Under the Hood of Quantum Computing

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)."

Advantages?

[Zouden]

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?

I'd be very suprised if their quantum computer will be faster than conventional computers by next year. 20 years away, maybe.

Re:Advantages?

[QuantumG]

I don't think anyone can assess the capabilities of his systems from that article. I also don't think that was unintentional.

Re:Advantages?

[Mathinker]

Uhm, from the article, nobody can even assess whether it really is a quantum computer.

Re:Advantages?

[mickwd]

Or, following the principles of Heisenburger's Uncertain Cat, we can determine if it really is a live quantum computer, but we can't know where it is.

Re:Advantages?

[EJB]

Not to mention Darwin's apple or Rembrandt's Mona Lisa. ;-)

(Try "Schrodinger's cat" or the "Heisenberg uncertainty principle")

Re:

[Kagura]

Very clever, I wish I had mod points :)

Re:

[mickwd]

I guess that's what I get for trying to tell a joke on a US Web Show without a laughter track in the background.

Re:

[Digi421]

Or if you would know where it is, you'd never be able to figure out how fast it really is.

It's a *quantum* computer

[WilliamSChips]

If you assess the capabilities of the system, it disappears!

Re:Advantages?

[Kjella]

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.

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.

Re:Advantages?

[RKBA]

"Now, if they can get hundreds of qbits together things will change massively."

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:

Superconductors are the only type of material that we know of where big lithographically defined devices (like really big. Like centimeter on a side big.) can be built that behave just like they were atomic-sized.

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.

Re:

[StikyPad]

Except that taxation is an illusion, since the government creates the money. What they're really doing is pretending to give it to you. The most obvious version of this is that government workers pay taxes, but we're all government workers indirectly, since we work for the government's money. If taxation did not exist, salaries would just be lower. You wouldn't make any more money, and even if you did, everyone else would too, which means inflation would increase to offset the extra cash. Remember, inf

Re:

[volkris]

That's a pretty flawed worldview.

1) The US government doesn't create money; it creates US dollars, which are not equivalent to money.

2) Salaries aren't set by taxation. Salaries are set by the amount of wealth one generates, which is completely independent of operations of the government. Without taxation salaries would rise since there would be larger money supply available to create more wealth.

3) Inflation is mostly set by the money supply in general, not disposable income. Business to business exchanges

Re:

[Luyseyal]

Without taxation salaries would rise since there would be larger money supply available to create more wealth.

Sure sounds good on paper, doesn't it? The Libertarians would have you believe that the government is responsible for corporate domination, yet, Libertarian policies are, in effect, an (accidental?) attempt to return us to the Age of Aristocracy. Aristocracy may make the country look wealthy, but there will be plenty of emptier pockets to go about.

IMHO,
-l

Re:

[Delphiki]

The best part of your post was the part where you provided all that evidence to back up your claims.

Re:

[Luyseyal]

1) No gov't oversight
+
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:

[hswerdfe]

Not that I disagree or anything, but I think your are confusing
"Aristocracy" : rule by the best
with
"Plutocracy" : rule by the wealthy
And many would say that many of the western so called democracies are already Plutocracies.
and not just moving that way.

Re:

[Luyseyal]

I'm talking about a Plutocracy becoming a de facto Aristocracy (rule by hereditary nobles. Dictionary.com definition 1.).
-l

Re:

[Anonymous Coward]

i think you need to relook at your understanding of computers.

Its true, conventional boolean logic computers grow 2^n. But thats because its "bit" is a boolean value, it can only have 2 states, thats where the "2" comes from. A quantom computer would be x^n where x is the number of states a bit can be in, while n is the number of bytes. The articel dosent give any information besides a link to the paper (im to busy), the "12" they spoke of could mean as you took it, to be the number of bits, but that is

Re:Advantages?

[ZombieWomble]

I do believe you're mistaken. Quantum bits are exactly like regular bits in their possible observable states - that is, they are either "on" or "off" when observed. The interesting part of quantum computing comes from the fact that, when they're not being observed, they exist in a superposition of both "on" and "off" states. Now, if you put 8 of these bits together, you have a 'qbyte' which, while when it's observed it can only represent the same range as a regular byte, can be used in calculations representing every single possible permutation of the data at once - i.e. every number from 0 through 255. Each bit you add doubles the number of states you can simultaneously test using this superposition property - this is what the GP meant when he said that quantum computing scales as 2^n.

