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Data Storage Science Hardware

Storing Qubits In Nuclei 90

Posted by kdawson
from the now-you-see-it-now-you-still-see-it dept.
bednarz writes "Scientists have demonstrated what is being called the 'ultimate miniaturization of computer memory,' storing data for nearly two seconds in the nucleus of an atom of phosphorus. The hybrid quantum memory technique is a key step in the development of quantum computers, according to the National Science Foundation. An international team of scientists demonstrated that quantum information stored in a nucleus has a lifetime of about 1¾ seconds. 'This is significant because before this technique was developed, the longest researchers could preserve quantum information in silicon was a few tens of milliseconds. Other researchers studying quantum computing recently calculated that if a quantum system could store information for at least one second, error correction techniques could then protect that data for an indefinite period of time.'" Here's the NSF press release with pictures of the apparatus. They claim that this technique is promising because it "uses silicon technology" seems a bit of a stretch — the silicon the researchers employed was a painstakingly grown crystal of extremely high purity.
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Storing Qubits In Nuclei

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  • by Anonymous Coward on Friday October 24, 2008 @02:59PM (#25501509)

    I heard BGC3 has already patented this idea.

  • Everything old is new again.

    • by Krabbs (1319121)
      Worst first post on slashdot, ever?
      • Re: (Score:1, Funny)

        by Anonymous Coward
        Slashdot: where every post can be FRIST PSOT!1.
      • Get off his lawn!
      • by G3ckoG33k (647276)

        Are you new here?

        • by Krabbs (1319121)
          Hahaha... Usually they are either funny, stupid or silly. This just didn't make sense.
          • Much to learn have you, young padewan.

            DRAM, or dynamic RAM would hold it's contents for a short while, requiring "refresh" cycles. These would read the data out before it disappeared, and write it back. A similar mechanism would be necessary for this type of memory -- just like DRAM refresh, hence "deja vu": seen before.

            • by Krabbs (1319121)
              Young padawan? Really? Okay, so I should probably have said it made just enough sense not to be funny. Quantum memory is not a reinvention of DRAM, unless you really don't know what you're talking about. In which case I do see the connection. Hence; not really stupid, not really silly and not really funny.
              • No, it isn't a reinvintion.

                But, the need for refresh is what it shares in common with it, despite being due to decoherence instead of discharge.

                In any case, it wasn't intended to be stupid, silly, or funny, and certainly not first: just a bit obscure, as in *whoosh, flies completely over head*.

  • by courteaudotbiz (1191083) on Friday October 24, 2008 @03:01PM (#25501529) Homepage

    An international team of scientists demonstrated that quantum information stored in a nucleus has a lifetime of about 1¾ seconds

    Just as long as it takes me to c..

    ... compute 2 + 2

  • Nuceli, please! (Score:4, Informative)

    by mutende (13564) <klaus@seistrup.dk> on Friday October 24, 2008 @03:04PM (#25501575) Homepage Journal
    The plural of nucleus is nuclei, please!
  • The first thing I thought was all I need now is a miniturized keyboard and mouse and the worlds smallest lcd screen.
  • by Rene S. Hollan (1943) on Friday October 24, 2008 @03:11PM (#25501685)

    It wasn't so much that we thought "souvlaki" was a latin plural when the dish was clearly of Greek origin that bothered the restaurant owner so much as our constant bickering whether the singlar was "souvlakum" or "souvlakus".

    (with apologies to Wayne and Shuster)

  • Here's the NSF press release

    Anyone else read that as the "Not Safe For [the] Press" release?

  • nucleus = singular
    nuclei = plural
    nucleii = ???
    • by 91degrees (207121)
      plural of nucleius:P
    • Re: (Score:3, Funny)

      by jd (1658)
      Nucleii would be be multiple imaginary nuclei, since they're multiplied by the square root of -1.
    • by denzacar (181829)

      nucleus = singular
      nuclei = plural
      nucleii = ???

      Quantum plural which is plural and singular at the same time?

  • However, this isn't the first time short term memory has been used in computing. I can remember (pardon the pun) memory which had to be refreshed, so I'd imagine using that concept would fix the "short" timespan.

    However, that's not the only important number. What about latency?

    • Re: (Score:3, Informative)

      by John Hasler (414242)

      > However, this isn't the first time short term memory has been used in computing.

      No. There were mercury delay lines, for example.

      > I can remember (pardon the pun) memory which had to be refreshed...

      It's called DRAM (Dynamic Random Access Memory). It's the usual kind.

