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Science

Stepping to Solid State Quantum Computing 108

Posted by Hemos from the baby-steps-to-omnipotence dept.
BetaBenj sent us the latest update from TechWeb concerning the latest advances in solid quantum computing. Recently, there have been a couple key advances bringing us closer-but we're still a ways out. Still, the ramifications of it are almost as staggering as nanotech. Almost.
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Stepping to Solid State Quantum Computing More

Stepping to Solid State Quantum Computing

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  • One of the most interesting things the article mentioned (I thought) was that the thing that "galvanized" research into quantum computing was a report that showed a quantum computer could break virtually any digital security system.

    Keeping that statement in mind, is it any wonder why people get excited about breaking into a secure computer system? Most mainstream people are appalled at crackers attempting to gain access to a secure system, yet here the same impulse is driving research that could fundamentally change our lives.

    I just always find it interesting when human nature morally cris-crosses itself....

    --Mid
  • Life spans keep getting longer. Why do you assume that you won't be alive in 100 years?

    Of course, remember the words of Scott Adams... "The average person alive today will experience 80 complaint-free years of life. Unfortunately, they will live to be 160." Or something like that.
    --
  • Given that "they" have discovered the technique needed to reverse aging (http://resolution.colorado.edu/~nakamut/telomere/ telomere.html), I figure we'll have an anti-aging agent within 20 years or so. It may be prohibitively expensive for many years, but it'll be available. (grey market?)
    --GAck
  • A good analog of the problem is the TechLine of the Laser. Hailed as the stepping stone to LightBasedCPU's [/:-)
    --
    First one Big as House--DeskTop--Hand--100/chip--"Now Optical Computers" nope.
    --
    The Feature Size of the Device, I/O and HouseKeeping are real Limits to any CPU.
    And once you have all this extra stuff keeping it from jamming the very effect you are using is not easy.

    Like CrystalMemory and others it works on paper only, Demo'ed as one shot, never seen again.

    my2c
  • The idea of a quantum computer, if I'm reading all this correctly, is to set up a set of particles in such a way that their wave functions will collapse into a configuration that corresponds to the answer to a given problem.

    How difficult is it to do this setup?

    Given that the experiments I've heard of are on the 2+2=4 level, how do we know that the difficulty of setting up a quantum computer to factor a specific 1024-bit number isn't comparable to the difficulty of doing the factoring by deterministic algorithms?
    /.

  • This is a two-parter:

    First, to Sangui5:

    Sure, there won't be many of these built for a while, and sure, only governments might be able to afford them. But remember, it isn't just a few people with PGP that rely on RSA. Banks do. Government agencies do. Other governments do. I personally don't want some revolutionary nut in a third-world country stealing a quantum comp. and raiding my bank account. I'm funny that way.

    To the Anonymous Coward who suggested quantum encryption:

    Oh boy, there's some fun: first, you have to build your own communication medium, because phone lines and satellites are out. It has to be strong, it has to be extremely accurate, and it has to be completely isolated. Oh, and you'll need to make many different versions. And they all have to be hard-wired, as you can't do this sort of thing over radio waves. I'll explain why at the end. Second, you have to know what the error rates of the particles you're sending actually are. Counting photons is a tedious job. Third, you have to find someone else with the same setup you've got.

    So you finally got your quantum encryption set up. Now what? Well, here's where it gets funny: quantum "encryption" is as effective if you are using 256-bit RSA encryption or if you are using the secret code from the ring you found in your Cracker Jack box. Why? Encryption is based on the concept that you don't want anyone to whom you don't give permission to see your data. All quantum encryption does is change the medium so that one of those pesky laws of quantum physics, Heisenberg's cute "uncertainty principle", keeps other people from looking at your stuff when it's in transmission without you knowing. You will know someone's watching because the error rates have risen. Oh, and to keep this medium working, it has to be as isolated from natural interference as possible. So, what happens when you know that someone's reading your stuff? You have to change channels, so to speak, and use a different connection, or wait until that eavesdropper gets off your communication line. Sounds annoying, doesn't it? Well, it is, as well as financially unfeasible for, say, an entire country.

    So, which is worse, the problem or the solution?


    Mike
  • Example: searching a list of items for a value on von Neumann machine is O(n) (length of the list), since you have to look at each element till you find the one you want. You can do this in O(1) on a parallel machine. This is a significant improvement. IIRC there was a quantum computer that could search a 4-element list in O(1)


    Assuming that you have a constant number of processors in your "parallel machine" searching through an n-element list still takes linear (IOW, O(n)) time. This is pretty obvious to see since your uniprocessor machine can emulate a k-processor box where each virtual processor runs at 1/k (minus context switching overhead) the speed of the original processor.

