Slashdot is powered by your submissions, so send in your scoop

 


Forgot your password?
Close
typodupeerror
×
Supercomputing Science Hardware Technology

First 'Quantum Computer Chips' Demonstrated 171

Posted by Zonk from the just-like-magic dept.
holy_calamity writes "The first quantum computer chips have been made by two US groups, New Scientist reports. Both NIST and Yale have demonstrated chips where information was transferred between two superconducting qubits using a 'quantum bus'. The bus is made from a cavity that traps a single microwave photon as a standing wave — the NIST group also managed to use the bus to store data from one qubit for a short time. 'After encoding information in one qubit, they transferred it into the cavity for 10 nanoseconds before transferring it to the other qubit. Yale's chip used qubits around 1-micron square built on silicon, while NIST used larger 10-square-micron qubits on top of sapphire. In both prototypes, the bus between the qubits was between five and seven millimeters long.'"
This discussion has been archived. No new comments can be posted.

First 'Quantum Computer Chips' Demonstrated More

First 'Quantum Computer Chips' Demonstrated

Comments Filter:

  • First... Or not (Score:5, Funny)

    by Lectoid ( 891115 ) on Thursday September 27, 2007 @09:04AM (#20767999)
    maybe I'm first, maybe I'm not.

  • Argh! (Score:3, Funny)

    by Cleon ( 471197 ) <<moc.oohay> <ta> <24noelc>> on Thursday September 27, 2007 @09:05AM (#20768015) Homepage
    Must...Not...Imagine....Beowulf...Cluster....

    • Re:Argh! (Score:5, Funny)

      by Anonymous Coward on Thursday September 27, 2007 @09:14AM (#20768145)
      What if you put a cat inside that Beowulf cluster you're not imagining?

    • Re: (Score:3, Interesting)

      by Tyler Durden ( 136036 )
      If I understand it correctly, a Quantum Computer already is a Beowulf Cluster of possibilities.
      • So creating a Beowulf cluster of these.. would be like a Beowulf Squared! Do you think you could then produce a Beowulf Cube of them?

    • Re:Argh! (Score:5, Insightful)

      by tinkertim ( 918832 ) on Thursday September 27, 2007 @10:28AM (#20769181)
      Why is it things like this never have pictures? I wanna see pictures. Its no fun to read about things that you don't (quite) understand unless you can ooh and ahh at pictures while you pretend to understand. Then you can point at your screen and say "See? Its THAT piece. That's what makes it work. Its the, err.. umm, thing that makes it work!"

      • Re: (Score:2, Funny)

        by nschubach ( 922175 )
        ...or at least a fancy lab with blue under desk lighting and neon plexiglass walls with blacklights. I mean, seriously.
        • You watch way too many movies. Real labs look like messy garages, with the occasional cylinder with lots of bolts and wire thingies sticking out. There are drawers, hopefully labeled, filled with miscellaneous equipment, and perhaps a scarred work-table, stained from chemicals and charred from solder misses. If there is a desk, it's piled high with notes, books, and papers (to be written or read).
      • There is a picture, it's just that you need a quantum nanoscope to view it. And when you look at the picture, it changes anyway.. just like those damn flash adverts
      • here is a picture for you

        2

  • The Universe (Score:5, Funny)

    by MyLongNickName ( 822545 ) on Thursday September 27, 2007 @09:06AM (#20768033) Journal
    Howdy. I don't claim to understand all of this. However, the more I read, the more I am convinced the universe makes no sense. I am waiting for the guy who is dreaming all of this to wake up and for all of us to stop existing.

    • Re:The Universe (Score:5, Insightful)

      by gardyloo ( 512791 ) on Thursday September 27, 2007 @09:13AM (#20768131)
      # "And anyone who thinks they can talk about quantum theory without feeling stinky hasn't yet understood the first thing about smell."

      # "If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet."

            --Neils Bohr
    • the more I am convinced the universe makes no sense

      Congratulations. You're starting to understand. ;)
    • You're not the only one.

      http://www.simulation-argument.com/ [simulation-argument.com]

      This guy has "proof" that we are living in a simulation.

      This could explain where the aliens and time travelers are. They're just not part of the simulation.

      Ok, you self described hackers. Find the bugs in the universe and viola, you can do anything you want.

    • Re: (Score:2)

      by TexVex ( 669445 )

      However, the more I read, the more I am convinced the universe makes no sense.

      It all comes down to what entanglement demonstrates about the nature of reality. In order for it to fit into a consistent framework, you have to choose between a deterministic universe or a universe full of temporal paradoxes. This is why you get quasi-religious philosophical crap like Many Worlds (Seriously -- there are entire other universes constantly splitting off from "this" one that we'll never be able to interact with

      • As for me, I'm pretty sure that the universe is deterministic and so I must simply try to enjoy my illusion of free will.