Re:Advantages?

[ZombieWomble]

That sounds rather stupid. Why only test for "on" or "off" when you can test for any of the states?

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.

Re:

[volkris]

That's not really how quantum mechanics works.

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:

[Mac Degger]

I agree...but did you see the article about the guys at Delft uni? They've built and operated a silicon circuit which can 'trap' a qubit. Dunno about exact decoherence rates (I'll ask), but the circuit works, and becasue it is pure silicon, it can be massproduced NOW. And no supercooling neccessary!

Re:Advantages?

[RKBA]

"what will be the advantages of paid use of their quantum computer?"

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.

Re:Advantages?

[lgw]

As far as I know, only RSA-style cryptograophy is affected by quantum computing. There are other ways to do public key encryption, such as elliptical curve cryptography [wikipedia.org] that should be unaffected, as they depend on a different class of problem being hard, and of course quantum computing won't help with symmetric key crypto at all.

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.

Re:

[RKBA]

I don't claim to be a mathematician, but it's pretty easy to show that factoring is a boolean satisfiability (SAT) problem [wikipedia.org] and is generally believed to be at least NP-Hard, if not NP-complete as SAT is. Consequently, if factoring could be "solved" (ie; performed "easily" by use of quantum computing or other means) then any other NP problem could be cast in terms of a SAT problem for easy solution. That would mean P=NP, would it not?

QP =? NP

[benhocking]

Actually, it would mean that QP = NP. This is considered more likely than P = NP, but as with P=?NP no one has yet shown it to be true or false.

Re:

[RKBA]

LOL! It took me a few seconds to get the joke, but after I couldn't find a definition of "QP" anywhere, I realized you probably meant it to be "Quantum Polynomial" time, and so your QP = NP means that P = NP iff you have a quantum computer. Right? Har, har. ;-)

Re:

[lgw]

That's the promise of Quantum Computing. I'm quite skeptical, but given the NSA is suggesting that one rely on ECC instead, there's something brewing: the NSA has given *very* good advice historically, though it has sometimes taken the private sector decades to understand.

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

Re:

[lgw]

can see that the NSA would have had the budget to brute-force crack such keys at least a decade before the public crack.

Of course this would have been true regardless of the number of bits in the key, but then I've never been much of a fashion consultant for tinfoil headware.

Not a joke

[benhocking]

I've seen the term QP used before at a quantum computing seminar. I certainly didn't coin it. There is a very important distinction between P and QP - namely that QP is, as you guessed, a polynomial time algorithm on a quantum computer. Google on "Quantum Polynomial" and NP if you want more info. Here's a link that Google Scholar turned up, as well (I haven't read it, but it sounds interesting - judging from the title it seems they are claiming that QP=NP): http://scholar.google.com/url?sa=U&q=http://ar [google.com]

Verifiable in P

[benhocking]

All NP problems are verifiable in P. So, although probability does still factor in (because in many situations there's a significant chance the correct answer won't come up), you can verify you have the right answer in P.

Can be converted to 3-SAT

[benhocking]

As I recall, the travelling salesperson algorithm (I assume this is what you meant by TSP) can be converted to a satisfiability problem in polynomial time. Furthermore, it is trivial to verify the satisfiability problem in polynomial time. Are you arguing that TSP cannot be converted to SAT (or 3-SAT, as is usually done) in P, or that 3-SAT is not verifiable in P?

Re:

[lgw]

It seems that the most interesting part of all of this is that, while all problems in NP had been assumed to be "equally hard", this might not actually be the case with a quantum computer.

Re:

[Anonymous Coward]

Factoring may a SAT problem, but that doesn't mean SAT is always a factoring problem. All that says is that a SAT solver could solve factorization.
Prime factorization is in NP, so if it is proven NP-Hard, it must be NP-Complete.

I think it will.

[jthill]

won't help with symmetric key crypto at all

If you have any known plaintext, anywhere, your symmetric key is toast: Q will just try every key at once and select what produces that text. AES is a good deal simpler than multiplication (presuming that there's no magical direct method — the hits I get on "quantum multiplication" might as well be encrypted).

