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Under the Hood of Quantum Computing
Posted by
ScuttleMonkey
on Sun Aug 20, 2006 05:26 AM
from the fun-facts dept.
from the fun-facts dept.
nanotrends writes "Gordie Rose, the CTO of Dwave Systems, the venture funded company that plans to offer paid use of a superconducting quantum computer starting in 2007, reveals secrets of his quantum computer construction. It is based on nobium superconducting 'circuits of atoms' and is not RSFQ. (Rapid Single Flux quantum)."
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Advantages? (Score:5, Interesting)
I'd be very suprised if their quantum computer will be faster than conventional computers by next year. 20 years away, maybe.
Re:Advantages? (Score:5, Interesting)
Parent
Re:Advantages? (Score:5, Insightful)
Parent
Re:Advantages? (Score:5, Funny)
Parent
Re:Advantages? (Score:4, Interesting)
(Try "Schrodinger's cat" or the "Heisenberg uncertainty principle")
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It's a *quantum* computer (Score:3, Funny)
Re:Advantages? (Score:5, Informative)
Well, it's a quantum computer. Given the problem it might be like trying to make your CPU compete against a GeForce or ATI. If you try to do it all with CPU emulation, there's not much doubt who'll win. That said, I got the impression that current quantum computers have a so limited number of qbits (the computing power pretty much grows to 2^n with n bits), that it's faster and cheaper to just cycle through all 2^n possibilties one at a time. Currently the largest I've seen is a 12 qbit computer [blogspot.com]. Now 2^12 = 4096 states at once is a nice curiosity but nothing that makes my encryption keys worry. Basicly it's man vs Deep Blue at computer again - the quantum computer is great at testing many solutions at once but the sheer computing power of traditional computers takes home the victory. Now, if they can get hundreds of qbits together things will change massively. But the difficulty in keeping all those in a cohesive quantum state also raise drastically, so I think we're far off from a usable quantum computer.
Parent
Re:Advantages? (Score:5, Informative)
I think the point of the article is that D-Wave Corp claims to be able to create qbits from "large" objects (ie; large enough to be fabricated using standard IC fabrication techniques), but with niobium rather than silicon. This enables them to create a quantum computer without all the hassle of having to manipulate individual atoms as the present research lab quantum computers do. From the article:
Since supercooling is required, it's highly unlikely that you or I will be able to afford one of these things any time soon (assuming it's not all marketing hype in the first place), but you can be assured the NSA and other government "intelligence" agencies will be able to afford as many as they want because of all the tribute they demand from us on pain of imprisonment, in the form of exorbitant taxation.
Parent
Re: (Score:3, Interesting)
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+
2) Dismantling of public-funded education
=
Aristocracy within 2 or 3 generations because the concentration of wealth at the top will far exceed the paltry pittance at the bottom. People complain about wealth at the top today -- wait til the Gilded Age of Libertarianism takes over.
Did you know Libertarian arguments favor child labor?
1) It's the parent's right to force a child to work. This has been the case for pretty much ever. Parents force their kids to do chores. Parents regularly em
Re:Advantages? (Score:5, Informative)
Parent
Re:Advantages? (Score:4, Informative)
Two points: what other states, and how do you propose we measure them? Quantum bits will typically have only the 1/on and 0/off states, by design - partly because it meshes well with our classical computing methods, and partly because most make use of concepts like spin which are naturally in up/down or the like. When isolated, they evolve into a state expressed by a|0> + b|1>, where a and b are the probability that you will observe the 0 state or the 1 state, respectively. This superposition state is impossible to observe, since the wavefunction collapses into one or the other on observation, so we can only observe either the 1 or the 0. More generally, you have a state for the entire register which is the superposition of every possible 'classical' state, with individual probabilities of being observed when you check the register of a, b, c and so forth.
Also, your post makes little since, everything is observed, which is why it exists, just because it isent observed by humans dosent mean its not observed,
This is very true, in general, and is the very reason why quantum computing is hard. The qubits have to be completely isolated from everything except the read/write mechanism, so that these particles will only be observed by humans, and nothing else, otherwise many of the requirements to make a quantum computer effective cannot be reasonably achieved.
