Quantum Computers 61
joecool12321 writes: "Although Richard Feynman spoke about quantum computers in 1981, technology is only now starting to catch up. This article at Scientific American discusses recent developments towards the goal of 'infinite computing,' and research is showing that scalibility may not be far away, and thus scalable qbits."
Re:A Question... (Score:1)
You're both right (Score:1)
But I, like you and previous poster, think he's out a limb (if not out of his tree completely).
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Non-meta-modded "Overrated" mods are killing Slashdot
It's not (Score:1)
You know the difference between DFA's and NFA's right? An NFA is like a "parallel processing DFA" (speaking loosely). So here's the analogy: NFA:DFA::QuantumComputer:TuringMachine.
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Non-meta-modded "Overrated" mods are killing Slashdot
Finally, (Score:2)
A reliable /dev/random! /dev/null that can hook up to a USB port, everything would be fine.
Now if only I could get a
It is a good day to die. (Score:1)
You know things are getting cool when components of a computer start getting named after scientists (remember the Heisenberg Compensator [startrek.com]?)
Re:Finally, (Score:3)
Re:The true effects of quantum computers (Score:3)
Actually let me clarify a bit of this. First of all an example of what it means to be reversible. The best example of this is that you can't clear memory / registers. Setting something to zero is a destructive, non-reversible process. Basically any "program" run on a quantum computer would be runnable backwards and using the all the outputs you could find all the inputs. Even a simple program like C = A | B would have to keep another bit of data, a "D" that would enable you to reconstruct A and B using C.
Now the types of things that quantum computers would in theory do really well take advantage of being able to use an input state that is a superposition of all possible inputs. The prime example is factoring huge numbers. The number to be factored is entered as one input to the process, and the second input to the process is a superposition of every number from zero to the number to be factored.
The quantum computer then divides the number to be factored by this input vector, and retains the remainder, which is a superposition of all possible remainders from that division.
Now there will be patterns in the remainders from the division, and if you take a fourier transform of those remainders you will get big peaks that correspond to the factors.
At this point your calculation is done so you measure the output. Remember that everything that has happened so far has been happening internally to the "quantum computer" and has not been observed. Your observation of the output collapses the probability and you get one output point, but if you repeat this operation a hundred times or so, most of your output points will be somewhere in this peak.
The cool thing about this process is that it takes advantage of the fact that you can do a fourier transform in the intermediate step before you collapse the probability. To get enough points to do a Fourier Transform in the intermediate state in a traditional computer you'd need to get thousands input vectors, but the quantum computer only needs one.
(btw, IANLAPBITEPIS (I am no longer a physicist but I took engineering physics in school), so if I messed up somewhere here and someone can correct me please do)
Re:Quantum computers and Moore's law (Score:2)
Re:It is a good day to die. (Score:1)
Two Edge Sword that favors the Powerful (Score:1)
Re:You're both right (Score:2)
Re:The end of encryption? (Score:1)
Actually, even a quantum computer cannot break (within reasonable time) the newest block ciphers. AES is specified with 128, 192, or 256 bit key. Why up to 256 bits, when 128 will withstand any concievable brute force attempt for at least the next thousand years or so?
Because a QC can only do so much better than a regular computer. In this case, the square root of the effort by a normal computer. That's a 2**64, 2**96, or 2**128 effort, even with a full QC. So even a quatum computer (or a million million million of them) cannot brute force a 256 bit key cipher.
Similiarly for RSA. It can factor numbers a lot faster than we can now, but if you pick your primes big enough you'll be safe.
Sadly, quatum encryption isn't much of a defence against QCs. It requires dedicated optical channels, which realistically are pretty rare (and you certainly can't use it over email).
Re:Not so close though (Score:2)
In the news today, a local overclocker and avid QuakeIII player died in an accident when his AMD Megatron 100,000,000 GHz suddenly overheated and self destructed.
Fellow gamer, who goes by the name "1337", was in a game at the time that the accident occured. "The last thing I remember he was up about 15,000 frags, and boasting about how he was getting 2,000,000 FPS on his machine." 1337 said. "Then suddenly he disappeared. Served him right, he had an unfair advantage."
Experts who have been investigating the accident have managed to peice together a probable chain of events. "From what we can figure, a pump failed in the cooling tower that he had in the back yard, and caused the chip to overheat" claims Cho Man Foo, a scientist at Los Alamos National Laboratory, one of the many expert quantum phyiscs experts called in to reconstruct the chain of events. "He may have survived the incident," states Mr. Foo, "except when the chip detonated, it started a chain reaction that caused the magnetic shiels around his Segate black hole quantum hard drive to collapse, imediatly consuming everything within 500 feet."