    Also, you don't need a special computational model to search through a 4-element list in O(1). In fact, I have an ultra-secret algorithm for searching through a 5 bazillion-element list in O(1) on a Turing machine!!! (hint -- if the size of your input is constant and the function is computable, you'll always be able to compute the answer in a constant amount of time).


    -NooM
  • I find it fascinating that /. readers are so often scientific illiterate in so many fields, including computing. (Yes, this is a flame directed at almost everyone; moderate away...)

    In this case, I refer to the belief that 'all computing is equal', that the only difference between, say, a QC, a Compaq and my brain is in the implementation and speed. QC's are not just really fast, expensive and fragile supercomputers, they won't run Quake or Linux, and they won't replace those anyones Compaq. They do a few things really well--sorts, searches, etc--but most things very poorly, if at all. They are less general purpose machines than accessories, designed to fulfill some specific needs--coprocessors for your Cray, rather then replacements. On top of that, they cost a fortune and are unimaginably fragile compared to a desktop machine.

    In some fields they will be revolutionary, but for the most part the effects will be similar to the release of the K7 on the population of Iran.
  • Given how much computational power is stuffed into the three pounds or so of grey matter I have in my head, a figure I expect to be quite large as I wouldn't be surprised at all if my (or anyone else's) brain had more power than every computer on the planet combined, I expect that the brain *already* does QC on quite a large scale.
  • I did some reasearch on this for my degree a couple of years ago. I got most of my info from the los-alamos pre-print archive under quant-ph.
    http://xxx.lanl.gov/archive/quant-ph [lanl.gov]
    Some useful background information is in Andrew Steane's paper [lanl.gov], but you will get heaps more stuff with a quick search.

    Remember this site: http://xxx.lanl.gov [lanl.gov] it's damn useful.
  • Can anyone point me to a decide 'for dummies' quide to QP on the Web? This stuff fascinates me, but I have only a rudimentary background in Physics, so I'd like to see the whole thing explained in 'layman's terms' (in as much as it is possible to explain it at all!!)
  • From what I understand about the NSA, "National Security" is paramount. Most of what I know is from reading "The Puzzle Palace", and he pretty much posits that NSA is *ALWAYS* a minimum 15 yrs ahead on tech, and usually 2 to 3 levels of tech above anything that we see. Assuming that, the fact that this is in the private sector leads me to believe that they're (NSA) on to bigger and better things. What that might be, I have no idea. Probably something odd discovered in the search for M/string-theory.

    The CMPNet article scares me because they are talking practicality. Not 20 years off. Real world, many-bit devices. And NEC, the one with the solid state research, is a multinational corporation. Lucent, I hear is also in the game -- nearing practical results. I can't remember my source on the Lucent stuff, so take it with a grain of salt.

    ratatatat
  • Posted by Faithless the Wonder Boy:

    If we were to make games completely real, they'd lose a lot of the fun. For instance, the rocket jump would simply send bits of player flying all over the arena. A one-hour deathmatch would result in all the players getting exhausted, and a couple of them dying from heart attacks. Also, control mechanisms would have to become much more advanced, giving you control of breathing, more exact control of limbs, etc. Such a system might be good for a simulation game such as 'Hidden and Dangerous', but it would lack the immediacy of Quake.
    --------------------------------------
  • Posted by Lord Kano-The Gangster Of Love:

    Making more immersive games (IMO) would relieve lots of stress. After all, why blow away all of your classmates when you can pretend to and not have to go to jail after?

    LK
  • Well just looking at another view of this, talking about the bone breaking and blood loss ect. One could gather that this could use quite well in the medical research feild.


    You miss my point - QC might *not* do this any better than standard computers.

  • That's what I said: all computers aren't equal. In fact, that was the *whole* *point* of my post! (Not reading posts before responding is my second complaint about /. 'readers', but is rapidly moving up to #1.)

    QC's aren't Turing machines, and apparently neither are brains (I'm currently studying the latter). However, I don't believe that QC's are more powerful than Turing machines. They are certainly faster in some ways, but the range of functions they can compute is quite small, and AFAIK they cannot compute anything beyond the capabilities of a Turing machine (given enough time). This would make them more of an optimized sub-Turing machine.

    As far as what *is* more powerful than a Turing machine, most of the candidates are actually variations of TM's (oracles, etc), or analog (such as recurrent neural networks) systems. I don't believe QM has much to offer here, unless it can add a new realm to the analog-digital spectrum.

    And for the record, I've never taken any CompSci courses, though I sometimes wander through the field chasing a neural network.
  • And if the attacker has access to the physical channel (which he must to get the info) and he has a quantum computer then he could almost certainly just intercept the entire signal and reproduce it, so he gets the info he wants and the reciever has no idea it was intercepted. The error rates would be lower due to the decreased distance from signal source to reciever and therefore the reciever might find out, but this could easily be overcome by purposely introducing error into the signal he sends as he sends it.
  • >...but they're worthless for transmitting
    information so in practice relativity still works.