Parent
Re: (Score:3, Informative)
Everything is not observed. It cannot be observed. Mathematically there are certain things that cannot be observed, but that still exist, and can still be interacted with.
The mathematics of quantum mechanics suggests that certain things happen so long as there's no attempt to observe them. There are all sorts of crazy experiments that verify this result, but in summary it's as you read: under quantum mechanics there are things that are certain ways only so long
Re:Advantages? (Score:4, Interesting)
I'm sure the NSA and other government agencies have a passing interest in code breaking, which among other things means being able to factor huge numbers quickly [rsasecurity.com]. A quantum computer would (if it contained sufficient logic cells) be able to try all possible factors of a number at the same time, and would thus be able to factor any number almost instantaneously. It would mean the death of most common types of encryption that depend upon the difficulty of factoring as a means of insuring the privacy of data. After all, the government probably has petabytes of encrypted data from their nationwide wiretapping of telephone and Internet [sc.edu] communications they would love to be able to decrypt quickly.
Parent
Re:Advantages? (Score:5, Informative)
The NSA has been advising the security community against using RSA-style encryption for some time now - it's not like they're trying to keep the weakness a secret for some nefarious reason.
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QP =? NP (Score:3, Informative)
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Also note that factorization hasn't been *proven* NP-hard, so there may be a different explanaiton for the NSA's advice. They are the world's largest employer of math PhDs, after all, and it's just possible they know something we don't.
I
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A Brief History of Quantum Computing [ic.ac.uk] contradicts all your quantum-computing assertions: "In effect, a calculation performed on the register is a calculation performed on every possible value that register can represent." That's in its description of Shor's algorithm, which also contradicts your feedback-driven characterization, saying it produces very-likely factors and succeeds by simply retrying until one of its answers works.
That link also describes Grover's algorithm, cutting brute-force search from
Re:Advantages? (Score:4, Informative)
I read the article, but it didn't make it very clear - what will be the advantages of paid use of their quantum computer? Unless it's going to be faster than other supercomputers, I can't see the point. Is there some other advantage I'm not aware of?
Yes, of course the goal is to be substantially faster than other supercomputers: for certain classes of problems. These are outlined on the company's website ( http://www.dwavesys.com/optimization.php [dwavesys.com] ) and ( http://www.dwavesys.com/quantumcomputing.php [dwavesys.com] ). But if you want a "Neutral Point of View" , I'll quote wikipedia:
From D-Wave's website:
Parent
Re:Advantages? (Score:4, Insightful)
Lance Fortnow posted a very nice summary of this on his blog: [fortnow.com]
Parent
Re:Advantages? (Score:4, Insightful)
Or think about material sciences. Again, the basic (quantum) equations are well known, but are too large to calculate directly. Again, a quantum computer might be very helpful. It's hard to say what advantages the new materials might bring us (maybe room-temperature superconductors?), but it's allmost certain that there will be some advantage.
Parent
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If anyone is interested in how quantum computers can (at least may be able to) appoximately solve TS
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-Eric Kincl
Au contraire (Score:2)
Just a guess. Given the article, one can't do anything other than guess. I think this may be a conventional computer using superconducting technology, not a 'quantum computer' as the term is usually understood. It seems to be expected that a superconducting computer -- if one can be built -- might clock an order of magnitude faster than conventional semiconductor based compu
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The idea, I guess, is that you take a NP-hard problem such as the traveling salesmen, and encode it in the initial conditions of their circuit, which is initially in a non-equilibrium state. Then you allow the circuit to evolve and reach equilibrium while respecting certain boundary conditions devised according to t
"Quantum" computer is misleading (Score:5, Insightful)
Wow, they use quantum mechanics? Every chemical reaction in our universe uses quantum mechanics; they couldn't be more vague if they tried. They're clearly trying to capitalize on the 'quantum computer' buzz.
Re:"Quantum" computer is misleading (Score:5, Informative)
Parent
"like getting two qubits to interact..." (Score:3, Informative)
Paul B.
Woo Woo science (Score:5, Insightful)
I used to be a undergrad lab assistant. I never worked in quantum computing, but our neighbours were some of these guys [www.iqc.ca]. I picked up a few things, one of those things being that quantum computing is hard.
