Under the Hood of Quantum Computing 156
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)."
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.
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
Re:"Quantum" computer is misleading (Score:5, Informative)
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.
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:
It just sounds a lot like a RSFQ chip. (Score:4, Informative)
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 of the approaches discussed today). The larges stable aray of qubits is 8 AFAIK, and you cannot do anything with those so far everybody is just working on stbility and prooves of concept.
1) Hence there is no usefull quantum computer in existence. Anyone who want's to sell you one is a liar.
Superconductivity, is well known and not very hard to achieve. I can make pretty much any material superconducting if you just give me a liquid Helium 3/4 demixer. So once I have a working quantum computer, I can add some lead, empty a bottle of Liquid Helium over it, and claim, that I have a super conducting Quantum computer. To be fair it's often inherent in the design of a Quantum computer that it needs to be very cold. But it doesn't always need to be so. But what remains is
2) Saying a quantum computer is superconducting doesn't add any infomation about the usefullness of such a device.
So what could this headline mean:
Someone allows you to use his NMR (Nuclear Magnetic Resonance) device if you give him money.
(NMR is standard in todays chemistry labs, and very simple useless quantum algorithms (see "Deutsch algorithm") have been implemented with it.)
Where is the beef? Can an article still be kicked out at this stage?
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.
QP =? NP (Score:3, Informative)
Re:Advantages? (Score:5, Informative)
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.
Complete nonsense (Score:1, Informative)
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
Re:Woo Woo science (Score:3, Informative)
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?
I would be surprised it they manage.... (Score:2, Informative)
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:%22Pas
But there are severe problems with superconducting qubits, namely that the quality of the insulators used in standard processes are not good enough for building a working QC right now.
(http://eiffel.ps.uci.edu/cyu/publications/qubit.
http://link.aps.org/doi/10.1103/PhysRevLett.95.21
It's not that these fundamental problems could not be adressed by developing better insulators or using other approaches
(http://www.solid.phys.ethz.ch/wallraff/content/s
But indeed, superconductors are one of the best candidates (others: atom traps etc.).
The role of D-Wave is that they are trying to push the development of superconducting QC to something which can be sold or where at least the patents can be sold. So it is natural (and probably good) that the external represantation on what they got is optimistic. But maybe it is important to point out to the slashdot readers that the blog of the CEO of a company is for sure an optimistic assumption what the future may hold and not the full criticism imposed by a peer-review in a scientific journal........
Another thing which makes it difficult to assess what they got is that D-Wave is usually pretty uninformative about what their specific plans are. Thats understandable because they spend a lot of money (for a company) into something where they will get out patents which would be weakened by prior art if they talk to loud.
"like getting two qubits to interact..." (Score:3, Informative)
Paul B.
Re:I think it will. (Score:3, Informative)
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 O(N) to O(N^0.5). That alone is enough to put AES-128 in range of today's horsepower (but not enough to reach AES-256). Maybe it's provably impossible to reduce symmetric decryption to less than linear search, I don't know.
The number of plausible-but-wrong decryptions of a cipher block you know the plaintext for is zero, so unicity distance is only trivially relevant; if you insist, we can say it's exactly the cipher block size regardless of the plaintext language in this specific case.
Re:Advantages? (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 as you don't look.
Before you think this is all hogwash, quantum mechanics is actually one of most successful theories that physics has ever proposed.