Thursday, January 11, 2007
Some notes on D-Wave Orion
But to tell the truth, I really doubt how accurate D-wave behave like a true quantum machine. Below are some notes I found on the web. It is a pitty that I cannot connect to http://dwave.wordpress.com/ or http://www.scottaaronson.com/ (totally do not know why).
benleidawang (本垒打王) 于 (Sun Feb 18 19:06:17 2007) 提到:
发信人: draculalord ( 嗯？), 信区: SF
标 题: Re: 全球首台商用量子计算机将在下周展示 (转载)
发信站: 水木社区 (Tue Feb 13 03:46:10 2007), 站内
Grudgingly offered for your reading pleasure, and in the vain hope of forest
alling further questions.
Q: Thanks to D-Wave Systems — a startup company that’s been in the news la
tely for its soon-to-be-unveiled “Orion” quantum computer — is humanity n
ow on the verge of being able to solve NP-complete problems in polynomial ti
A: No. We’re also not on the verge of being able to build perpetual-motion
machines or travel faster than light.
Q: But couldn’t quantum computers try all possible solutions in parallel, a
nd thereby solve NP-complete problems in a heartbeat?
A: Yes, if the heart in question was beating exponentially slowly.
Otherwise, no. Contrary to widespread misconception, a quantum computer coul
d not “try all possible solutions in parallel” in the sense most people me
an by this. In particular, while quantum computers would apparently provide
dramatic speedups for a few “structured” problems (such as factoring integ
ers and simulating physical systems), it’s conjectured that they couldn’t
solve NP-complete problems in polynomial time.
Q: But isn’t factoring an NP-complete problem?
A: Good heavens, no! While factoring is believed to be intractable for class
ical computers, it’s not NP-complete, unless some exceedingly unlikely thin
gs happen in complexity theory. Where did you get the idea that factoring wa
s NP-complete? (Now I know how Richard Dawkins must feel when someone asks h
im to explain, again, how “life could have arisen by chance.”)
Q: How could the people at D-Wave not understand that quantum computers coul
dn’t solve NP-complete problems in polynomial time?
A: To his credit, Geordie Rose (the founder of D-Wave) does understand this;
see here for example. And yet, essentially every article I’ve read about D
-Wave gives readers exactly the opposite impression. The charitable explanat
ion is that the D-Wave folks are being selectively quoted or misquoted by jo
urnalists seeking to out-doofus one another. If so, one hopes that D-Wave wi
ll try harder in the future to avoid misunderstandings.
Q: But even if it gave only polynomial speedups (as opposed to exponential o
nes), couldn’t the adiabatic quantum computer that D-Wave built still be us
eful for industrial optimization problems?
A: D-Wave’s current machine is said to have sixteen qubits. Even assuming i
t worked perfectly, with no decoherence or error, a sixteen-qubit quantum co
mputer would be about as useful for industrial optimization problems as a ro
Q: But even if it wasn’t practically useful, wouldn’t a 16-qubit supercond
ucting quantum computer still be a major scientific advance?
A: Yes, absolutely.
Q: So, can D-Wave be said to have achieved that goal?
A: As Dave Bacon pointed out earlier, it’s impossible to answer that questi
on without knowing more about how their machine works. With sixteen qubits,
a “working demo” doesn’t prove anything. The real questions are: how high
are the fidelities, and what are the prospects for scalability?
Q: But clearly D-Wave isn’t going to give away its precious trade secrets j
ust to satisfy some niggling academics! Short of providing technical specifi
cs, what else could they do to make computer scientists take them seriously?
A: Produce the prime factors of
Q: Alright, what else could they do?
A: Avoid talking like this:
The system we are currently deploying, which we call Trinity, is a capabilit
y-class supercomputer specifically designed to provide extremely rapid and a
ccurate approximate answers to arbitrarily large NP-complete problems … Tri
nity has a front-end software interface, implemented in a combination of Jav
a and C, that allows a user to easily state any NP-complete problem of inter
est. After such a problem has been stated the problem is compiled down to th
e machine language of the processors at the heart of the machine. These proc
essors then provide an answer, which is shuttled back to the front end and p
rovided to the user. This capability can of course be called remotely and/or
as a subroutine of some other piece of software.
Or to translate: “Not only have we built a spaceship capable of reaching Pl
uto in a few hours, our spaceship also has tinted windows and deluxe leather
seats!” If I were them, I’d focus more on the evidence for their core tec
hnological claims, given that those claims are very much what’s at issue.
Q: While Dave Bacon also expressed serious doubts about the Orion quantum co
mputer, he seemed more enthusiastic than you are. Why?