Re:

[lgw]

There's no evidence that I know of that this is possible in the general case. A quantum computer is not some infinitely-parallel magic for solving all possible enumerative math problems instantly. Assuming, of course, that QC can actually be made to work on real problems at all, which has not been demonstrated to an engineer's satisfaction, QC merely makes the correct outcome more probable when guessing.

Shor's algorithm to factor large number quickly with QC relies on feedback: a near-miss is useful for r

Re:

[jthill]

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:

[lgw]

People believe all sorts of things about quantum computing, perhaps we'll see a demonstaration one day to clear the air. Perhaps not. I'm extremly skeptical of inventions that only work on PowerPoint slides.

In any case, having a block of known plaintext only makes the problem trivial if you know exactly what block of cyphertext it corresponds to, which you seem to be assuming is the case. Granted, if you have a known plaintext block (after known compression), and know the corresponding cyphertext block,

Re:Advantages?

[smallpaul]

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:

It is widely believed that if large-scale quantum computers can be built, they will be able to solve certain problems faster than any classical computer...

Integer factorization is believed to be computationally infeasible with an ordinary computer for large numbers that are the product of two prime numbers of roughly equal size (e.g., products of two 300-digit primes). By comparison, a quantum computer could solve this problem relatively easily. If a number has n bits (is n digits long when written in the binary numeral system), then a quantum computer with just over 2n qubits can use Shor's algorithm to find its factors. It can also solve a related problem called the discrete logarithm problem. This ability would allow a quantum computer to "break" many of the cryptographic systems in use today, in the sense that there would be a relatively fast (polynomial time in n) algorithm for solving the problem....

This dramatic advantage of quantum computers is currently known to exist for only those three problems: factoring, discrete logarithm, and quantum physics simulations. However, there is no proof that the advantage is real: an equally fast classical algorithm may still be discovered (though some consider this unlikely). There is one other problem where quantum computers have a smaller, though significant (quadratic) advantage. It is quantum database search, and can be solved by Grover's algorithm. In this case the advantage is provable. This establishes beyond doubt that (ideal) quantum computers are superior to classical computers.

From D-Wave's website:

For several decades, computer scientists have been trying to classify all of the problems we know of. Whenever a new problem comes up, it is placed in one of the existing categories of problems. These categories describe how difficult the problems within it are, and why.

One of the most interesting categories contains problems that are called NP-complete. These all have the feature that in order to solve the problem all possible solutions must be tried, and the number of possible solutions grows exponentially with the problem size.

An example is the Travelling Salesman Problem, although there are literally thousands of them. This category is a particularly interesting target from a commercial perspective because most real-life business problems are in it.

...

Quantum computers can be used to get approximate solutions to large NP-complete optimization problems much more quickly than the best known methods running on any supercomputer.

Re:

[Anonymous Coward]

> Quantum computers can be used to get approximate solutions to large NP-complete optimization problems much more quickly than the best known methods running on any supercomputer.

Ahh. Let's break it down, shall we?
NP-complete are decision problems (yes or no), not optimization
*approximate* solutions for NPC - we know how to do those in polynomial time, you don't exactly need a quantum computer there; it's the exact solutions that are hard
approximate solutions for *NPC* - they do however not transform ver

Re:Advantages?

[PatriceVignon]

One of the most interesting categories contains problems that are called NP-complete. These all have the feature that in order to solve the problem all possible solutions must be tried, and the number of possible solutions grows exponentially with the problem size. An example is the Travelling Salesman Problem, although there are literally thousands of them. This category is a particularly interesting target from a commercial perspective because most real-life business problems are in it. ... Quantum computers can be used to get approximate solutions to large NP-complete optimization problems much more quickly than the best known methods running on any supercomputer.