    This is exactly what may not be true if Bohm's theory accurately accounts for quantum phenomena..

    At least, that's what I think David Z. Albert was saying in class...
  • Yep, this extraordinary new technological possibility does not thrill me, it scares me. Not because I think of nefarious uses, but because I know that I don't have the desire to go back and really learn to use Hamiltonians that I haven't seen since Advanced Engineering Math. I also don't want to brush up on the quantum physics that I never truly understood to begin with.

    There was a day (year/decade), when the idea of learning new things and facing new challenges thrilled me. Now I'm just glad that I have saved enough money to retire comfortably.

    I'm old and I haven't even turned forty yet. I can't scoff at all those old used-up professors any more; I am one.
  • um, sounds quite a bit like real life, eh? Hopefully someone can steer me in the right direction here, but it seems to me when we can figure out how to do large scale quantum computing we'll be basically able to do anything. Aren't the "Universe as we know it" and that pen on your desk just part of a big (very) quantum computer? Aren't we?


    I think the final straw is Heisenberg's theory, it'll be tough to get around that one. And, of course, the fact that time keeps going.

    (is this what happens when geeks go meta-physical?)
  • Wasn't that also true of normal electronic computers for many years? Eventually, they ended up on everybody's desk.

    Just give it time.

  • Ahhhh, super-fluid helium! All of those days studying frictionless surfaces in physics won't come to waste if I ever get my hands on some SF helium.
    Imagine having a play toy at tempuratures under 7K. Or in the case of the article 1K!

    Unfortunately with the fact being that one needs temperatures that low in order to have the right conditions for quantum computing means that we probably won't see a consumer version in our life time.
    The amount of really cool stuff that can be done at temperatures 1K and lower is amazing. Eistein-Bose condensates, which lead to matter beams, which lead to true 3D holograms like what we have seen in so many movies. Quantum computing. Tests with frictionless surfaces. Ahh. That is why I'm a physics major.
  • "Thus far, no quantum computer using a solid-state..."

    Not gonna Happen Folks. QC is dead end.
    Basic Problem is the cross talk issue in packing.
    They have solve that one first.

    my2c
  • One of the most interesting things the article mentioned (I thought) was that the thing that "galvanized" research into quantum computing was a report that showed a quantum computer could break virtually any digital security system. Keeping that statement in mind, is it any wonder why people get excited about breaking into a secure computer system? Most mainstream people are appalled at crackers attempting to gain access to a secure system, yet here the same impulse is driving research that could fundamentally change our lives.

    There is a big difference between exploration and conquest. Remember that technology is amoral, it is the applications/outcomes which are determined by our positive or negative tendencies, and even that is defined to some extend by social context. The psychology of "crackers" (essentially ego driven) is completely different from the pure form of hacking (curiosity driven), about the same difference between a vandal and an artist. Both might use similar techniques but the creative tendencies of an artist are channeled into positive outcomes.

    Researchers are a different breed from paranoid security cryptoanalysis (at least I hope so as my taxes are being levied for them to be paranoid). Science and research operate in a climate of open and free exchange of ideas and anything which is regarded as a "difficult challenge" is of interest. Security on the other hand is dealing with control and exclusion (private property) which tends to bring out the acquisitive side of human nature (remember wanting a toy just so that your sibling can't have it?). The impulses that drive research and finding knowledge (and to some extent pure hacking) are not the same as cracking and destorying data.

    I just always find it interesting when human nature morally cris-crosses itself....

    Society has developed informal rules (social norms) and institutions (courts, non-profits) to minimise human nature to destroy itself. Morality is a rather complex abstraction in its own right. As one wit once noted on the dispartity of income distribution along the age axis

    "If you're not a communist when you're young, you've no heart. If you're not a capitalist when you're old, you've no brain"

    Good, bad, indifferent, we are all evolving bitstreams in the global memory of human conciousness. I only hope that people have enough self-awareness of their own nature and act accordingly.

    LL

  • First, we do not believe that quantum computers could solve NP problems (QP != NP in CS speak). If I remember correctly QP is strictly contained in #P (really P^#P). This means that a public key cryptosystem based on NP complete problems instead of factoring numbers could be secure against a quantum computer.. except that many many cases of an NP complete problem are easy to solve.. but if we can't use factoring numbers because of the preasence of quantum computers then this might be an acceptable alternative.. it could mean you would need to upgrade you're key (and software to generate keys) frequently to keep up with advances in mathematics and CS.

    I geus a cheezy way to describe the limitations of cuantum computing is to say that you get a lot of really powerfull parallelism, but since you only read out one answer you can not directly take advantage of it. The quantum algorithms ``make the wrong answers cancel out.'' Currently all the quantum mechanical algorithms which provide exponential speedup (like factoring) work by finding the period of some function by useing a Foruer transform.