Pictures of the aftermath can be found here [primex.co.uk].
In related events, LAN party co-ordinators have been advised to postpone all further gatherings untill a meathod of confirming that no overclocked machines be used in game meetings. AMD and motherboard maker ASUS will be taking steps to insure that further incidents will not happen. In the next version of their products, the clock multipliers will be locked at the factory, hopefully preventing further injuries from their products. Also, tobacco giant Phillip Morris is suing AMD, claiming that the chips cause danger to their large customer base, and they could potentially loose a large number of customers if there was to be a major accident.
Related articles:
Overclocker Creats Rift in Space-Time Continuum [bbspot.com]
"Everything that can be invented has been invented."
Re:"Public key" isn't the problem (Score:1)
Until the theoreticians tell us whether or not P=NP on quantum computers, a good NP-complete encrytption algorithm will work just fine.
How about Optical Computers? (Score:1)
Instead of just on or off each 'bit' have have different states depending on the shade of light.
Imagine a system where a few thousand different shades of light are recognized.
Re:Wishful thinking... (Score:1)
In other words, using this analogy, we (humans) are a program with some random input (eg. body size, gender, hell.. anything), and a human life is simply that program executing, interracting with other 'programs' along the way. The program is already written, and it still takes Years to fully develop a 'person'. In addition, some people theorize that a person is Never fully developed, but I digress.
Therefore; maybe in 15 - 20 years, someone will have developed a complete learning 'program' that can be set free, and we'll see what happens. Plenty of people have already begun.
Of course, this is all a 'theory', and im certainly not an expert.. but it's interesting nonetheless.
-Egon
FYI: I'm filing the patent right now.... (Score:1)
Heisenberg Limits to Resolution? (Score:3)
Re:You're both right (Score:1)
Agreed. People like to come up with lots of examples to show how humans can use our mind to do things that a computer could never do, like look at code and find the infinite loop, etc. Unfortunately, when humans do these tricks, we dont use formal logic or exhaustive search to solve them (like most computers do), we use heuristics to guess as to what a good answer will look like and proceed from there. We form these heuristics from years or even decades of experience. To put it in laymans terms, we just make educated guesses. When we build a computer that can form its own heuristics, then give it decades of experience, I think we will see some amazing results.
Infinite loops? (Score:1)
Re:Not so close though (Score:1)
But when it comes, we will have to QUICKLY design a better encryption system than our current public-key based one !
What is the point of encryption? Someone out there is always going to be able to break it, and the net, because of its design and the weaknesses of the computers attached to it, will always be an unsecure channel of communication.
Quantum computers may the fastest brains on the earth, but how is that beneficial to the majority of people? Science? maybe.. running sims will certainly be faster.. but where is the advantage?
Smaller and faster seems to be the trend these days, but no quantum computer or 'next big thing' is going to change the way we do things. Computer technology isn't that different from what existed years ago... I would say we've maxed out the real potential of digital systems.. all they're good for are making our lives more complex, rushed, and information-swamped.
So why are people looking to the next wave of technology as some great savior? Wouldn't the greater advancement of the human species be when we've supplanted capitalism, advertising, and the supposed 'market-driven economy' with something a little less sensational for the media to turn around and cram down our throats?
I mean, really... quantum computers might be nice to have, but why not fix what's wrong with society first so we'll still be around to enjoy the toys?
I'm not ranting..just raving mad, hey... woo!
Chilled to a thousandth of a kelvin (Score:2)
Re:How does quantum memory work? (Score:1)
If there is a stumbling block for quantum computers, it is in engineering them. The math and physics behind them is sound. Engineering a qubit that maintains phase relationships with other qubits for a long enough period of time to carry out a calculation is the issue, not your superstition that spooky-fast solvers are impossible in principle.
Bingo Foo
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Re:How does quantum memory work? (Score:1)
No, IIRC, you only get exponential speedup if you can use a fourier transform to solve the problem. Search and factorization have been solved in this manner, but neither are NP-complete.
Quantom Computing still a ways away ... (Score:2)
will we see the dawn of Quantom Computing? I don't see why not ... but the sheer power, programming that would go in to it, and the understanding (hell it's still a thereom), will make this a reality further in the future ..
still is fun to dream ...