A: Generous and optimistic by nature, Dave strives to give others the benefi
t of the doubt (as the Chinese restaurant placemat would put it). Furthermor
e, as Quantum Pontiff, he’s professionally obligated to love the quantum si
nner and forgive the wayward quantum sheep. And these are all wonderful qual
ities to have. On the other hand, when the hype surrounding some topic cross
es a certain threshold, arguably a pricklier approach becomes called for.
Q: If D-Wave fizzles out, will many journalists and policymakers then conclu
de that quantum computing is bunk?
A: It doesn’t seem unlikely.
Q: What would it take to get these people to recognize the most elementary d
A: That’s the question, isn’t it?
This entry was posted on Friday, February 9th, 2007 at 9:34 am and is filed
under Quantum, Rage Against Doofosity. You can follow any responses to this
entry through the RSS 2.0 feed. You can leave a response, or trackback from
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※ 来源:·水木社区 newsmth.net·[FROM: 147.83.49.*]
Krank (娉娉袅袅十三馀，豆蔻梢头二月初) 于 (Sat Feb 17 20:31:07 2007) 提到:
Krank (娉娉袅袅十三馀，豆蔻梢头二月初) 于 (Mon Feb 19 00:55:16 2007) 提到:
Because Orion must be kept refrigerated and isolated from outside influences
that could disrupt its computations, the company only remotely accessed the
system in its demonstration. Likewise, D-Wave hasn't proven Orion's exact n
ature to the scientific community, but may release details for scientific pe
er review. At that point, scientists can argue over the finer points of quan
tum mechanics and if Orion is truly a "quantum computer."
Krank (娉娉袅袅十三馀，豆蔻梢头二月初) 于 (Mon Feb 19 01:01:05 2007) 提到:
And notwithstanding lofty claims in the company's press release about creati
ng the world's first commercial quantum computer, D-Wave Chief Executive Her
b Martin emphasized that the machine is not a true quantum computer and is i
nstead a kind of special-purpose machine that uses some quantum mechanics to
"Users don't care about quantum computing - users care about application acc
eleration. That's our thrust," he said. "A general purpose quantum computer
is a waste of time. You could spend hundreds of billions of dollars on it" a
nd not create a working computer.
He said all the evidence the company has indicates that the device is perfor
ming quantum computations, but he acknowledged there is some uncertainty. He
also said the company could encounter problems in maintaining quantum funct
ions as the machine is made more powerful.
Krank (娉娉袅袅十三馀，豆蔻梢头二月初) 于 (Mon Feb 19 20:40:42 2007) 提到:
benleidawang (本垒打王) 于 (Thu Feb 22 21:54:30 2007) 提到:
Puzzle-solving quantum computer is unveiled
A Canadian firm has revealed what it claims is the first fully functioning quantum computer — generating both interest and scepticism from physicists.
D-Wave Systems, based in Burnaby, British Columbia, debuted its system on 13 February at the Computer History Museum in Mountain View, California. The computer used its 16 quantum bits, or qubits, to match proteins in a database, create a seating chart for a wedding party and solve a sudoku puzzle.
Critics say that the machine, which takes an unusual approach known as 'adiabatic quantum computing', may not be performing strictly quantum-mechanical computations. The adiabitic technique leaves the machine to conduct quantum computations on its own, making it difficult to tell whether it is behaving in a quantum or a classical manner.
"I'm really very sceptical," says Umesh Vazirani, a computer scientist at the University of California, Berkeley, adding that he would like to see more data before he is convinced.
benleidawang (本垒打王) 于 (Thu Feb 22 22:00:28 2007) 提到:
Physics Today Favorite 上转的报道
The Father of Quantum Computing
Does quantum computing have a future?
On Tuesday, Canadian company D-Wave Systems demonstrated a 16-qubit, specific-purpose quantum computer to a room packed with observers and thick with doubt and awe. Reporters watched as the machine solved a Sudoku puzzle and a seating arrangements problem, and, most impressively, searched for molecules similar to the drug Prilosec from a database of molecules.
But the final significance of D-Wave's demo is as uncertain as the fate of Schrödinger's cat -- opinions are all over the place, within the scientific community and without. To cut through the fog, Wired News sought out the father of quantum computing, Oxford University theoretical physicist David Deutsch.
Deutsch invented the idea of the quantum computer in the 1970s as a way to experimentally test the "Many Universes Theory" of quantum physics -- the idea that when a particle changes, it changes into all possible forms, across multiple universes.