  • Yeah you're right... (Score:1)

    by Anonymous Coward
    there will be a market for only about five quantum computers.
  • It may well be that Quantum Computing will open up new ways of encrypting, but I can't see them. Everything I know encryption leaves me to believe that we are wide open. What little that I understand about the quantum microverse and quantum computing, leads me to think that anything quantum can *do*, it can *undo*. Although you may be able to encrypt huge keys, quantum allows you to try ALL the combinations on the lock at once, no matter how large. I know that practicality means you have to carve the key up so that you can go at it with the number of bit's you have at your disposal, but I don't see that as much of a barrier.

    ratatatat
  • That's part of quantum electrodynamics IIRC (I'm not a physicist, nor do I play one on TV). In a sense it's not all that "deep": any QED interaction is indistinguishable from an interaction where all particles are replaced by their antiparticles, viewed in reverse. So antiparticles are essentially the same as normal particles moving backward in time from the standpoint of QED.
  • No.

    No, No, No.

    NP-complete problems are hard.

    All of them.

    Equally hard.

    That is, if you can solve one NP-complete problem, you can use it to do the others in polynomial type. A Hamiltonian oracle can solve 3-coloring, circuit-sat, traveling salesmen, and the others, fast

    ...

    I don't really know if quantum computers can solve NP problems, or even factoring for that matter, since I don't know how to phrase algos in quantum computable terms....although, like parallel algorithms, it'll be a booming area of research, you can bet.
  • we only use about %10 of our brain though. a computer running a good os can utilize allot more of what it's got.
    and the os can always be updated with greater ease. i guess the problem is that most people never need more that %10.
    imagine using a chip in your brain to focus cerebral development to the field of your choice.
    then again, having a powerful unit for processing hooked up to your motherboard (brain) means little if you can interact with it
    at great speeds.
    once again we're limited by our inferior architecture.
  • Posted by Lord Kano-The Gangster Of Love:

    Rendering aside, this type of computer could consider more variables in a game than anything that is currently available. Back to the FPS game.

    Let's just list a few factors which would influence the outcome of a match.

    Height
    Physical Condition
    Heart Rate
    Rate of Respiration
    Lung Capacity
    Age and related degeration of bodily systems
    Type of footwear
    Striations of the barrel of a firearm
    Irregularities in the surface of a bullet
    Wind Resistance
    Crosswind
    Temperature
    If clothing fibers would clog a hollow point to such a degree that it won't expand
    Finger Length
    How a weapon performs as it heats up and the moving parts wear

    Even if rendering routines for quantum computers are never written, it is the underlying computations that make the sim important, calculating voluminous numbers of possibilities is where the strength of quantum computing lies.

    For example, quantum computers could determine exactly what is a perfect game of chess.

    Rendering is the easy part, that can be handled by hardware that is only a few years away on our current path.

    LK

  • Actually, the consensus among complexity theorists is that quantum turing machines are more powerful, even theoretically, than regular probabilistic turing machines. This has not been proven, for similar reasons that ~(P=NP) has not been proven either (namely, that it is freakin HARD problem to do so).

    For more on this, look at this paper by Umesh Vazirani (one of the big names in computational complexity): Quantum Complexity Theory [berkeley.edu].

  • I believe he meant that in many cases, a "random" instance of an NP-complete problem will be relatively easy to solve. As an example, most instances of satisfiability tend to be very simple for any reasonable search procedure. This leads to the occasional newby claim of: "I've proved P=NP! See how fast my program is on these random formulas with 1000 variables!" Getting a hard instance, as required in cryptography applications, requires that you pick very carefully.
  • >This is getting quite repetitive.

    'Twas meant to be a joke -- the "OW!" was meant to be my response to someone smacking me upside the head for saying this...

  • Open Qubit (Score:3)

    by photek ( 66911 ) on Wednesday July 07, 1999 @07:36AM (#1814946) Homepage
    Now that the theoretical is no longer so difficult to achieve physically, maybe we can focus more on the practical uses of QC. Check out openqubit.org, they are currently working on QC models, ways to implement Shor's algorithm, and other interesting things.
  • Sounds great! Does anyone else see the death of e-commerce in this?! I never did care much that the NSA probably had this stuff long ago, since I'm not a national security risk (at least I don't think I am). But large corporations having this stuff bothers me. Nothing was secure from the NSA (if you thought RSA wasn't crackable by them...dream on), but having nothing secure from corporations is a whole other problem.

    And wait until some hacker cracks into Lucent's Quantum Computing Array, and breaks into your bank account.
  • Posted by Lord Kano-The Gangster Of Love:

    This presents excellent possibilities. Imagine a distributed.net client, or a game executed on such a machine.