Discussion about manufacturing a quantum computer (Score:1)
Highly recommended reading.
Re:Wishful thinking... (Score:3)
I mean, I've always suspected that true, self aware computers might only be possible in a Quantum form.
Sure, we can do some excellent AI with faster Digital Computers, but for a system to be both intelligent and diverse it needs to be able to store a lot of data and process all of it quickly.
With today's computers, one can assume that the the more complex the information an AI is dealing with, and the more it "Learns" the more it has to process. Theoretically, this wouldn't be a problem for a Quantum Computer.
"Good morning computer."
"What's so good about it? You're just going to ask me to check your e-mail, read you the news at Slashdot, and give you the stock report. Then you're going to drink your coffee and head off to work, leaving me here alone as ussual. Good morning indeed."
"Everything you know is wrong. (And stupid.)"
A bunch of questions... (Score:1)
And the real burning question, how long has the NSA had one of these???
Thanks!
Some time ago... (Score:5)
Schmiedmayer, who's mentioned in the parent story, is also in this story from mid-last year.
A recent slashdot article [slashdot.org] that I submitted also concerns the aspect of using silicon buckyballs as cages for qubits.
The crux of the matter still remains unsolved in this SciAm article, and I have yet to see any explanation on how to solve it in any of the scientific journals that I read: that is, we don't use pure quantum states to preserve the very fickle quantum condition. When we can do that - there have already been enough postulation on what a qubit can consist of - then we can seriously consider quantum computing in the future.
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Re:Not so close though (Score:1)
Re:The end of encryption? (Score:1)
Timeline (Score:2)
Quantum::Superpositions (Score:2)
If you're interested in quantum computing, try to check out Damian Conway's talk on the Perl module Quantum::Superpositions [cpan.org]. It's very funny and actually quite useful!
Damian is travelling around the world talking to perl user groups. Check out his schedule [yetanother.org] to see if he's due to talk near you.
Lots of science articles (Score:1)
Claric
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Infinite computing?? (Score:1)
As far as I'm aware quantum computing just claims to work in a finite number of inputs simultaneously....I'm not too sure what it can do which is infinite.
Re:Wishful thinking... (Score:3)
Re:If you want to carry on where Feynman left off. (Score:2)
You might need a quantum computer to find the information necessary to build one. No wonder it's so difficult.
Infinite? (Score:2)
Now, I anticipating someone bringing up non-terminating Turing machines and untyped recursive lambda-functions as counter examples to my claim... Those don't represent computing! They are nothing more than short-comings of our formal systems. They have no logical meaning. Mathematicians, logicians, and computer scientists have put great effort towards gaining an understanding of computing that weeds out such nonsensical non-constructs.
An effective procedure that doesn't terminate with a result is not an effective procedure. Now, if by "infinite", you mean unbounded, then you have done nothing more than abuse terminology. "Infinity" does not mean the same thing as "unbounded", in a computational sense of the words.
Re:The end of encryption? (Score:2)
Feynman Lectures on Computation (Score:2)
Re:Feynman Lectures on Computation (Score:1)
How does quantum memory work? (Score:1)
Lots of articles about quantum computers talk about how processing is done and how fast it will be.
How does quantum memory work?
Are mass/heat constraints a problem?
The reason I ask is that a while back there was some interest in using the properties of chemical reactions, specifically the polymerization of DNA, to solve NP-complete problems fast. This strategy was used to solve some easy travelling salesman problems, for example. It was quickly pointed out, however, that to solve hard problems was going to take too much DNA. That is, the DNA system was fine for solving travelling salesman with 5 nodes, but 100 nodes (or something) would take converting the entire mass of the universe into DNA, so DNA computers are a dead end.
Are there similar constraints with quantum computers? Why not?
Re:Wishful thinking... (Score:1)
His theory is based on Goedel's theorem - basically a Turing Machine machine is weaker that a human mind because we can build formal mathematical proposition based on the Turing Machine's code, that that Turing machine won't be able to prove true or false (it's undecidable in the Turing Machine's formal system) but that we humans can prove true or false thanks to Goedel's theorem.
I personnaly don't subscribe to this theory because I feel his proof is weak around the edges - most importantly a human that proves a theorem doesn't produce the proof in the same sense that a formal system produces a proof. There's always room for a slight error in the human thought process.
On a sidenote, he doesn't give much insight on what he thinks quantum computers might be able to do for AI.