        Ah, but what does 'try' mean in a deterministic universe? You'll enjoy your illusory free will, or not, regardless of any effort you think you're making. :P

        Here's an interesting third option - suppose the sum-of-all-universes that we live or could live in is a static, 'finished' if you like, multidimensional object, that can be read like a CD. Your point of view is simply like a read head that allows 'you' (assumed to exist separate from this universe) to inspect any given point in space/time/wherever,

        • Re: (Score:2)

          by lazyl ( 619939 )
          'you' (assumed to exist separate from this universe)


          You can come to any conclusion that you want if you start with the necessary assumptions. This one is way out there.

  • Sure sounds nice... (Score:5, Funny)

    by darthflo ( 1095225 ) on Thursday September 27, 2007 @09:14AM (#20768147)
    ... but will it run Linux? (Or will it run and not run Linux at the same time?)

  • Neat things about the quantum bus (Score:4, Funny)

    by Anonymous Coward on Thursday September 27, 2007 @09:16AM (#20768185)
    You can't know how many cats wide it is or fast it is until you transfer data over it.
    • Libraries of Congress, Volkswagens.. and now cats?!?

      I'm telling you, I am detections signs of a revolution being started right here at ./ ;D
  • This has got to be an awesome project to work on...I'm jealous.
    • Well, 24 years ago, right out of high school, I worked at NIST Boulder (then NBS) in the quantum cryoelectronics lab, where they were first starting to play with Josephson Junctions and SQUIDs that are the building blocks of quantum electronics.

      Yes, it was nerd heaven. It was fascinating work, in a pure research environment that I haven't seen since I left CU. But at the time, it didn't seem rewarding, because I was being given "educational" projects, and I wanted to contribute. I did not know that the

  • that stuff like this is the "glue" behind the universe, and someday, some scientist in a lab is going to have an experiment go horribly wrong?

    .. know anybody in Hollywood?

  • Encryption? (Score:4, Interesting)

    by bucky0 ( 229117 ) on Thursday September 27, 2007 @09:20AM (#20768255)
    Once quantum computers become mainstream, what will we use for encryption? Are there algorithms that are computable by standard computers but are also unbreakable using quantum computers?

    • Re: (Score:2)

      by Aladrin ( 926209 )
      I think you asked that backwards. Let me fix it:

      Are there algorithms that are computable by standard computers but are not also unbreakable using quantum computers?

      There ya go.

      Why do you think they're magic and will be able to just run encrypted stuff through them and it's broken with no effort?

      • Re: (Score:2, Informative)

        by BlowHole666 ( 1152399 )
        I think what he was getting at is factoring a number quickly is very slow (np-complete) on todays hardware. With Quantum computers the problem does not take as long just like the NSA and some research groups try and break current encryption with a grid of computers because they just brute force their way past the encryption. The reason your average joe does not do this is because most people can not afford a large grid of computers. Well with quantum computers your average joe may not need a large grid of c

      • Re: (Score:3, Informative)

        by krog ( 25663 )
        Because, in theory, quantum superposition can be exploited to provide keys of arbitrary length; since each qubit can be 0 and 1 simultaneously, put enough qubits together and you ALWAYS have the right key.

        The quantum chips TFA references are not designed around this principle, so this is all a little unrelated, but there is a reason why people expect widespread quantum computing to bring about the end of the useful life of today's ciphers.

        • Re: (Score:2, Funny)

          by Rhaban ( 987410 )

          Because, in theory, quantum superposition can be exploited to provide keys of arbitrary length; since each qubit can be 0 and 1 simultaneously, put enough qubits together and you ALWAYS have the right key.
          But enven if you find the right key with this method, you can't use it because it would change the key the file was encrypted with.

          • Re: (Score:3, Interesting)

            by krog ( 25663 )
            If you're referring to the fact that observing the quantum register will destroy its state, you're right. But the part you're not mentioning is that there is a high probability you just observed the right answer. Measure it a few times -- or a few hundred or thousand, hell with it, that part's still O(1) -- and you can poll for the right key.

            If you think that trying to crack the key with which a file was encrypted will re-encode the file with a different key, I can't help you there.

        • Re:Encryption? (Score:5, Informative)

          by kmac06 ( 608921 ) on Thursday September 27, 2007 @11:03AM (#20769701)
          No, this is not correct. While it's true that if you put N qubits together in the correct superposition, you can make a state that is "equally spread out" over all 2^N possibilities, you cannot make the computer "favor" the correct one (at least not in the sense you are implying). Using Shor's algorithm [wikipedia.org] you can factor a number in O((log N)^3), which is an exponential improvement to crack RSA. And yes, I am a physicist working on quantum computing.

