light without violating Causality.

          Wow you're dumb.

          Imagine a 2D plane. Imagine 2 points, A and B, on that plane. They are X units apart.
          Find a path from A to B whose length is shorter than X. Feel free to use as many dimensions as you want.

          Furthermore, there is exactly zero evidence that more than 3 spatial dimensions exist.

          • If you're allowed to use more than 2 dimensions, fold the plane over on itself so that points A and B touch. Now the distance is zero.

            • If you're allowed to use more than 2 dimensions, fold the plane over on itself so that points A and B touch. Now the distance is zero.

              Okay then, have fun folding space at a rate faster than the speed of light.

          • by Thing 1 (178996)
            It helps to be civil, especially when attacking someone with greater knowledge.
            • It helps to be civil, especially when attacking someone with greater knowledge.

              No it doesn't, idiots like him (and you) will continue to be idiots, and think that they're right, despite being completely and totally wrong.
              The comment isn't for him, it's for others who may see his post.

              It is fundamentally impossible to transmit information faster than the speed of light. Using extra dimensions doesn't help. If you want to compress space you'll have to do so at a rate faster than the speed of light across a path that is longer than the initial distance and that traverses the initial di

              • by Thing 1 (178996)
                I hope you get help. You maintain that it is "stupid and impossible" to bend a piece of paper back on itself so that your expressed two points A and B then have no distance between them? And, yes, we will take your challenge and attempt to "fold space faster than the speed of light"; that is what experiments with other dimensions are for. My AC sibling and I agree, you need both tutoring and charm school.
          • by Lumpy (12016)

            "Wow you're dumb."

            Says the kid that cant think. GO back to Geometry 101 kid.

    • by ceoyoyo (59147)

      Why not just imagine instant, and free, teleportation? Both violate the lawsof physics as we know them.

  • Quantum Internet (Score:5, Interesting)

    by pablo_max (626328) on Thursday April 12, 2012 @10:33AM (#39657555)

    I am no physicist, so I am actually asking seriously to those of you who are.
    As it is already know, particles which are entangled at the quantum level have an instant and equal reaction on one another regardless of distance. Would it not be possible to use this "Quantum Internet" for C from say, a satellite controller a rover on Mars and one on Earth?
    I have heard that it is not really workable, but is that from an engineering prospective or from a laws of physics perspective?

    • by Anonymous Coward

      Suppose you have a rover on Mars and a rover on Earth, and the question is whether they should go North or South. With quantum entanglement, you can say "go the same way!" and both rovers will instantly go the same way, or you can say "go different ways!" and both rovers will instantly go different ways. But when you do this you can't control which way a particular rover is going, which will be random. You only control the "xor" of the two directions.

    • by tnk1 (899206)

      The problem with using this for FTL is what is known as the no-communication theorem. The quantum state of two entangled particles will change faster than light (instantly, actually), but you will never be able to control what state that the particle switches to when you make the change because of the way quantum mechanics works.

      For instance, I separate two entangled particles and then proceed to start altering the state of one of them. I know I can change the state, but I do not know what the value of th

      • by atisss (1661313)

        However, since I was unable to predict what state the particle will be in when it is changed, the other side cannot tell if the change was due to transmission or just some random event. Thus, your message arrives faster than light, but no one can read it, or even realize that there even was a message sent to begin with.

        If the state changes are truly random, you can work by detecting non-random anomalies in state, and build an information transmission scheme around it.

    • by FridayBob (619244)

      ... particles which are entangled at the quantum level have an instant and equal reaction on one another regardless of distance. Would it not be possible to use this "Quantum Internet" for C from say, a satellite controller a rover on Mars and one on Earth? ...

      It would be cool, but a quick search shows that the answer is apparently No. It seems two entangled atoms are like two coins that mirror each other such that if one is tossed, the next time the other is tossed it will show the same value. It's weird, but it can't be used for communication, something that also prevents causality from being violated.

    • by Strilanc (1077197)

      Entanglement allows you to instantaneously share a bit of information, but doesn't let you control what the bit will be. This makes it useless for most communication tasks.

      That being said, entanglement can allow coordination in a way that is similar to communication. Check out the Wikipedia article on "quantum pseudo telepathy".

  • Doesn't the Heisenberg Uncertainty principle kind of say that when these machines are determining spins of particles, that they cause them to change? ie entropy?
  • by melonman (608440) on Thursday April 12, 2012 @10:43AM (#39657707) Journal

    From TFA, this is apparently a huge improvement on previous attempts, but it's still not exactly dazzling. What sort of self-correcting protocol do you need to handle 499 of every 500 bits being lost?