Classical computers use the laws of classical physics to operate. Classical physics is deterministic, and that's how we want our classical computers to behave. As the chip and die sizes get smaller and smaller (what are we at now, 65nm?) CPUs are more likely to suffer from quantum effects, but AFAIK there's circutry in there to compensate for that. Error checking.
A quantum computer is just a machine that uses the laws of quantum mechanics rather than the laws of classical mechanics to operate. The advantage is that some algorithms, when implemented on a quantum computer, are 2n instead of n^2. I never really understood this, maybe a better physicist will come along and explain it. Anyway, to build a quantum computer one needs two things:
- (a) You need some Quantum bits (qbits) to store data
- (b) You need to get those bits to interact with each other in some fashion
There are many approaches to building a quantum computer. One guy (Raymond Laflamme) has a bunch of different atoms that are different elements all in the same molecule, those interact with each other but he has only developed the ability to read / write to about 5 different qbits. I read about another guy on Slashdot here who made a giant array of qbits using atoms in a laser trap. That gets you a lot of qbits, but they don't interact at all. There are many approaches.
Anyway, the reason I think Dwave Systems is full of bullshit is that any approach thus far is good at (a) or (b), but not both. Someone who got a powerful quantum computer up and running would most assuredly win a Nobel Prize. Also, why the hell would he need to woo venture capital? I know I'm up in Canada, but I'm sure most governments are throwing scads and scads of research money at Quantum computing. Answer? Venture capitalists are more naive.
If there's anything I learned from here [randi.org], it's that a lot of Con artists use buzzwords to try and justify their woo-woo science. "Quantum" is one of them.
Smart money on this guy being a fraud.
Re:Woo Woo science (Score:5, Funny)
Parent
ACK (Score:3, Informative)
There are only two Quantum Algorithms with applications in real live AFAIK Shor's factoring Algorithm to find the Prime Factors of a number in polynomial time, and a boosted search algorithm, which gives a \sqrt(O) speed boost. The largest number Shor's Algorithm could be used on is 15. And it won't be usefull before we reach 16 bit's or so (which we won't in my lifetime with any
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Re:Woo Woo science (Score:5, Insightful)
Though a transister does use Quantum Mechanics to function, it is a discrete unit (a "black box" if you will) with a preidctable outcome. A quantum computer, on the other hand, uses a property of QM known as "superposition of states". A qbit in a quantum computer isn't 0 or 1, but some combination of 0 and 1 at the same time. It's only when the qbit is "observed" (read) that it becomes a 0 or 1.
If we can get these qbits to interact with each other without reading them (or "collapsing the wavefunction", in quantum mechanics lingo) then we can have various superpositions of 0s and 1s interacting with each other within an algoritm. Essentially the algorithm run by the quantum computer is acting in parallel with itself. When we observe the qbits when the algoritm is finished, we see the desired result. I know that sounds like magic, but I've probably explained it poorly. I've explained it better in the past. [uwaterloo.ca]
Incidentially, someone who is uneducated (not stupid, mind you, just uneducated) may have difficulty distinguishing between the BS in the original article and the more scientifically accepted BS I've spouted. See? That's how these con artists are allowed to succeed!
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The guy is a *tad* optimistic (Score:3, Funny)
BTW all circuits on the lowest level are "quantum" circuits, so maybe he's just trying to pass off his Packard-Bell 66MHz PC as a quantum computer?
It just sounds a lot like a RSFQ chip. (Score:4, Informative)
Carl Sagan Said it Best (Score:3, Interesting)
I paraphrase:
"extraordinary claims require extraordinary evidence"
Yet another under construction web page and half baked idea. I pity the investors. And remember what Feynman said (which is still true today):
"No one understands quantum mechanics"
Which does not keep us from using the results of a a highly successful theory, but just keep in mind, wave function computing is not going to be easy, but I believe it is possible. And I should know, I'm made of atoms.