Sorry, but that is simply not true. If you have a classical NP complete problem (e.g. Travelling Salesman), you can solve it by trying out exponentially many steps, 2^n, and most people believe that you cannot find faster (classical) algorithms. With a quantum you can improve this to 2^(n/2) by the so-called Grover search algorithm. This is not nearly enough to make these problems tractable in practice. And to make things worse, this "speed-up" will most likely be eaten up by the necessary error correction.
Lance Fortnow posted a very nice summary of this on his blog: [fortnow.com]

But I'm not a physicist or an engineer and suppose we can overcome these obstacles and actually build a working machine. Then I can imagine the following conversation in 2025:
Quantum People: We now have a working quantum computer.
Public: Yes after 30 years and 50 billion dollars in total funding. What can it do?
Q: It can simulate quantum systems.
P: I'm happy for you. What can it do for the rest of us?
Q: It can factor numbers quickly.
P: Yes, I know. We've had to change all of our security protocols because of your machine. Does factoring have any purpose other than to break codes?
Q: Not really. But we can use Grover's algorithm for general search problems.
P: That sounds great! So we can really solve traveling salesperson and scheduling problems much faster than before?
Q: Not exactly. The quadratic speed-up we get from Grover's algorithm isn't enough the offset the slow-down by using a quantum computer combined with error correction. But we can solve Pell's equation, approximate the Jones polynomial and a few other things very quickly.
P: Are those algorithms particularly useful?
Q: No.
P: They why did you build a quantum computer?
Q: Because we could.

Re:Advantages?

[maxwell demon]

Of course being able to efficiently simulate quantum systems would do a lot for many people. Let's start with quantum chemistry. When you deal with large molecules (as f.ex. in pharmacy), you are basically solving a large quantum system. The basic equations are well known, but the size of the problem is what makes it difficult. A quantum computer could resolve this problem. Or in other words, quantum computers might cause more health for the people.

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.

Re:

[QuantumFTL]

An example is the Travelling Salesman Problem, although there are literally thousands of them. This category is a particularly interesting target from a commercial perspective because most real-life business problems are in it. ... Quantum computers can be used to get approximate solutions to large NP-complete optimization problems much more quickly than the best known methods running on any supercomputer.

If anyone is interested in how quantum computers can (at least may be able to) appoximately solve TS

Re:

[Hobadee]

Advantages? ADVANTAGES!? Dude, think, your framerate for Counter-Strike will RULE!

-Eric Kincl

Au contraire

[vtcodger]

***I'd be very suprised if their quantum computer will be faster than conventional computers by next year. 20 years away, maybe.***

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

Complete nonsense

[Anonymous Coward]

This article is total crap. IAAP (figure it out) in the field of spin based electronics, closely aligned with efforts to develop qc. As described in the article, these circuits are not quantum bits. Nb metal that is held at low temp will enter the so called "ground state" of the material where all electrons are in a single state. Great. you have a macroscopic quantum state. Problem is that superconducting states do not exist outside of the superconducting metal. in fact they have a region of "normal

Re:

[citanon]

Their computer is a generalized effort to simulate the running of a subset of computer algorithms with the behavior of a bunch of electrons tunneling around in a series of superconducting wires.

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

Re:

[syousef]

They're trying to create a quantum tunnel into your pocket.

Re:

[Vadim Makarov]

Even if it has no practical use, there will be researchers from other places who rent it, to do proof-of-the-principle experiments and such stuff without building their own devices.

RTFA, WTF?

[ricky-road-flats]

I just read the FA, and it makes only a token mention of quantum computing at the end. It seems to be a (very simple) discussion of using a superconductor to make faster transistors.... What have I missed here?

Re:RTFA, WTF?

[kfg]

... What have I missed here?

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

Re:

[maxwell demon]

Well, if you can switch between superconductivity and normal conductivity (maybe even with a large resistance in the non-superconducting state state), then it would make sense, I didn't RTFA, but I could imagine that this is possible by creating a magnetic field at the superconducting wire (large enough magnetic fields make superconductance break down). Then you could have e.g. superconducting state = no resistance = no voltage on the wire = 0, and normal conducting state = resistance = voltage on the wire

"If you can switch..."

[PaulBu]

Congratulations! You've just invented the earliest attempt to build superconductive electronics (SCE), dating back to late 50s, or something -- quantrons these gates were called (I think, way before my time...), controllable by neighboring magnetic fields and using SC/non-SC to distinguish between ``1'' and ``0''.

In early 60s Brian Josephson discovered interesting properties of what became to be known a Josephson junction, a tunnel barrier between two SC which would be superconducting or normal depending on

"Quantum" computer is misleading

[kestasjk]

What D-Wave has done is begun with the standard approaches to building metal-based processors and modified them in such a way that these processors use quantum mechanics in order to accelerate computation.

