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Quantum Computing Using Traditional Transistors

Posted by CowboyNeal on from the reusing-old-hardware dept.

Ocean Consulting writes "UCLA is reporting progress on the quantum computing front by announcing success in controlling the spin of a single electron using an ordinary transistor." It's been a long road for the researchers involved, and even the project lead, Hong Wen Jiang admits, "...our initial theoretical calculations were very favorable, and gave us confidence to persevere."

21 of 323 comments (clear)

  1. Awesome! by erick99 · · Score: 3, Interesting
    Once they get the cost down for actually reading the the state of an electron this will be awesome. Imagine only needing 100 transistors to:

    "With 100 transistors, each containing one of these electrons, you could have the implicit information storage that corresponds to all of the hard disks made in the world this year, multiplied by the number of years the universe has been around," Yablonovitch said. "And why stop with 100 transistors?"

    That is pretty amazing.

    Cheers!

    Erick

    --
    http://www.busyweather.com/
  2. Secure communications? by agm · · Score: 5, Insightful

    Quantum computing, which holds the promise of nearly unlimited processing power, secure communications and the ability to decode encrypted conversations by terrorists and others, is a significant step closer to becoming a reality today with new research published by a team of UCLA scientists in the journal Nature.

    So which is it, secure communications or communications that can be spied on? It can't be both.

    1. Re:Secure communications? by RidiculousPie · · Score: 3, Informative

      Most encryption algorithms rely on it being easier to multiply numbers than to factorise them. Quantum computers can easily factorise a large number into a product of primes.

      This is how quantum computers can break encryption

      I'm not sure what they mean by the encryption that is secure though; Quantum encrytion as such is completely separate from Quantum computers, it is just a clever method using detection of the polarisation of light.

      The sending computer begins by sending photons in one of four configuations, two each for the x shape and + shape

      The detectors can only tell the difference between the two states if they are detecting using the correct shape.

      The reciever then transmits a list saying which detector shape it used for each bit, and the sender sends back information saying when it was a correct guess, thus establishing a cipher key

      Now, if someone is intercepting the signal, they will not guess the same way as the reciever, thus they wont have the cipher key at the end (I can't remember if they are detectable becuase they screw with the polarisation or not).

      Thus unbreakable crytography.

      [Disclaimer: IANAPhysicist, and I know that because I read The Code Book by Simon Singh. He describes it properly and accurately (both secure cryptography and breaking today's algorithms with quantum computers)]

      --
      ah, mod points ... now where is my crack?
    2. Re:Secure communications? by lenhap · · Score: 4, Informative

      It is secure and it allows encrypted communications to be spied on. What they don't tell you is that the encrypted comunications are encrypted using standard encryption methods around today. Things that can be cracked by exhaustive search.

      Using a quantum computer it can search every possible key simultaneously, cracking the encryption almost instantly. An example to understand this, you are in a building searching for your briefcase. Normal computers would go through every room one by one until they find it. A quantum computer would find the briefcase by existing in every room at the same time, finally settling (existance wise) in the room with the briefcase.

      They also mention quantum cryptography being uncrackable, this is true. If someone eaves drops on communication that is encrypted, it inherently destroys the data. The users will recognize intrusion and the eavesdropper cannot decrypt the message because the data has been destroyed.

      So yes, quantum computers can decrypt normal encryption that can be broken by exhaustive search and they can be used to provide quantum cryptograph which is a theoretically unbreakable form of communication.

    3. Re:Secure communications? by cephyn · · Score: 5, Interesting

      Here's what i never understood, maybe you or someone can help me out...

      if eavesdropping on the encrypted transmission destroys it, couldnt the eavesdropper do so on purpose everytime, effectively jamming all transmission? Little point in having a secure way to communicate if no message can ever get through.

      --
      Moo.
    4. Re:Secure communications? by bigberk · · Score: 3, Interesting
      if eavesdropping on the encrypted transmission destroys it, couldnt the eavesdropper do so on purpose everytime, effectively jamming all transmission?
      Definitely. The main problem with practical quantum crypto communications is this issue of information loss due to noise or tampering. If you could send photons over a lossless link (impossibility) then you guarantee entirely protected communications, or easy detection of tampering/eavesdropping.

      But since real transmission lines (even the best optic fibers) will always lose photons, you have to start adding on complicated processing to deal with the losses. Were the photons lost due to natural causes, or is someone eavesdropping? And if data is duplicated to account for losses, the system can possibly be tricked by an attacker into revealing information. This is a delicate subject and a great cause of complication in the field!

      The communications can also be jammed of course but the focus of the technology is delivering a secure link.
    5. Re:Secure communications? by randombit · · Score: 3, Informative

      My understanding was that this is not true. At best you get the square root of the number of steps that would be required for a non-quantum brute force search. This means that key sizes are effectively halved, but that isn't an insurmountable problem.

      Bingo. Which is why the AES competition required support for 256 bit keys, when even 128 bits is out of reach by any conceivable technology.

      Factoring is one such case, which is why quantum computing spells the death of RSA.

      Not true, necessarily. Shor's algorithm is algorithmically faster than the generalized number field sieve, but there is a constant in there. We don't know how big that constant is, and we won't until we have a quantum computer big enough to run Shor's algorithm (30 qubits or so, IIRC). It's entirely possible that Shor's algorithm is only faster then the GNFS once you hit keysizes of 10,000 bits, in which case it doesn't matter. OTOH, if Shor's algorithm is faster than the GNFS on 256 bit keys, we are, indeed, in some trouble. Of course running Shor's algorithm on a 1024 bit RSA key would take quite a large quantum computer, too.