          • Re: (Score:2)

            by arrrrg ( 902404 )
            you cannot make the computer "favor" the correct one (at least not in the sense you are implying)

            In case anyone's interested, making the computer "favor" the correct one is essentially how Grover's algorithm [wikipedia.org] works (IIRC). The problem is that you can only increase the probability of the correct answer(s) by a small factor per iteration, so it can still take 2^(N/2) steps to get an answer ("quadratic speedup"). Moreover, it's been proven that this is the best a QC can do with any similar "general-purpose

      • Re:Encryption? (Score:5, Interesting)

        by carleton ( 97218 ) on Thursday September 27, 2007 @09:51AM (#20768649)
        To clarify both sides, unless I've missed something in the last couple of years, AES was designed[1] with the possibility of quantum computing in mind and the solution is to use double the bit length you'd otherwise need (which is the same for at least some elliptic curve-based Public Key algorithms but for different algorithmic reasons). Is this still computable by standard computers? Yes. Does it make it harder to use "strong" crypto in limited hardware, a little. Could there be improved algorithms down the road that push it to the point that it takes the same order of time to decrypt on standard computers algorithms knowing the key as it does to decrypt (break) on quantum computers without knowing the key? Possibly (in the sense that I don't know of any proofs showing limits on efficiency gains etc.).

        [1]Designed is probably not the right word, but basically, brute force searching of 128bit symmetric keys is believed to be secure in the sense that using all atoms as non-quantum computers would find it some point after expected heat death of universe. However, quantum computers can (being lazy, start at wikipedia's entry on cryptoanalysis, look for grover algorithm) do a brute force search in quadratic time (so 128bits would take on the order of 2^64 steps which is much more tractable... however, using 256bit AES keys (which would otherwise be overkill for most things) now take on the order of 2^128 steps which again hits that whole heat death thing, unless either a better algorithm comes out or someone comes out with some sort of hyper-quantum-computing idea)
         

        • Re: (Score:2)

          by kmac06 ( 608921 )
          Grover's algorithm is the "worst case" scenario in terms of how a quantum computer could search for the solution, but that doesn't mean a faster algorithm can't be found (i.e., Grover's algorithm could be used to factor large numbers, but Shor's algorithm is faster).

          Also, and more importantly, AES is not public-key cryptography, so it can't be used to send encrypted information unless the two parties already have a shared key.
      • Nope - he had it right, you have it backwards.

        He wants to know if there are encryption algorithms that ordinary computers can run that are UNBREAKABLE by quantum computers, i.e. normal encryption that's safe from quantum computers.

        And yes, there is. Quantum computers are good at breaking encryption that relies on a simple mathematical transformation using a big key. This applies particularly to public key ciphers (e.g. RSA). Block and stream ciphers on the other hand rely on doing complex serial, arbitra

    • Re: (Score:2, Insightful)

      by lakiw ( 1039502 )
      Well, there's always one time pads...
    • Most encryption is just based on large prime numbers. So if quantum computing lives up to it's promises, it'll be able to eat common 128 and 256 bit keys for breakfast. Is this a problem? Not really.

      They'll just increase the key size to the point where it won't be easy for even a quantum computer to decrypt...Since there is no theoretical limit to the size of the key, and the only practical limit is processing power, this is almost trivial.

      • Re:Encryption? (Score:4, Insightful)

        by DragonWriter ( 970822 ) on Thursday September 27, 2007 @09:52AM (#20768683)

        They'll just increase the key size to the point where it won't be easy for even a quantum computer to decrypt...Since there is no theoretical limit to the size of the key, and the only practical limit is processing power, this is almost trivial.


        If encryption doesn't scale better than decryption, then there is a problem, since then (at best) someone with K times your processing power (for some value of K that is independent of key size) will be able to decrypt your transmission as easily as you encrypt it, no matter how many bits you use for the key.
        • Generating the key is work, but encryption is relatively easy...You know the key, so it reduces to simple math. Decryption is the exact same process if you have the key.

          Otherwise you have to do that same math with every possible key, which means that every bit that is added to the length of the key doubles the key space, and drastically increases the number of computations a computer would need to try to brute force the key.

          In that sense, encryption scales far better than brute force decryption. The questio

          • Otherwise you have to do that same math with every possible key, which means that every bit that is added to the length of the key doubles the key space, and drastically increases the number of computations a computer would need to try to brute force the key.