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

[slashdotmsiriv]

From dwave's site: "There are many potential ways to build quantum computers (QCs). Of these, four types have emerged as being most likely to succeed. These are based on (A) assemblies of individual atoms trapped by lasers; (B) optical circuits, for example using photonic crystals; (C) semiconductor-based designs, usually including atomic-scale control of dopant atom distribution or quantum dots; and (D) superconducting electronics. D-Wave focuses exclusively on superconducting electronics. This is because superconductors have the unique property that very large structures can be built out of them that behave according to the rules of quantum mechanics. Because of this, design of superconducting QCs does not require new technology development. This is in contrast to the other three types of QCs, in which information is stored using atoms or individual photons (particles of light), and controlling and manipulating this information requires technologies that do not yet exist. The two superconductors used to build QCs are aluminum and niobium. At room temperature these materials are metals. When they are cooled down close to absolute zero, the electrons in the metals pair to form particles called Cooper pairs. These particles carry charge in the superconductor. Cooper pairs are very different from electrons. One key difference is that Cooper pairs are what physicists call bosons, while electrons are fermions. Bosons are allowed to occupy the same quantum state, while fermions are not. In a superconductor, all the Cooper pairs can (and do) exist in exactly the same state. This means that all of the charge carriers in the superconductor are fundamentally linked. They directly inherit their behavior from the scale of a single Cooper pair. One way to think of this is that a chunk of superconductor amplifies the quantum effects that exist at the level of extremely tiny individual particles up to the scale of the whole chunk, even if the chunk is very large. This amplification of quantum effects is responsible for the well-known properties of superconductors, such as zero resistance to current flow and exclusion of magnetic field. It is also extremely useful for building components of QCs. Superconductors naturally shield themselves from external noise, creating a safe haven for quantum effects. This ability to build large things that behave like small things overcomes many practical problems in building real QCs."

Re:

[caffeinated_bunsen]

Let's run Bunsen's Bullshit-O-Meter(tm) over this real quick:
There are many potential ways to build quantum computers (QCs). Of these, four types have emerged as being most likely to succeed. (A) ... (B) ... (C) ... (D) ...
[..........]

This is because superconductors have the unique property that very large structures can be built out of them that behave according to the rules of quantum mechanics.
[*.........]

Because of this, design of superconducting QCs does not require new technology developmen

"like getting two qubits to interact..."

[PaulBu]

Check out the sidebar under "Published Stuff", especially this [arxiv.org] link... Next objection, please...

Paul B.

Re:

[Sinbios]

Actually, I think the point is they ARE trying to be as vague as they can :P

Woo Woo science

[Valacosa]

A functional quantum computer? Really?

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:

[kfg]

. . . 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.

You'd almost think that there was some sort of undetermanism at work or something.

KFG

Re:Woo Woo science

[Iwanowitch]

any approach thus far is good at (a) or (b), but not both.

Ooh, Heisenberg-approaches!

Re:

[gsn]

No, no - if Heisenberg approcahes the real question is where is he? BTW mods I think that parent is "Funny" as opposed to "Informative" unless we must have sigma Funny sigma Informative >= hbar/2 in which case since hes marked informative no body can ever know how funny he is....

Re:

[grrrgrrr]

Hey I think we are already using quantum computers. Computers that use the laws of classical physics to operate have to use vacuum tubes. Semiconductors are very much a product of the quantum mechanics. The effects of semiconductors where known before and used in crystal radios but where not really understood the same is true for for-example the photovoltaic effect .

Re:Woo Woo science

[Valacosa]

You're half right. I had forgotten about the quantum properties of transistors.

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!

Re:

[grrrgrrr]

So that is meant by a quantum computer . But i have to ask you a question to see if i really understand. For example when I think of finite state machines as a model for computers a quantum computer like is a direct implementation of a non-deterministic state machine?

Re:

[jtheisen]

Or a deterministic turing machine and a non-deterministic turing machine.

If someone in the know could answer this question this would be greatly appreciated.

Re:

[infolib]

Maybe you should look into this really nice bunch of intros to quantum computing. [qubit.org] (Click on "Tutorials").

Re:

[cannonfodda]

I'm with you on this one. I think this is total pants.