      • by cheros (223479)

        I must admit I wonder just how much energy is lost in refresh operations. The problem is that nothing static is fast enough to keep up (AFAIK, it's been a while since I entertained myself with computing hardware).

        • by Agripa (139780)

          Did you mean nonvolatile instead of static? Static RAM can be significantly faster then dynamic RAM. I expect that NOR Flash could be as fast as dynamic RAM but the demand just is not there when in speed critical applications you can just copy from slow Flash into faster DRAM and lower the system cost.

    • Well, with the quantum memory you won't know until your data is alive or dead until you open the box. And you're right that latency is relevant, as if it takes longer than 1.75 seconds to read the data it may be difficult to use.
    • I bet that refreshing a qbit will face all kinds of problems... More specificaly, the uncertainty principle forbids refreshing qbits, unless you want them to behave like clasical bits.

      A computer based on this would have to make the hole quantum calculation on 1 3/4 seconds, all the way into a classical result. That would be enough to break RSA if there was a big enough computer, but I guess that isn't enough for everybody. Also, I don't know if it is possible to couple several nuclei and create a computer o

      • More specificaly, the uncertainty principle forbids refreshing qbits, unless you want them to behave like clasical bits.

        Well, I think that's the point. Just really small ones, so we can get a higher data density...

      • by TheSync (5291)

        the uncertainty principle forbids refreshing qbits

        Only if you measure them. You can do quantum error correction using quantum computing itself (see this paper for example [citebase.org]).

        A computer based on this would have to make the hole quantum calculation on 1 3/4 seconds

        Since the coherence time is long (over a millisecond), quantum error correction can allow for almost any calculation. [eetimes.eu]

        • There is another comment down there also pointing quantum error correction, if you reread my post you'll see that I talk about it. It isn't obvious (at least for me) that one can apply quantum error correction on that system, by the same reason that it isn't obvious that one can create a quantum computer from it.

          I guess that if the researches tought that it was obvious how to apply such error corrections, they'd have cited that, so I assume nobody knows how to do that yet. Note that I pointed that somebody

  • How is this new? (Score:5, Interesting)

    by digitalderbs (718388) on Friday October 24, 2008 @03:38PM (#25501981)
    I haven't had time to read the nature article quite yet, but it would appear that magnetic moment coherence information is transfered from electrons, which decohere quickly, to nuclei, which decohere much more slowly. Magnetic moments on nuclei in the solid-state and in the absence of local motions can maintain coherences for minutes to hours -- this is not surprising. However, I can't tell from this summary how this is different from DNP [wikipedia.org], a well established method. Maybe because it was done in silicon?
    • Hi, (I'm an author on this paper). That's a good question. DNP, which is indeed a well-established method, is only able to move the *classical* state of an electron spin into a nuclear spin. In other words, it could move a '0', or a '1', but not the quantum superposition states of the form '0 and 1 at the same time' which give quantum computing its power. And then there's the question of getting the state back...
  • 1.75 Seconds.... (Score:3, Informative)

    by bradgoodman (964302) on Friday October 24, 2008 @04:58PM (#25503077) Homepage
    Sounds like a very short amount of time - but this is longer than a DRAM cell will hold data.

    Throw some DRAM-style refreshing in, and it could be viable at even that lifespan.

    • by Krabbs (1319121)
      Charging it would certainly destroy any quantum information. What you need is a quantum computer to do error correction every 1 sec or so.
  • by jeffb (2.718) (1189693) on Friday October 24, 2008 @11:58PM (#25506727)

    This could be the "ultimate miniaturization of computer memory", if not for the fact that each nucleus is wrapped in 15 electrons and about a trillion times its own volume of empty space. Unless, of course, they've found a way to contain degenerate matter and selectively polarize individual nuclei therein -- and I'm thinking compressing matter to degeneracy would tend to shorten those T1 times pretty substantially.

  • While this is certainly a neat result, calling it the "ultimate miniaturization" is silly press-release-talk. For sure, I know of quantum dots in GaAs approaches to quantum computing that store qubits in few or even single electrons. Though the current approach for GaAs can only store qubits for a few hundred microseconds at best, the storage time for Si/SiGe heterostructures could be as long as a few seconds (that hasn't yet been measured, as far as I know, so a few seconds is just a prediction). Beyond

Fools ignore complexity. Pragmatists suffer it. Some can avoid it. Geniuses remove it. -- Perlis's Programming Proverb #58, SIGPLAN Notices, Sept. 1982

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