      And, as you mention, there is no algorithm for compute discrete logarithms much faster than usual on quantum computers. I haven't heard about such an algorithm, anyway. Doesn't mean it doesn't exist, of course.

      Summary: algorithmic complexity is not the sole determinant of algorithm running time.

      In summary, quantum computing is powerful, but not a magic wand that makes all classical encryption schemes invalid.

      Thank you. Every time a quantum crypto or quantum computing store pops up here, the hype level seems to increase by several orders of magnitude. It's really annoying.

  3. Now that's a huge hard drive... by zeux · · Score: 3, Insightful

    From the article:
    "With 100 transistors, each containing one of these electrons, you could have the implicit information storage that corresponds to all of the hard disks made in the world this year, multiplied by the number of years the universe has been around," Yablonovitch said. "And why stop with 100 transistors?"

    Of course, because with 101 transistors you could store as many Library of Congress as there are electrons in the visible universe on a disk the size of 2 square hogs for a duration of up to 3.4256 parsecs.

    Unfortunately, it will take up to as many (1/98742) of year as it took in seconds for Apollo 11 to reach the moon from the launch pad to design such a hard-drive.

    Why is it scientists always use weird units? I have absolutely no clue of what "the implicit information storage that corresponds to all of the hard disks made in the world this year, multiplied by the number of years the universe has been around" actually represents in bytes.

    --
    Iraq: war to save the U
  4. That's weird by Anonymous Coward · · Score: 4, Funny

    The article said something totally different brfore I clicked it.

  5. Hrmm... by Arcanix · · Score: 5, Funny

    I thought about reading the article but will it change if I look at it?

  6. wow! by quelrods · · Score: 3, Informative

    This would be something to help drive down the cost. Quantum computing on the desktop would finally be a evolutionary step in computing. (Up'ing clockspeed constantly and decreasing chip size is not evolutionary.) Though, quantum computing on the desktop probably means time to stop using passwords due to sheer power to brute force them.

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    :(){ :|:&};:
    1. Re:wow! by geekoid · · Score: 3, Insightful

      "(Up'ing clockspeed constantly and decreasing chip size is not evolutionary.) "

      actually, it is evolutionary, just not revolutionary.

      --
      The Kruger Dunning explains most post on /. http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect
  7. Kind of misleading... by 7Ghent · · Score: 5, Informative

    They're actually using pulsed microwave bursts to manipulate the electron's spin, not the transistor itself, really.

  8. Tin Foil Hat Time... by CommanderData · · Score: 4, Insightful

    From the article:
    Quantum computing, which holds the promise of nearly unlimited processing power, secure communications and the ability to decode encrypted conversations by terrorists and others (emphasis mine)

    Take special note of the word others, which should be read as everyone. The government will be falling all over themselves to support this research and inherit a technology that makes encryption virtually useless.

    I'm all for advancing technology, and no doubt quantum computing will be a great leap forward. It's just a shame that our privacy will be sacrificed in the process.

    --
    Urge to post... fading... fading... RISING!... fading... fading... gone.
  9. Secure Communications ... by mdvlspwn99 · · Score: 4, Insightful

    is great. Until the technology becomes ubiquitous enough that even terrorists have access to it. Then what? It's secure...even from us.

    --
    If reality was like Slashdot, most people would be (-1) Redundant.
  10. Quantum terms by Decaff · · Score: 3, Interesting

    I wish physicists would be more cautious in their use of language.

    In the article it states: "The UCLA team succeeded in flipping a single electron spin upside down."

    Considering that the term 'spin' is just a metaphor for a quantum-mechanical property that has no equivalent in our everyday experience, it makes no sense to talk about 'flipping' it, or the spin being 'upside down'.

    Neat achievement though....

  11. I had a Quantum hard drive before by gphinch · · Score: 5, Funny

    "With 100 transistors, each containing one of these electrons, you could have the implicit information storage that corresponds to all of the hard disks made in the world this year, multiplied by the number of years the universe has been around," Yablonovitch said. "And why stop with 100 transistors?"

    I hope this drive lasts longer than the Quantumm Fireball I had.

    --
    in bed.
  12. Re:Terrorism. by emeitner · · Score: 3, Insightful

    Fear sells.

    --
    Guru Meditation #6d416769.21610a21
  13. Implicit Disinformation by reversible+physicist · · Score: 3, Interesting

    Quantum communication is already practical, and provides a secure way to communicate to replace factoring-based encryption, which quantum computation may one day make insecure. The hype in this article, though, is way over the top. 100 electron spins can only encode 100 classical bits. Not one bit extra. Yablonovitch is using a very sloppy way of talking about how hard it is to simulate 100 spins, and making it sound like he's talking about a way to store a lot of classical bits! His "implicit information storage" is nonsense. It's also worth mentioning that quantum computation is unlikely to speed up any computation you care about, unless you like to simulate quantum systems. Fast factoring is the "killer app" that got people excited about this field, but "terrorists" (and the rest of us) can just stop using factoring-based encryption.

  14. I can see it now.... by teutonic_leech · · Score: 3, Funny

    Welcome to Windows Quantum 2006! We crash several ways at the same time!

  15. Intro to Quantum Computing by GogglesPisano · · Score: 3, Informative

    The following link may be helpful for those of us who are a little fuzzy on quantum computing: http://www.cs.caltech.edu/~westside/quantum-intro. html