            Well, assuming that you need to do a brute force attack, that's true even for quantum computers (though the "drastic" increase is far less than for traditional computers, where brute force is O(N) in size of the key space, since for quantum computers Gr

          • A quantum computer doesn't need to use brute force, which is exactly the advantage given by quantum computing in the first place. Read about Grover's algorithm.
            • Forget what I said in my , I misread your post. But for RSA and other public key algorithms, the speedup is exponential, so they're effectively defeated by QC. Grover's algorithm is just a quadratic speedup, so it can be defeated by doubling the key size.
        • There are -way- more computational problems that we cannot (and will not) solve via quantum computers (or even computers that come after quantum computers). Just base the encryption scheme on one of those. ie: SAT will still be NP-Complete, even with quantum computers. Though if we -could- solve any sized SAT in an instant, we'd truly have godly powers over matter and energy (though by that time, security is unlikely to matter).

        • One time pad is still safe (Score:5, Insightful)

          by Maximum Prophet ( 716608 ) on Thursday September 27, 2007 @11:11AM (#20769829)
          The one time pad, where the key length = message length is still safe as long as you never reuse the key. (the "one time" in one time pad.

          As simple proof of this is that for any encrypted text of length N, there exists a key also of length N that will decrypt the etext to any plain text of length N. Therefore there is no way for an attacker to determine if an attempted key is valid or not. There if an attacker were to try every single key of length N, which is possible on some super large future quantum computer, all he will get out is every single decryption of length N, with no way to determine which is correct.

          Suppose the plain text was "attack at dawn" and the etext was "xbdhgfhwteriur". After the attacker used his q-computer he'd have "attack at dawn", "attach at noon" and "attack at fred", along with 64 quintillion other combinations.

          • The one time pad, where the key length = message length is still safe as long as you never reuse the key.

            The one time pad is always going to be secure, but it is of limited utility, since it requires a method of securely communicating at least as much information as you are trying to protect. There are certainly things that one-time pads are very good for, but there are lots of applications of encryption for which a one-time pad is never going to be a practical solution,

            • Just a nitpick. OTP key transmittion just needs to be tamperproof, not completely secure. i.e. You can send a courier with a briefcase full of keys handcuffed to his wrist and no key to the case. If the courier is accosted along the way, you just discard those keys, and send another batch. Imagine what kind of bandwidth you can get with a briefcase full of BluRay disks.

              • OTP key transmittion just needs to be tamperproof, not completely secure.


                Good point; the distinction is important.

          • Re: (Score:2)

            by glwtta ( 532858 )
            The one time pad, where the key length = message length is still safe as long as you never reuse the key.

            Provided that the pads you generate are truly random.
            • And truly one-time.
            • Absolutely. I've heard of several cases where folks have been caught reusing the pads. The Soviets were caught by the British when they started to reuse their pads after a year. Who would have thought that your attacker would keep data over a year and compare it with new data?

    • Re: (Score:2)

      by rjh ( 40933 )
      A complete answer to this question requires a solid (graduate-level) grounding in computational theory.

      However, I would point you to Lamport signatures [wikipedia.org] as an example of a digital signature algorithm which is secure even against quantum computation.

      Most symmetric algorithms are also secure against quantum computation. Using Grover's algorithm [wikipedia.org] we can reduce the total symmetric keyspace we have to search by an exponential factor of 0.5. This means that a 256-bit keyspace becomes equivalent to a 128-bit keysp

    • Re: (Score:2)

      by dintech ( 998802 )
      Modern DNA analysis has enabled the police to solve 'cold' cases recently. I would think this kind of technology would allow them to examine evidence in cases where forensics couldn't break encypted data. Think organised crime, peadophilia, data theft and so on. On the minus side, all you political dissidents should watch your back. :)
  • "What's a cubit?"

  • Sounds practical... (Score:2, Insightful)

    by indigest ( 974861 )
    ...until you read this:

    The whole apparatus was cooled to a few thousandths of a degree above absolute zero to make the circuits superconducting.
    Still stuck at square zero.
  • change the outcome of the story?

  • Yale group's press release (Score:3, Informative)

    by imakequbits ( 1163031 ) on Thursday September 27, 2007 @10:48AM (#20769481) Homepage
    Readers may find the Yale group's press release [yale.edu] interesting.
  • In other news, the NSA is partnering with NIST and University of Maryland to form the Joint Quantum Institute [nist.gov].
  • Does this remind anyone else of the short fiction story I don't know, Timmy, Being God is a Big Responsibility? [everything2.com]

Slashdot Top Deals

"The whole problem with the world is that fools and fanatics are always so certain of themselves, but wiser people so full of doubts." -- Bertrand Russell

Close