For a start: "In a superconductor all of the "particles" that carry charge around can exist in the exact same state, so when you look at a whole lot of these particles (many trillions) it can be just like looking at only one (which is "very quantum mechanical")."

My quantum mechanics is pretty rusty but I think the exclusion principle still holds at low temperatures. I which case, this is complete rot.

Re:

[cnettel]

For fermions, yes. One point in models of (some) superconductors is a special pairing of electrons to form a boson-like structure. The common exclusion principle is just an idealized special case, not a general law for all wave functions. Ever heard of L.A.S.E.R.?

ACK

[Anonymous Coward]

As a physicist who had courses in Quantum Computation I had to vomit when I just read the Title Superconducting Quantum Computer.

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

Quantum computing's Best candidate??

[Magi77]

I was wondering which one is the best candidate for Quantum computing. -Metal (superconductor) based -Optical quantum computer

The guy is a *tad* optimistic

[Ancient_Hacker]

Seeing as nobody has been able to make even a 2-bit quantum adder, the guy is a bit optimistic that he will have a supercomputer in a year.

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.

[AWeishaupt]

From what has been described on the blog and website, i'm not convinced that what they're working on is much more than simply a superconducting RSFQ - Rapid Single Flux Quantum - chip, which although can concievably run at a breakneck speed compared to todays Silicon CPU's, is not a Quantum Computer in the normal sense. This thing isn't going to run Shor's Algorithm. Also, i'm surprised to notice that there are people here who still consider QCs as science fiction - they're not. Quantum Computing has been practical in the lab since the 90's - and, for example, composite numbers have been factorised in polynomial time. The challenge faced by QCT research groups around the world at present is mainly building the things with a large number of qubits, and still maintaining successful operation. With regards to solid state devices such as the Kane QC model, one of the approaches being investigated involves building multiple small QCs and interconnecting them via conventional microelectronics - perhaps SETs, RSFQs, spintronics or maybe even plain old silicon microelectronics - to create a useful, many-qubit, computer.

Re:

[khallow]

Quantum Computing has been practical in the lab since the 90's - and, for example, composite numbers have been factorised in polynomial time.

How many qubits are we talking here? Last I heard which was within the last couple of years, the Shor algorithm had been used on the number 15, ie, manipulated four qubits of information. I also seem to recall that the log time search algorithm had been tried on seven qubits or so. These are fairly recent. Since the size of the problem is so small, I wouldn't cons

Re:

[Schwarzchild]

Also, i'm surprised to notice that there are people here who still consider QCs as science fiction - they're not.

Apparently, there are Computer Scientists who still regard quantum computing as science fiction. Read a few quantum computing blogs if you don't believe this to be true.

Carl Sagan Said it Best

[deadline]

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.

Re:

[philipmather]

> "No one understands quantum mechanics" Speaking as an Engineer I spend most of my days making things "I don't understand" work. It's not always necessary you know, I mean I've got a very good idea of how a SI engine works but I'd still be calling out the breakdown service if my Volvo packed up on the way to work. The other thing to consider is that some of the problems that a quantum computer would work on have an easily checkable answer. The travelling salesman problem might be tricky to verify, but

Do they know what they are talking about?

[rufusdufus]

The linked article, and the company web site is very sparse on information. Is there any indication that this guy knows what he's talking about? I did find one 'fact' on their web site [dwavesys.com] that indicates that the answer may be no. Take a look at the last paragraph on the page:

Quantum computers can be used to get approximate solutions to large NP-complete optimization problems much more quickly than the best known methods running on any supercomputer.

I think this statement is incorrect [wikipedia.org]. My understanding concurs with what is written in the wiki article:

This dramatic advantage of quantum computers is currently known to exist for only those three problems: factoring, discrete logarithm, and quantum physics simulations. However, there is no proof that the advantage is real: an equally fast classical algorithm may still be discovered (though some consider this unlikely). There is one other problem where quantum computers have a smaller, though significant (quadratic) advantage. It is quantum database search, and can be solved by Grover's algorithm. In this case the advantage is provable. This establishes beyond doubt that (ideal) quantum computers are superior to classical computers.

and

BQP is suspected to be disjoint from NP-complete and a strict superset of P, but that is not known. Both integer factorization and discrete log are in BQP. Both of these problems are NP problems suspected to be outside BPP, and hence outside P. Both are suspected to not be NP-complete. There is a common misconception that quantum computers can solve NP-complete problems in polynomial time. That is not known to be true, and is generally suspected to be false.

it's hard :(

[snafu109]

I find the very notion of quantam computing so complex that just reading the article's title made my head explode. Luckily there was a quantam wormhole within my skull that reassembled my head and brain, with no side effects whatsoever!