    The realism or flight sims and FPS games would be mind boggling. A machine like this would be able to calculate whether a bullet would glance off of a rib and break it or if it would punch straight through. How much blood would be lost, and friction could be calculated to determine how much one would slip on the blood.

    This is very cool.

    LK
  • Reading this article, I can't help but thinking of Konrad Zuse working in his parents apartment, building a -mechanical- memory system for his computers back in the 30s. Yikes. Sure, it was a binary system, but it was a far cry from modern computers.

    Quantum computing is at much the same stage right now. Some brainy-folk have shown that the math works, and it should be possible to build these things, but now we need to invent ways of making it practical.

    The only thing that worries me is that I'm going to need to learn how this stuff works some day if I want to keep a job in the industry!


  • Great. We will shortly (20 yrs?) have quantum computers. But is this a good thing.

    Yeah, it would be great for all sorts of things (just imagine the speed boost for things like ray-tracing, searching, and sorting) but it would also make a brute force attack on any encryption algorithm a simple matter, rather than a computational nightmare.

    Now, it would be fair if everybody had their nondeterministic turing machines to chug out quantum encryption, but how much is this going to cost. I'm thinking that quantum computing, and all of it's benefits, will be the realm of governments and large corperations, at the expense of everybody else.
  • A more realistic Quake? That would be awesome. And the effects on an X-Wing vs. TIE Fighter style game...whoah. That game was cool enough. If this allowed it to become more like the movies...Sign me up!
  • "Thus, in contrast to a conventional computer, quantum registers can perform single operations on combinatorial sets of data, making them far more powerful."

    This sounds pretty rad. I used to read all kinds of stuff about quantum physics, and Niels Bohr is one of my heros, I'm glad stuff like this is finding some real practical applications.
  • Well, couldn't you in theory also use the
    quantum computers to come up with mega-bit
    encryption keys? The whole point of RSA is that
    it's much easier to encrypt than decrypt- when
    processing power means you can decrpypt something, it also means you can encrypt it another order
    of magnitude up..

    (Not very technical, I know, but the point is that
    there could be new forms of encryption also
    based on quantum computers)
  • >>The only thing that worries me is that I'm going
    >>to need to learn how this stuff works some day
    >>if I want to keep a job in the industry!

    Yeah, but remember back 10-20 years ago when
    people thought the same thing about PC's.
    Now they're (basically) easy enough for
    everyone to use! I'd love to learn about them,
    but just to know. I'm not a prgrammer, I just
    think the possibilites are way cool!
    -------------------------------------

  • I have a friend who was working on the open qubit project - they've opensourced their work, but there seems to be a shortage of quantum physicists that know C. :)

    Anyway, more interesting is the prospect of encryption with qubits using "intertwining" of particles to ensure that nobody can listen in on your conversation.. without you knowing about it. Think about it. If somebody "cracks" your encryption scheme, you know *right now*. That would basically eliminate alot of signals intelligence that the NSA engages in today. They won't be getting much funding from uncle sam, I can assure you of that!



    --

  • An explanation of quantum computing?? (Score:1)

    by Anonymous Coward
    Thus, in contrast to a conventional computer, quantum registers can perform single operations on combinatorial sets of data, making them far more powerful.

    Can anyone try and explain this a little more clearly? I took a half a semester or so of quantum mechanics in college, so I'm familiar with superpositioning of quantum states, Schroedinger, and such, but I'm still confused as to how that can be used to allow for operations to be performed on combinatorial sets of data... I'm looking for an answer more from a computer science standpoint rather than a physics one, if it's possible...

    Dave

  • You might note that you posted to the wrong article... but as a side issue:

    With quantum computing does that mean we could only view the contents of a Micros~1 Word document or modify them but not both?

  • Re:So, what will be next? (Score:1)

    by Anonymous Coward
    Information still can't be transmitted faster
    than the speed of light. Quantum entanglement
    effects (such as a pair of photons having
    instantaneous effects on each other irregardless
    of distance) can seem to violate the speed of
    light, but they're worthless for transmitting
    information so in practice relativity still works.

    Quantum entanglement can be used to provide
    quantum cryptography over networks - unbreakable
    codes, even with a quantum computer.
  • Of course there's such a thing as a degree Kelvin. It's equal to degrees Celsius, only measured from the hypothetical absolute zero instead of the freezing point of water at standard pressure.

    Still, you were probably thinking of something specific when you said the above. What was it?

    gomi
    incomplete statements cause such trouble
  • "And I predict that in 10 years time, computers will be 5x more powerful and 100x larger, and so expensive that only the 5 richest kings of Europe will own one."