Deutsch is a leading proponent of the theory, so, while he wasn't in attendance at the D-Wave announcement, perhaps it's safe to say as well that he was. Wired News pulled him away from dinner to talk about what a quantum computer really is, what it's good for and what D-Wave's announcement might mean for the future.
Wired News: D-Wave announced 16 qubits, and they want people to play with them, so they're talking about having a web API where people can try to port their own applications and see how it works. Do you think that's a good approach to gaining some acceptability and mind share for the idea of quantum computing?
David Deutsch: I think the field doesn't need acceptability. The idea will either be valid, or not. The claim will either be true, or not. I think that the normal processes of scientific criticism, peer review and just general discussion in the scientific community is going to test this idea -- provided enough information is given of what this idea is. That will be quite independent of what kind of access they provide to the public.
However, I think the idea of providing an interface such as you describe is a very good one. I think it's a wonderful idea....
WN: Can you give a couple of examples of what kind of things can be done with quantum computing that either can't be done, or can't be done practically, with classical computing?
Deutsch: The most important application of quantum computing in the future is likely to be a computer simulation of quantum systems, because that's an application where we know for sure that quantum systems in general cannot be efficiently simulated on a classical computer. This is an application where the quantum computer is ideally suited.
Perhaps in the long run, as nanotechnology becomes quantum technology, that will be a very important generic application.
Another thing I should say is, that application is the only one of the major applications -- apart from quantum cryptography, by the way, which is already implemented and is really in a different category -- that might be amenable to a non-general purpose quantum computer. That is to say, a special-purpose quantum computer.
WN: Can you talk a little about the importance of simulating quantum systems, and give an example?
Deutsch: Yes. Whenever we design a complex piece of technology we need to simulate it, either in theory by working out the equations that govern it, or as a computer simulation, by running a program on the computer whose motion mimics that of the real system.
But when we come to designing quantum systems, we're going to have to simulate the behavior of quantum super positions, which is, in Many Universes terms, when an object is doing different things in different universes. On a classical computer you'd have to work out what every single one of those was, and then combine them in the end with the equations governing quantum interference.
WN: And that becomes computationally impossible?
Deutsch: That becomes infeasible very, very quickly, once you've got more than three, four, five particles involved, whereas a quantum computer could mimic such a process directly by itself doing that number of computations simultaneously in different universes. So it is naturally adapted to that kind of simulation, if we wanted to work out, let's say, the exactly properties of a given molecule.
Some people have suggested this might be useful for designing new drugs, but we don't know if that's the case or not. Although quantum processes are needed in general for atomic and molecular scale properties, not all of them (need quantum processes). An example of that is we've been able to do a lot of biotechnology without having any quantum simulators.
WN: Do you think a quantum computer could eventually build a slightly more macro simulation, something like an immune system, in order to see how it interacts with a drug?
Deutsch: No, that's not what it would be used for. It would be used for smaller things, not things on a larger scale than a molecule, but things on a smaller scale. Small molecules and interactions within an atom, subtle differences between different isotopes, that sort of thing. And of course things on an even smaller scale than that. Nuclear physics, and also artificial, atomic-sized things which will be used in nanotechnology.
Of which at the moment the only ones planned are quantum computers. Of course quantum computer designing other quantum computers is undoubtedly going to be one of the applications.
WN: The other field I can see ... this revolutionizing is materials science.
Deutsch: Yes, yes. Again we don't know how revolutionary it will be, but certainly on the small scale, it will be indispensable.
WN: What would you like to see the field trying to do?
Deutsch: I'm probably the wrong person to ask that because my own interest in this field is not really technological. To me quantum computation is a new and deeper and better way to understand the laws of physics, and hence understanding physical reality as a whole. We are really only scratching the surface of what it is telling us about the nature of the laws of physics. That's the kind of direction that I'm pursuing.
The pleasant thing about that is that can be done before one even makes a quantum computer. The theoretical conclusions are already there, and we can work on them already. It's not that I don't think technological applications are important, but I watch them as an eager spectator rather than participant.
WN: For your purposes, the importance of quantum computing is in the general case more than in the specific-use case.
Deutsch: Yes. The fact that the laws of physics permit themselves to be simulated by a quantum computer is a deep fact about the nature of the universe that we will have to understand more deeply in the future.
WN: How do you think using quantum computers will change how people think about computing, and consequently the universe and nature?
Deutsch: "How they will think about it" is the relevant phrase here. This is a philosophical and psychological question you're asking. You're not asking a question about the physics or the logic of the situation.
