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Communications Science Technology

Storing Photons In a Solid State Device 68

Posted by timothy
from the next-year-in-vending-machines dept.
bondisthebest writes in with a report from IEEE Spectrum: "Physicists in Switzerland, led by Nicolas Gisin of the University of Geneva, reported last week in Nature that they have made a solid-state device capable of storing photons for as long as 1 microsecond. The invention will aid in the development of light-based quantum-cryptography networks, which are theoretically impervious to hacking but are currently limited in range to a few dozen kilometers, primarily because of a lack of a suitable way to store the quantum state of photons."
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Storing Photons In a Solid State Device

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  • Wow, they've figured out how to store photons for about as long as my three-year-old obeys a command to stop fidgeting.

    From TFA: What they did was "find a way to trap a photon in a collection of 10 million neodymium atoms embedded in an yttrium orthovanadate crystal". Now say that 10 times fast. :-)
    • by pope1 (40057)

      Well, it's a start. As soon as they find a way to refresh the state at a regular frequency we'll be able to store (not just transmit) information with light. I hope it involves the use of tiny, tiny mirrors. =P

      • Re: (Score:1, Insightful)

        by Anonymous Coward

        1 microsecond of persistence...they'd need to be refreshed at a rate of 1GHz, which seems plausible.

        After reading the article, it seems we're still a long long long way off from any kind of general-purpose photonic processor, but this seems like a very important advance.

      • by lgw (121541)

        we'll be able to store (not just transmit) information with light

        That basic idea is hardly new. [wikipedia.org] I'm not sure why you'd want to store information as light, but storage vs transmission is a blurry distinction these days in any case. A modern undersea cable "stores" megabits as light.

    • by Dutch Gun (899105) on Wednesday December 24, 2008 @04:13PM (#26226099)

      I'll bet if you also chill your 3 year old to near absolute zero, you can get him to stop fidgeting for much longer than that.

      Anyhow... *cough*, I had to follow an extra link to see what this might be good for. Apparently, one could theoretically build a quantum repeater, required for quantum networks, which supposedly would be impervious to hacking, because supposedly one can't read the quantum data without actually changing it's state to some degree.

      But then there's this:

      Quantum repeaters will be an essential component for long-range quantum information networks because photons degenerate--their quantum state changes--as they travel and need to be regenerated periodically in a way that preserves their original information. No one has been able to make a reliable quantum repeater yet. One of the prerequisites for such a device is a quantum memory that can store photons (and their quantum state) without destroying entanglement. Entanglement, a property important to quantum networks, allows two photons to be linked in such a way that, if someone measures one of the photons, the quantum state of the other becomes known as well. When a photon travels through optical fiber, entanglement degeneration occurs by approximately 300 kilometers.

      So, if they could somehow figure out how to build a repeater, doesn't that by definition mean they could read the data, then recreate and retransmit it? Or is the act of repeating and retransmitting the quantum data different than "reading" the data? I don't quite understand how this is supposed to work (not too surprising, I'm not a physicist). Can anyone explain this supposed paradox to me?

      • by SmlFreshwaterBuffalo (608664) on Wednesday December 24, 2008 @04:41PM (#26226283)

        I think "reading" is referring to actually retrieving something of value from the data. If retransmitting requires some sort of processing to occur, then the processor would have to read the data in order to retransmit it. But if retransmitting can be done at the quantum level (the goal of this as far as I can tell), then there is nothing actually reading the data, it's merely propagated through.

        A (rather bad) analogy would be if someone were to speak to you in a language you do not know, and you repeated the words (data) verbatim. You retransmitted the words, but did not need to process them (i.e. read the data). That is, you didn't need to know what the words meant to repeat them.

        • by Dutch Gun (899105)

          I think "reading" is referring to actually retrieving something of value from the data. If retransmitting requires some sort of processing to occur, then the processor would have to read the data in order to retransmit it. But if retransmitting can be done at the quantum level (the goal of this as far as I can tell), then there is nothing actually reading the data, it's merely propagated through.

          A (rather bad) analogy would be if someone were to speak to you in a language you do not know, and you repeated the words (data) verbatim. You retransmitted the words, but did not need to process them (i.e. read the data). That is, you didn't need to know what the words meant to repeat them.

          Thanks for the clarification. That makes a bit more sense.

        • So if im not a vet, and i cant tell if the cat is asleep or dead, it is in a state of both sleep and dead until i take it to the vet.

      • There usually are a few touted applications of "slow light".

        As a pulse/beam of light slows down, it intensifies (just like chairs on a chairlift bunch up at the slow top and bottom base stations). As the intensity of the light goes up, so do the nonlinear effects of the medium, so if you want to exploit nonlinearity, slow light is a good thing. However, this particular implementation (requiring neodymium atoms as the medium) won't be useful for this application because I don't think many people are intere

      • by b4upoo (166390)

        So will this tech be able to build a stronger chess computer? Will I ever be able to win?

        • Re: (Score:3, Interesting)

          by Dutch Gun (899105)

          So will this tech be able to build a stronger chess computer? Will I ever be able to win?

          Forget chess. We've already beaten grandmasters with computers. The next AI challenge is programming a decent Go player. [wikipedia.org]

          • So will this tech be able to build a stronger chess computer? Will I ever be able to win?

            Forget chess. We've already beaten grandmasters with computers. The next AI challenge is programming a decent Go player. [wikipedia.org]

            And then after that will be making computers behave like they do in movies.