    • by PIBM (588930)

      Sending 500 times the exact same information would fix your specific problem... =)

    • by Luyseyal (3154)

      I guess we won't discuss the state-of-the-art in neutrino communication, then...

      http://www.technologyreview.com/blog/arxiv/27648/ [technologyreview.com]

      These guys used an experiment called NuMI (NeUtrino beam at the Main Injector) to generate an intense beam of neutrinos. The beam consisted of about 25 pulses each separated by 2 seconds or so, with each pulse containing some 10^13 neutrinos.

      The beam is pointed at a detector called MINERvA weighing about 170 tonnes and sitting in an underground cavern about a kilometre away. To reach MINERvA, the beam has to travel through 240 metres of solid rock.

      MINERvA is one of world's most sensitive neutrino detectors and yet, out of 10^13 neutrinos in each pulse, it detects only about 0.8 of them on average.

      Nevertheless, that's enough to send a message. The FermiLab team used a simple on-off protocol to represent the 0s and 1s of digital code and transmitted the word "neutrino".

      The entire message took about 140 minutes to send at a data rate that these guys later worked out to be about 0.1 bits per second with an error rate of less than 1 per cent.

      -l

  • by fatphil (181876) on Thursday April 12, 2012 @10:45AM (#39657745) Homepage
    You can't copy quantum state. The only way it can carries the quantum state of something is if it also destroys that something's quantum state. (But of course you can't destroy quantum state either, you've effectively just swapping quantum state.)

    So information might be passed around, but it's never actually being shared.
    Which isn't much of a network.

    Disclaimer - I'm rusty.
  • Sounds like it's going to be a pretty gigantic leap to go from this experiment to an entire Internet. Keeping in mind that they only sent, received, and stored one bit, from one persistent store to another, each of which was capable of store who knows how many bits.

    One bit.

    How many bits (not bytes, bits) make up an "internet"?

    +1 internets to anybody who can give a reasonable answer.
    • How many bits (not bytes, bits) make up an "internet"?

      Why, eight times the number of bytes of course. Did I win teh internets?

  • "Hey Bart, pass me another 500ft spool of that rubidium!"
    • by Anonymous Coward

      That's nothing. I used to have a Quantum hard drive.

  • So basically we could have one of these nodes orbiting Mars and communicate with it instantaneously when actually the node orbiting Mars is 18 minutes or more ago but it could communicate to our past the same way..... Oh dear my head just exploded!
  • If this is really a quantum network, why do they need a fiber to send the information!!!!!!!!!!!!!
  • to read the quantum version of Slashdot.

  • Still no ansible [wikipedia.org] I guess.
  • Ritter acknowledges that the new work is simply a prototype, and one for which numerous improvements are possible. For instance, the transfer of a quantum state between labs succeeded only 0.2 percent of the time, owing to various inefficiencies and technical limitations. "Everything is at the edge of what can be done," he says. "All these characteristics are good enough to do what we've done, but there are clear strategies to pursue to make them even better."

    I wish I could publish a 0.2 % yield, or an experiment that worked 0.2 % of the time in Nature! Clearly I'm in the wrong field (but in all serious, getting atoms to communicate through a fiber optic cable is pretty freaking cool.)

    • Hey as long as it can be made to work reliably it's still a link, not unlike a range-limit wifi connection with a ton of dropped packets.

  • I was under the impression that no interactions of QM go FTL. But a lot of posts have been saying that collapse is basically instantaneously. If this is the case than a encumbersome form of FTL communication could be made. Instead of measuring the states, just use positioning. Like optimise the signal so that you can send your message in a byte, then arrange it so each molecule is arranged like a normal binary number of 1s and 0s. Then send a message by just collapsing the corresponding bits. I suppose that
    • by Fned (43219)

      Then send a message by just collapsing the corresponding bits.

      The bits don't collapse until they're measured, which destroys the entanglement. You can't watch the bits to see if they collapse on their own, because you can't observe them at all without destructively measuring them. All you know for sure is that when someone else measures their entangled bits, they'll get the same pattern you did when you measured yours.

      You can use it to send a message and know that the first person to read it will be the only person that will be able to read it.

  • Maybe the explanation is in TFA and it went over my head but are the two atoms actually quantum entangled? The process seemed to me more like ordinary synchronization. One photon carrying information (at exactly the speed of light, natch) from one of the atoms to the other, somehow making the quantum value of the recipient the same as the value of the sender at the time it was sent. Isn't "entanglement" more that a copy-and-assign?

    Not that maintaining the total information in a qbit over a link could not b

A sheet of paper is an ink-lined plane. -- Willard Espy, "An Almanac of Words at Play"

Working...