I think that when universal quantum computers are finally achieved technologically, and when they are routinely performing computations where there is simply more going on there than a classical computer or even the whole universe acting as a computer could possibly achieve, then people will get very impatient and bored, I think, with attempts to say that those computations don't really happen, and that the equations of quantum mechanics are merely ways of expressing what the answer would be but not how it was obtained.
The programmers will know perfectly well how it was obtained, and they will have programmed the steps that will have obtained it. The fact that answers are obtained from a quantum computer that couldn't be obtained any other way will make people take seriously that the process that obtained them was objectively real.
Nothing more than that is needed to lead to the conclusion that there are parallel universes, because that is specifically how quantum computers work.
WN: So what prompted you to start thinking about quantum computing?
Deutsch: This goes back a long way before I even thought of general purpose quantum computing. I was thinking about the relationship between computing and physics.... This was back in the 1970s....
It had been said, ever since the parallel universes theory had been invented by Everett in the 1950s, that there's no experimental difference between it and the various (theories), like the Copenhagen interpretation, that try to deny that all but one of the universes exist.
Although it had been taken for granted that there was no experimental difference, in fact, there is -- provided the observer can be analyzed as part of the quantum system. But you can only do that if the observer is implemented on quantum hardware, so I postulated this quantum hardware that was running an artificial intelligence program, and as a result was able to concoct an experiment which would give one output from an observer's point of view if the parallel universes theory was true, and a different outcome if only a single universe existed.
This device that I postulated is what we would now call a quantum computer, but because I wasn't particularly thinking about computers, I didn't call it that, and I didn't really start thinking about quantum computation as a process until several years later. That lead to my suggesting the universal quantum computer and proving its properties in the mid-'80s.
WN: How many qubits (does it take) to make the general-purpose quantum computer useful?
Deutsch: I think the watershed moment with quantum computer technology will be when a quantum computer -- a universal quantum computer -- exceeds about 100 to 200 qubits.
Now when I say qubits, I have to stress that the term qubit hasn't got a very precise definition at the moment, and I've been arguing for a long time that the physics community ought to get together and decide on some criteria for different senses for the word qubit. What I mean here is a qubit which is capable of being in any quantum state, and is capable of undergoing any kind of entanglement with another qubit of the same technology, and all those conditions are actually necessary to make a fully fledged quantum computer.
If you relax any one of the those conditions it's much easier to implement in physics. For instance, if you call something a qubit but it can only be entangled with qubits of a different technology, then it's much easier to build. But of course a thing like that can't be made part of a computer memory. (With) computer memory you need lots of identical ones.
There's also the question of error correction. The one physical qubit is probably not enough to act as a qubit in genuine quantum computation, because of the problem of errors and decoherence. So you need to implement quantum error correction, and quantum error correction is going to require several physical qubits for every logical qubit of the computer. When I said you need 100 to 200, that probably means several hundred, or perhaps 1,000 or more, physical qubits.
WN: To get an effective 100 or 200 qubits.
Deutsch: Yes, and that is what would have to count as the watershed for quantum computation, for being a distinctive new technology with its own genuine uses.
WN: That's actually D-Wave's stated goal as well: essentially 1,000 qubits in two years. Do you think engineering-wise, and this is not completely within your realm, they will be able to maintain enough coherence at that level to create a practical computer.
Deutsch: As you said that really isn't my field. Maintaining coherence itself isn't quite enough. They've got to maintain coherence in the operation that I spoke of; that is, the arbitrary superposition, the arbitrary entanglement, and so on....
I don't know. The technologies I've seen so far have got way fewer than 1,000. They've got way fewer than 16. I always have to ask whether the claimed number of qubits are qubits that I would count as qubits by these stringent criteria, or whether it's merely two-state systems that can in some sense act in a quantum way. Because that's a much more lenient criterion.
WN: I don't have the sophistication to answer that, for D-Wave at least. If I were to ask you to cast your mind forward, saying everything goes well, what does a world that combines ubiquitous quantum computing and classical computing look like? And you've said that quantum computing would never replace classical computing.
Deutsch: It's not anywhere near as big a revolution as, say, the internet, or the introduction of computers in the first place. The practical application, from a ordinary consumer's point of view, are just quantitative.
One field that will be revolutionized is cryptography. All, or nearly all, existing cryptographic systems will be rendered insecure, and even retrospectively insecure, in that messages sent today, if somebody keeps them, will be possible to decipher ... with a quantum computer as soon as one is built.
Most fields won't be revolutionized in that way.
Fortunately, the already existing technology of quantum cryptography is not only more secure than any existing classical system, but it's invulnerable to attack by a quantum computer. Anyone who cares sufficiently much about security ought to be instituting quantum cryptography wherever it's technically feasible.