    - That geek guy from the Simpsons in the episode where Abu gets his US citizenship.
  • You are right that the final straw is Heisenberg's theory. By observing, or computing in this case, what will happen will by the most basic law of the universe change that result so that it may not. That is the beauty of the quantum world. This is one of those cases where you can't fight fire with fire.
    Predicting large objects, by large I mean things large enough that classical mechanical physics can be used without too much degredation in accurace, will be easily computed. When you get down to the quantum level of physics, by the time the quantum computer knows the answer it will have already have happened because one is still just dealing with probabilities at that level.

    As for time only going forward. Read Feinmann (I know I misspelled his name). He had devolped this really interesting and far reaching theory about the idea of anti-matter actually being matter going backwards in time. Mathematically all the speed of light is is a vertical asymptote. It slopes up then comes right back down. :)
  • Yup, and in a couple of years I will have my own Eistein-Bose condensate as a pet living in my house.
    There is a difference, electronic parts can be easily manufactured. Apparati that can get temperatures of 1K and lower won't be for a very very long time. Also, there are enough problems with people hurting themselves on computer today. Imagine what would happen when one of these breaks open and freezes some poor bastard into an icicle. His wife comes home, screams, and sues. Tempuratures of 1K are NOT SAFE!
  • I love my major. Gives me the practical education of an engineer with all the scientific background of a physics major.

    As for practical applications, look at Eistein-Bose condensates and matter lasers. :)
  • The idea would be to add the QC systems to a general purpose processor.. like say, an x86.. hey, they have a whole load of instructions no-one uses now.. why not add superstate registers and quantum add instructions.

  • Oh boy, there's some fun: first, you have to build your own communication medium, because phone lines and satellites are out. It has to be strong, it has to be extremely accurate, and it has to be completely isolated. Oh, and you'll need to make many different versions. And they all have to be hard-wired, as you can't do this sort of thing over radio waves.

    Packet-switched networks are out too (I think?).

    :(

  • What little that I understand about the quantum microverse and quantum computing, leads me to think that anything quantum can *do*, it can *undo*. Although you may be able to encrypt huge keys, quantum allows you to try ALL the combinations on the lock at once, no matter how large.

    I don't know much about quantum computing either, but from what I've read in the context of cryptography, quantum computers are able to solve many (most? all?) problems using the square root of the number of operations needed by conventional computers.

    This would make a 128-bit key solvable in 2^64 operations. You would need a 256-bit key to have the same security as a 128-bit key seems to offer today.

    Quantum computers will not be able to test every possibility simultaneously. I don't recall details, but I think it had something to do with getting only a certain amount of information about the answer out of each measurement.

  • Um... A more realistic Quake would be /boring/.

    One shot clips the side of your knee, and you collapse in a screaming heap, and remain there bleeding to death for the rest of the game, unless someone puts you out of your misery...

    Fun.

  • With quantum computing does that mean we could only view the contents of a Micros~1 Word document or modify them but not both?

    No. It means that you can not view it without changing it. ;)

  • I wonder what extent the NSA would truly go to hide this kind of technology (assuming they have it) from the rest of the world. Yes, the NSA wants to be ahead of everyone else, but the value of this kind of technology in research would make the importance of National Security pale in comparison. The devlopments that could be made in gene research alone seems to me like it would justify the sharing of the technology, at least among secure research facilities. So quite simply, in addition to it being unlikely that the NSA is *so* many years ahead of us, I think some of the many scientists who work at the NSA would be likely to have given at least a hint that quantum computers exist. As too your main concern, yes, quantum computers in the hands of crakers could wreck havoc on security in e-commerce, but honestly, even many years after this technology is feasable, it will be confined to research environments such as universities. It won't be available to corporations for a VERY long time, and more secure methods for e-transactions will evolve as machines evolve. As for the desktop, I don't expect my children 20 years from now to be playing Quake XV on a quantum computer. Its a neat and promising technology, but a long way off, last I heard there was still a good 12 years of Moore's law growth in standard silicon Turing Machine based chips, and expect that to grow at least a little, as other developments are made. Still I can't wait to see what comes next!

    Spyky
  • But part of my point is that nobody other than governments will be able to afford this for a long while.
  • The realism or flight sims and FPS games would be mind boggling. A machine like this would be able to calculate whether a bullet would glance off of a rib and break it or if it would punch straight through. How much blood would be lost, and friction could be calculated to determine how much one would slip on the blood.


    I'm not sure about that. The current applications that are being proposed for QC are of a fundamentally different nature. QC speeds up things like searches, but I can't see a way for it to easily speed up things like rendering or kinetics simulations. At the very least, a very different approach to those problems would have to be thought of.


    Does anyone else have more information on what kinds of problems quantum computing will and will _not_ be good at?