Do they know what they are talking about? (Score:3, Interesting)
I think this statement is incorrect [wikipedia.org]. My understanding concurs with what is written in the wiki article:
and
Low power CPU vs enormous cooling costs?? (Score:2)
"Historically arguments for metal-based processors have been that (1) since they're made out of superconductors, they generate much less heat than conventional processors (true); (2) for some technical reasons you can operate at clock speeds up to about 100 GHz without alot of problems (true); so if you want a really fast, really low power processor, here's a way to do it."
Ok, sure you've got a low power CPU but what about the massive amounts of energy expended to keep it at absolute zero? This does
Financial expert wanted (Score:2)
MIT Technology Review Article on DWave (Score:4, Informative)
[technologyreview.com] http://www.technologyreview.com/read_article.aspx? id=14591&ch=infotech [technologyreview.com]
Computers have infiltrated nearly every field of business and science, and they keep getting faster. Nonetheless, researchers routinely encounter problems impossible for even the most powerful supercomputers to solve. The remedy could be quantum computers, which would use the fantastic properties of quantum mechanics to crack such problems in seconds rather than centuries. Since the 1980s, physicists in academic labs and at firms such as IBM, Hewlett-Packard, and NEC have pursued a variety of quantum computing approaches, but none seems likely to deliver a working machine in less than 10 years.
Company: D-Wave Systems
Headquarters: Vancouver, British Columbia
Amount invested: $22 million Canadian (about $17.5 million U.S.)
Lead investor: Draper Fisher Jurvetson
Key founders: Geordie Rose, Alexandre Zagoskin, Bob Wiens, Haig Farris
Technology: Quantum computers
Vancouver startup D-Wave Systems, however, aims to build a quantum computer within three years. It won't be a fully functional quantum computer of the sort long envisioned; but D-Wave is on track to produce a special-purpose, "noisy" piece of quantum hardware that could solve many of the physical-simulation problems that stump today's computers, says David Meyer, a mathematician working on quantum algorithms at the University of California, San Diego.
The difference between D-Wave's system and other quantum computer designs is the particular properties of quantum mechanics that they exploit. Other systems rely on a property called entanglement, which says that any two particles that have interacted in the past, even if now spatially separated, may still influence each other's states. But that interdependence is easily disrupted by the particles' interactions with their environment. In contrast, D-Wave's design takes advantage of the far more robust property of quantum physics known as quantum tunneling, which allows particles to "magically" hop from one location to another.
Incorporated in April 1999, D-Wave originated as a series of conversations among students and lecturers at the University of British Columbia. Over the years, it has amassed intellectual property and narrowed its focus, while attracting almost $18 million in funding, initially from angel investors and more recently from the Canadian and German governments, and from venture capital firms. The company plans to complete a prototype device by the end of 2006; a version capable of solving commercial problems could be ready by 2008, says president and CEO Geordie Rose.
The aggressiveness of D-Wave's timetable is made possible by the simplicity of its device's design: an analog chip made of low-temperature superconductors. The chip must be cooled to -269 C with liquid helium, but it doesn't require the delicate state-of-the-art lasers, vacuum pumps, and other exotic machinery that other quantum computers need.
The design is also amenable to the lithography techniques used to make standard computer chips, further simplifying fabrication. D-Wave patterns an array of loops of low-temperature superconductors such as aluminum and niobium onto a chip. When electricity flows through them, the loops act like tiny magnets. Two refrigerator magnets will naturally flip so that they stick together, minimizing the energy between them. The loops in D-Wave's chip behave similarly, "flipping" the direction of current flow from clockwise to counterclockwise to minimize the magnetic flux between them. Depending on t
I guess Josephson junctions and/or vaporware (Score:3, Informative)
In any case, the technology that comes to mind when I hear "very cold superconducting niobium quantum computer" is Josephson junctions [wikipedia.org]. There's an article on it here [arxiv.org].
What people does DWave have? What have they published previously?
Yes, it IS Josephson junctions (Score:2)
Re:RTFA, WTF? (Score:4, Informative)
For starters; a link to the company's website instead of somebody's "See Spot run" blog post:
http://www.dwavesys.com/quantumcomputing.php [dwavesys.com]
KFG
Parent
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While I completely agree, it seems enough to get funding. A sad state of affairs, indeed.
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True. But this has zero potential. So it should not be funded.