5 years my ass (Score:1)
Re:The true effects of quantum computers (Score:1)
***
Re:You're both right (Score:1)
Re:How does quantum memory work? (Score:1)
Don't working quantum computers, (in addition to easy factoring of large composites,) imply easy solution of all NP Complete problems? Some of the other mathematical implications are ever stranger. Whole classes of problems would go from insouble over the age of the universe, to trivial.
Re:Not so close though (Score:1)
Re:A bunch of questions... (Score:1)
It's likely any real-world quantum computer would employ a hybrid architecture. Considering we are unlikely to see commercial quantum computers outside the lab for at least a decade, conventional processors at that time should be somewhere in the 50-100GHz range for a desktop system. Even if some application has been discovered that needs the extra quantum boost, most things we do now will run more than fast enough on a conventional processor, and given the availability of conventional software it's likely most of the system will still use the conventional processor, calling out to the quantum system only for specialized tasks.
Tim
Not so close though (Score:1)
But when it comes, we will have to QUICKLY design a better encryption system than our current public-key based one !
Wishful thinking... (Score:3)
"In five years we will know if it's an interesting physics problem or if it's really something that we can use"
Unfortunately, this was the general opinion 5 years ago, and it will probably be the general opinion 5 years from now. It's like with AI, we're always on the cusp of a breakthrough, but that breakthrough never seems to come.
Ah well, someday...
Re:Not so close though (Score:1)
Well, I still believe that _a_ public system that relies on scrutiny by everyone will be more secure - just look at the last year and tha spate of security braks we've seen. At least with general scrutiny, these holes are likely to be found faster (which still can be a long tims, see the PGP alternate key situation
MagLev Rollercoasters (Score:1)
Quantum computers and Moore's law (Score:2)
The question is, who will have this technology? The early computers were the sole preserve of governments, but transistorised computers were more commonly seen in big businesses.
Early silicon based designs were bought solely by home hobbiest. Later silicon monsters once again went ot business, but this time those of all sizes. Will we see these more widely spread than the current breed, or more selectively targeted?
does this have anything to do with quantum leap? (Score:1)
huh, (Score:1)
sheesh.
The true effects of quantum computers (Score:4)
Quantum computation, however, is much more complex and much more interesting. Quantum computers are based on the concept of quantum entanglement, the ability of a quantum state to exist in a superposition of all of its mutually exclusive states: It's a 1 and a 0. However, this is not as easy to use as one might think. While it's true that if you have n quantum logic gates you have the ability to input 2^n data values simultaneously (as opposed to only 1 piece of data if you have n digital logic gates), this is not going to be the end of classical computing for a few reasons. First, quantum computers have to be perfectly reversible. That means for every output there's an input and vice versa. And there has to be no way of knowing the initial states of the data. You don't process data, you process probabilities in a quantum computer; if you know exactly what any one value is throughout the computation, you can find out all of the values: the superposition ends and you're stuck with a useless chunk of machinery. This means YOU CAN ONLY GET ONE RESULT FROM ANY QUANTUM COMPUTATION, THE END RESULT. You can't see what the data in the middle is or the computer becomes useless. (Landauer's principle makes heat loss data loss. When your processor gets hot, it's losing data. If the same thing happened to a quantum computer, it wouldn't be quantum anymore.) Decoherence is what happens when you randomly lose data to the environment by design, not by choice, and the superposition ends. This is bad for Q.C. Oh, and quantum computers can only do *some* things faster, like prime factorization and discrete logarithms. Not multiplication or addition. Plus, the circuits that would do basic arithmetic would be bigger and slower than what you've currently got.
So what does this all mean? It means that quantum computers are going to provide some advantages (real quick big number factorization), and some disadvantages (that whole RSA standard). The most realistic initial use of quantum computers will be as add-ons to existing super-computers to resolve certain types of NP-Complete headaches that regular math can't simplify yet. At best they will someday be an add-on to your PC; but they will never replace the digital computer.~
If you want more info, check out ahttp://www.qubit.org [qubit.org], it's got some decent tutorials.
Re:Not so close though (Score:1)
If you want to carry on where Feynman left off... (Score:2)
Papers, 1933-1988. Feynman's correspondence, course and lecture notes, talks, speeches, publications, manuscripts, working notes and calculations and commentary on the work of others are all included in this extensive collection.
Collection size: 91 boxes, 39 linear ft.
That's a big twinkie.
Re:Quantum computers and Moore's law (Score:1)
Re:The true effects of quantum computers (Score:3)