  • I don't pretend to understand (Score:4)

    by aheitner ( 3273 ) on Wednesday July 07, 1999 @08:53AM (#1814986)
    the technical details described in the article, but I do have (imho ;) a decent understanding of the computational principle behind quantum computing. I've seen some pretty wrong (or just confused) things in the comments...and /. discussions of encryption/complexity related issues frequently get mired in BS ;)

    Quantum computers do not really translate to higher FPS in Quake3 or more realistic flightsims. You don't get quantum computers that have amazing SPECfp numbers.

    Quantum computers do operations that normally take one order of magnitude in a much lower order time. Example: searching a list of items for a value on von Neumann machine is O(n) (length of the list), since you have to look at each element till you find the one you want. You can do this in O(1) on a parallel machine. This is a significant improvement. IIRC there was a quantum computer that could search a 4-element list in O(1).

    Obviously, that's a pretty trivial problem. Even for very long lists, O(n) isn't bad, and you can do it in parallel.

    What about fundamentally much more complex problems, such as factoring, or better, something NP-complete such as circuit-sat or Hamilton paths (that's what the article was talking about, I think. Those guys think their quantum computer is a Hamilton oracle, if I'm right. So you have to pose questions in the form of graphs...not a serious problem since all NP is orthogonal). A parallel machine doesn't help there. But a quantum computer can take NP problems from exponential to polynomial time.

    All of a sudden factoring (not NP, just decently hard) goes from taking 100 trillion years to taking hours.

    Yes, all encryption that uses factoring as a trapdoor (one-way function) would be toast.

    No, it wouldn't necessarily be any better at running first person shooters.

    Still, an NP oracle machine IMHO would be much more significant than some bloody nanotech robots.
  • ... the Bell Labs-Michigan State University proposal uses electrons floating on a liquid-helium surface inside a vacuum chamber.
    Hey, you could put an eye out that way!

    So, when does Sun put Java on this thing? When does Microsoft announce "Visual Q"? And, of course, you'll need a larger quantum computer to run that one, and it won't be compatible with other quantum programming languages. But an animated quark will pop up from time to time and advise you on your programming style.

    I read an article in Sci-Am about this quantum superposition stuff. And I still don't understand how I would go about using it for computation. I feel like such a caveman.

  • Tell me more about this "open qubit" project!

    One method of quantum encryption (the one I've studied) is not really encryption at all. Alice sends Bob messages in plaintext, as individual quantum states. Now, if Eve wants to intercept that signal, she must measure the quantum states as they go by; that measurement will necessarily corrupt the signal, and Bob gets a meCsaTe with a f3w bits scraBbled. That's a signal that Eve has been mucking around again -- but better yet, if the message is NOT scrambled, Bob knows that NOBODY could have been snooping; and if the message is scrambled, Bob knows by how much is scrambled how precisely Eve has snooped.

    Several drawbacks to this method: you have to be able to measure individual quantum states (which means expensive equipment); you have to have a network that doesn't lose much of the information in the fragile quantum states (or at least loses a definite, known amount of information). That means you probably can only use it over a local network, at least with current (read: "at least 10 years ahead") technology. (You also have to know the expected information content in the message to determine that something's been screwed up, but that's usually easy.)

    Another method involves using EPR pairs to "teleport" a message by measuring one of the pair (which causes the other to collapse based on the choice of measurement) -- you need to send a classical message with the signal (so speed-of-light won't be violated with this method), but the classical message is meaningless without the EPR state, and vice-versa. Again, good luck carrying around your very own EPR pairs; hope you have a huge budget!

    --

  • No one has suggested how awesome a Beowulf cluster of these would be...OW!
  • I'm an engineer, not a physicist, so I don't completely understand quantum mechanics, but from an engineering standpoint it makes sense.

    In a combinatorial set of data, operations are order independent. Because of this, you can configure the quantum hardware in such a way that all of the appropriate electron jumps can happen in one clock cycle, since thousands of electron jumps can happen in less time than we can clock (we're talking femtoseconds here).

    Only when operations are order dependent (1 + 2 * 3) must we be sure one thing has completed before we begin another, and this is the reason we use clock cycles. For (1 * 2 * 3 / 4) order doesn't matter.

    Each operation takes a certain amount of time to complete (due to propagation delays, gate time, etc). You can't hit the next clock cycle until results have stabalized. Right now we are working to make conventional gates faster so that we can drive clocks at a higer rate. Imagine a single gate system that could do thousands of order independent operations at the "same time" (one clock cycle). So this "single operation" is really many many multiplications and divisions, but it can happen in one clock cycle.

    Make sense?
    It doesn't to me :)
    -Alison
  • Yeah, game realism would be incredible. But imagine what we could do if QC-ing was integrated into our brain! We'd be god like, in that processing information would go far beyond our current (pathetic) rate.

    EVERYTHING would change, new challenges and new goals would replace the old ones.

    Forget game realism, the focus would shift to mathematical computing for fun.