    • by SinGunner (911891)
      Old joke-answer:

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      that
    • by davidsyes (765062)

      When you store those "photons" in your solid state device, you KNOW when your child first becomes the twinkle in your eye...

    • by b4upoo (166390)

      Is this sort of like finding a way to make memory expensive again? Yeh, I know P.C. Magazine will soon explain why every home PC needs this technology.

  • by Anonymous Coward on Wednesday December 24, 2008 @04:10PM (#26226071)

    ...he said your server was either hacked or it wasn't.

  • by CopaceticOpus (965603) on Wednesday December 24, 2008 @04:11PM (#26226075)

    I just need to be the first to patent two mirrors facing each other...

    • Re: (Score:3, Insightful)

      by Kabuthunk (972557)

      Course, then you're left with the problem of getting the photon to STAY between the mirrors, instead of just go back and forth away from the source until it hits the bottom of the mirror.

      You'd have to find a way to release the photon exactly perpendicular to the mirror, but not have the emitter get in the way when it bounces back.

      • by ArsonSmith (13997) on Wednesday December 24, 2008 @04:52PM (#26226359) Journal

        Here's my initial design blue prints:

        Active Photon Refection and Recapture Matrix [old-wizard.com]

      • I used to be obsessed with this idea when I was a kid (I was a very strange kid). Except not photons, but a beam of light. How can I trap it between mirrors?

        My final idea was to shine a beam of light in a box or sphere of mirrors, figure out a trajectory to keep the light from shining back out my hole for like a second, then shut the lid really quick (which has a mirror to block the escaping light).

        Why couldn't someone have just explained to me the simpler way of solving this problem?

        I.e., go outside and do

        • I always wanted to do something like this, also, but, you know, since I can't move my hands at the speed of light (to close the box) it was just a curiousity.
          • by Hucko (998827)

            I did something similar (made a cube of mirrors) but couldnt figure how to observe the light without letting it out.

    • You're behind the curve when it comes to patent law. Some guy patented mirrors last week. Someone tried to present evidence of prior art, but the judge just saw himself.

    • by gbulmash (688770) *

      I just need to be the first to patent two mirrors facing each other...

      Just don't get a witch between them (read Terry Pratchett's "Witches Abroad" if you don't understand).

  • impervious to hacking. Ba ha ha. Why do they bother with these descriptions? They know they will just be emberassing themselves later.
    • by mark-t (151149) <markt@lynx. b c .ca> on Wednesday December 24, 2008 @05:08PM (#26226463) Journal

      Sure, if somebody finds a way to hack the physical universe in which we live and change its laws of operation, I suppose its possible.

      Quantum cryptography is secure by virtue of actual physical laws. Unless we are all living in the Matrix or some weird-ass crap like that, I'd say it's a pretty safe bet that it's secure. Even the mere _attempt_ to hack it would be immediately obvious to both the sender and the receiver.

      • Quantum cryptography is secure by virtue of actual physical laws. Unless we are all living in the Matrix or some weird-ass crap like that, I'd say it's a pretty safe bet that it's secure.

        Even if we were in the Matrix, it would still be secure. Yes, "the machine" could change physical laws (conceivably), but the machine already runs your life. So it doesn't matter if it sees your dumb bank code. Replace "the machine" with "God" if you are so inclined. Unless the machine/God-figure decides to reveal your

      • by b4upoo (166390)

        Well, God did create all universes as a binary program but then Microsoft patented all possible combinations of binary code. That leaves us in doubt as to whom is actually running the bits.

        • That leaves us in doubt as to whom is actually running the bits.

          Well I don't know about the bits, but I sure know about the bytes. The bites. The strings. You know, string theory. That is, the spaghetti strings. That you bite. They also fly, kind of like a flying monster.

          It sounded funnier in my head.

      • by rubycodez (864176)

        that's assuming the model we call quantum mechanics is actually accurate. maybe it's merely useful for now.

  • Easy. Just get a small black hole. Shoot the photons around the gravity well. They'll last almost forever.
    • Re: (Score:2, Funny)

      by osu-neko (2604)

      Easy. Just get a small black hole. Shoot the photons around the gravity well. They'll last almost forever.

      No problem, we should have the LHC back online this year. :)

  • Why not use it for (Score:3, Insightful)

    by Whiteox (919863) <htcstech@gmai l . c om> on Wednesday December 24, 2008 @05:24PM (#26226539) Journal

    Fast Ram?
    Sounds ideal.
    In fact I may just go and RTFA.

  • by indigoid (3724)

    It's full of stars!

  • I can store a photon for several seconds by sending it through a medium in which the speed of light is different from the speed in the original medium. Maybe I should patent all known mediums that light can travel through as potential storage devices for photons.
    • by Whiteox (919863)

      I can't think of why that won't work, but I'm not a physicist.
      You can extend that model a bit. If you had a series of fast-slow-fast-slow-fast media then why is the light still traveling fast at the end of the chain? What happens to entropy? A loss of velocity must mean a generation of energy somehow. The only thing I can think of is that you won't be getting as many photons out as was going in.

      Can a physicist explain this?
      If Einstein's Theory is correct, that if you accelerate mass to the speed of light, i

      • Actually I can explain: E=h*c/lambda is the energy equation for a photon. If c changes, which is the case here, the wavelength(lambda) would shift accordingly and there would be no loss of energy. There might be some energy lost at the interface between 2 mediums, but not usually if it's set up correctly.

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