I like stories.

Low power CPU vs enormous cooling costs??

[slackaddict]

FTA:

"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

QC Simulator Demo + little patch

[drkfdr]

I came across some simulator... http://www.senko-corp.co.jp/qcs/ [senko-corp.co.jp] patched SetModifiedFlag (MFC) so you can simulate own circuits 00018030: 8B 31 (old and new value) 00018031: 44 C0 00018032: 24 90 00018033: 04 90 "Nag"screens removal 000011A0: 6A C3 00001470: 6A C3 Note that these patches still don't allow to save to a file but it's at least something.

Under the hood?

[clang_jangle]

The summary is waaaaay off base, as there are no "under the hood" details (except to identify a single construction material). Also no real claim of quantum computing is made.

Financial expert wanted

[exp(pi*sqrt(163))]

This device won't work. I won't bother giving my reasons. Can someone tell me how I can convert this knowledge into some kind of bet on a market that will make me money? It seems I ought to be able to use this knowledge somehow.

You can't because.....

[citanon]

It's a private company.

Let me say that more clearly

[exp(pi*sqrt(163))]

Creative financial advisor sought.

MIT Technology Review Article on DWave

[citanon]

[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

Re:

[citanon]

No, it's saying that it doesn't need anything exotic. The beauty of their system, if it works, is its simplicity. They've found the simplest iteration of the "quantum computer" that's still useful for real world applications. I hope that they succeed. It would be nice to finally get some accurate energies for quantum chemistry systems where electron correlation is important. Right now, we can't even calculate van der waals forces ab initio.

typo

[torvince]

''It is based on nobium superconducting 'circuits of atoms'''

I dont know what nobium is, i hoped it was based on niobium ...

That kind of hood must be very small

[eille-la]

It is all in the title

I guess Josephson junctions and/or vaporware

[infolib]

This smells vaguely like vaporware. At least none of the speakers at this years or last years Spin and Qubit conference [isis.ku.dk] seemed nearly as optimistic as these guys, even though there were several top notch people (and last year the focus was VERY much quantum computing).

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

[infolib]

They've put up a paper on their techniques [arxiv.org]. And judging from the pictures, they do something that looks like serious research [mitstanfor...eynano.org]. Interesting. Apparently they're after quantum chemical computations.

Quantum computers...eh

[InterestingX]

When they come up with a quantum torpedo, I'll listen...

I would be surprised it they manage....

[drolli]

to build a working Quantum Computer until 2007. It would be a nice surprise, actually....

As a small disclaimer: I work in QC field. There are a few approaches to building a superconducting quantum computer, but there are not many experiments coupling even two Qubits. One paper discussing one of the few experiments which worked is:

http://scholar.google.com/scholar?q=author:%22Pash kin%22%20intitle:%22Quantum%20oscillations%20in%20 two%20coupled%20charge%20qubits%22%20&hl=de&hs=oKY &lr=&safe=o [google.com]

Under the hood?

[Mr. Bad Example]

I opened the hood of my quantum computer, and all I found was a cat and some guy who kept asking for Wigner. I'm thinking of getting my money back.

Re:

[gweihir]

What a load of rubbish. Quantum computinf is nowhere near the level where it is useful for anything, let alone for building a supercomputer out of it.

While I completely agree, it seems enough to get funding. A sad state of affairs, indeed.

Re:

[Anonymous Coward]

What would be the point of funding something already useful? Things are funded on the basis of their potential, not on what they can do now.

Re:

[gweihir]

What would be the point of funding something already useful? Things are funded on the basis of their potential, not on what they can do now.

True. But this has zero potential. So it should not be funded.

Re:

[biz0r]

Funny you say that, some [monash.edu.au] people [wikipedia.org] think [valdostamuseum.org] that is already the case. Who'da thunk it...

As someone somewhat affiliated...

[PaulBu]

... I can say definitely, YES!

Paul B.