    "Perfection is achieved only at the point of collapse."


  • This is completely theoretical, and I am using approximates for several figures -- but you'll get the general idea.

    Say a "supercomputer" (from the article) is equivalent to a 10,000 MHz machine. This would make our neat new "chip" the equivalent of a 8.76e15 MHz processor. Wow.

    Going to distributed.net and looking up the current stats for the RC5-64 project (http://tally.distributed.net/rc5-64/), I saw that it had done 27,504,975 blocks yesterday with 41,655 machines contributing. Let's say, on average, 30,000 machines contributed for the full 24 hours (some people may turn theirs off, etc.). Let's also say that the average computer is the equivalent to a 300 MHz machine, which gives us a combined 9,000,000 Mhz per day.

    At 27,504,975 blocks per day, it would take approximately 2,499 days to go though all of the blocks. However, if we substituted our 8.76 quadrillion MHz processor in, we could do 2.677e16 blocks per day. Not too shabby. At that rate, we could have done all of the RC5-64 blocks in 2.57e-6 days, which is 0.22 seconds.
  • I had a physics teacher in high school who insisted that it was called -273.15 degrees Celsius but zero Kelvin (i.e., no "degree").

    I had some physics courses too at university, but I don't remember what they called it there.
  • Posted by ebenjamin:

    Using embeded Quantum Computers to control your nanomachines is it!!!!
  • This presents excellent possibilities. Imagine a distributed.net client, or a game executed on such a machine.

    Unfortunately I don't believe that these computers will be any better to these types of problems than regular computers. Although quantum computers are several orders of magnitude faster than regular computers for factoring and similar problems, I haven't seen any algorithms that let them say render a scene.

    In some sense quantum computing attacks a fundamentally different problem then regular computers and using quantum computers to solve problems that regular computers do well may be just as inefficient as using regular computers to factor large numbers.

  • I'm a big Feynman fan, read some books and watched some specials, a truly unique geek. Does anybody have a link about...
    He had devolped this really interesting and far reaching theory about the idea of anti-matter actually being matter going backwards in time. Mathematically all the speed of light is is a vertical asymptote. It slopes up then comes right back down. :)

    I did some quick searches, but couldn't find it.
    I love this stuff and have written a few papers on it, relating quantum physics to the meaning of life and all that. It'll be up soon, stay tuned....


  • What is the "cross talk issue in packing"

    Could you elaborate a bit?

    thanks,

  • Don't understate the power of the quantum logic gate. The quantum computer isn't merely moving around the processors so all of the jumps happen in the same cycle. A quantum computer uses a fundamentally different logic gate. In essence, the 1 and the 0 are both registered at the same time because what's being registered is not the particle, but the probability of where the particle might go. The probabilities are what are manipulated by the hardware, and where the electrons actually go determines the answer. This is as simple as it gets. However, I know that this probably doesn't make much sense to a lot of people. (It only makes some sense to me because I had to write a report on quant. computation&cryptography and neg. probability.) My advice to anyone who is not extremely well-versed in both computer science and quantum mechanics (there are like a dozen of them on the planet) is to find a book on the subject. I'd recommend G.L. Milburn's "The Feynman Processor" (he's one of those dozen).

    That's just my two cents though.

    Mike
  • This is getting quite repetitive.

    How about every time a new kind of computer is mentioned on Slashdot, we take it as a given that a Beowulf cluster of them would be cool? Then moderators can mark posts like this as "Redundant" and everyone saves a little bandwidth.
    --
  • The inception of full-on Quantum Computers will no doubt be a major milestone in the tech age. The benefits are countless. However, will Quantum Computers mark a pinnacle? What's next? What could be faster?

    Certainly, with this technology, we are nearing the threshold of "smaller, better, faster", no?

    Hermm...

    -Cereb
  • any more info on icaveo??? went to the site and checked it out; whats up with it? they claim they are using starbridge + proprietary algorithms to search code, video, audio, text..
  • When will we start to hear about Quantum Networking?

    I'm no expert on QM, and I believe that this particular aspect of the subject is controversial, but as I understand it, a plausible interpretation of Bohm's theory allows for the possibility of transmitting a readable signal to any point in the universe, instantly. That would sure beat the hell out of Gbit ethernet, and even that terabit line Siemens is working with... basically, anything that operated with light or electricity would be toast..

    Open fire if you think this is way off base... given how much I know, you're probably right.

    Anyway, just a random thought..
  • I would prob use it for SETI instead.

    But then again having my own holideck *sp?* aka Star Trek would be nice :)
  • Unfortunately openqubit.org [openqubit.org] is nothing but a "coming soon" sign. :( While we're waiting for that to open up we can go to www.qubit.org [qubit.org], particularily the "Introductions & Tutorials" [qubit.org] page.

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