Apart from that, as I said, mathematical operations will become easier. Algorithmic search is the most important one, I think. Computers will become a little bit faster, especially in certain applications. Simulating quantum systems will become important because quantum technology will become important generally, in the form of nanotechnology.
WN: If we have practical nanotechnology, I imagine that's a huge change.
Deutsch: Nanotechnology has the potential of making a huge change. But the only involvement of quantum computers is that it will make it easier to design nanotechnological devices. Apart from that I don't think it's a big technological revolution.
What it is though, philosophically, is taking a quantum world view. That is rather a revolution, but that could happen today and the only reason it has been sluggish in happening is psychological, and maybe quantum computers will help with this psychological process. That's a very indirect phenomenon.
WN: It does allow people to play with it, and they often get things better when they play with them.
Deutsch: That's true.
WN: I wanted to ask you to describe your book a bit.
Deutsch: You'll remember I said for me the most important thing about quantum computation is the way it shows us the deep connections between physics on the one hand and computation on the other, which were previously suspected by only a few pioneers like Rolf Landauer of IBM.
My book (The Fabric of Reality) is about this connection between computation and fundamental physics, between those two apparently unconnected fields.... To me, (that connection is) part of a wider thing, where there are also two other strands, the theory of knowledge and the theory of evolution.
The Fabric of Reality is my attempt to say that a world view formed out of those four strands is the deepest knowledge that we currently have about the world.
benleidawang (本垒打王) 于 (Sat Feb 24 15:28:17 2007) 提到:
D-Wave Systems got $17.5 mln from Draper Fisher Jurvetson to work on a preliminary version of a quantum computer
4.第4篇是说D-wave在2006年5月有了一个新的CEO Herbert J. Martin，有人对他的评价还不错。
Quantum Computer to be Ready in Three Years
by Dave Murphy
D-Wave Systems, a Vancouver-based computer engineering firm has announced it's schedule to build a working quantum computer that will be able to solve physical-simulation problems that currently aren't solvable using available processing tools. The computer is to be ready within three years. While most designs for quantum computers focus on the properties of quantum entanglement to calculate binary functions, the D-Wave system will use quantum tunneling, which enables particles to hop from one location to another without traversing the intervening space.
D-Wave's design takes advantage of an low-temperature superconducting analog chip, rather than the sensitive lasers and vacuum tools required by other quantum computer designs.
For those of you who are long-time ITrain subscribers, you know that I've had an interest in the development of quantum computing tools for more than two decades. I'm excited about D-Wave's design, and I have to admit, I'm heartened by the company's ability to break ranks and look to an alternative design that may facilitate the early adoption of quantum computing technology.
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A Working Quantum Computer in 3 Years?
Posted by timothy on Wed Jun 22, '05 05:02 AM
06.22.05 @ 03:50 PM ET
Copyright © 2005 Damar Group, Ltd., All Rights Reserved
Vancouver, BC-based D-Wave Systems got $17.5 mln from Draper Fisher Jurvetson to work on a preliminary version of a quantum computer, Technology Review reports. Delivery date? 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.'"
D-Wave says they'll have a quantum computer ready by 2008
Posted Jun 23rd 2005 11:42AM by Thomas Ricker
Filed under: Misc. Gadgets
If you think about it, a computer only needs to measure the change of state to, well, compute — be it ones and zeros or the state of subatomic particles. That's why there is such interest in the development of the mythical quantum computer (think supercomputer in a teaspoon). For the most part, efforts in quantum computer development have focused on a property called entanglement. But Vancouver startup D-Wave is focusing on quantum tunneling instead and hope to exploit this to develop a quantum computer within three-years (with a prototype by close of 2006). At the heart of their "less than fully functional" quantum computer is an analogue chip which must be cooled with liquid helium to -269 °C — just 4 °C shy of absolute zero folks! However, these purpose-built semiconductors rely on existing fabrication techniques and do not need the gee-whiz guts (delicate lasers, vacuum pumps) required by other quantum computers. While cryptographers will have to wait for their dream machine, intractable problems such as the infamous traveling-salesman (optimal route among cities) and optimization of financial portfolios and traditional computer chip layouts could be quickly sorted. Don't bother raiding the kid's college fund yet 'cause D-Wave expects to sell computational services not quantum hardware
May 9, 2006 on 6:27 pm | In Quantum, Computation |
D-Wave Systems, those crazy Vancouverites trying to build a quantum computer, have a new CEO:
VANCOUVER, BRITISH COLUMBIA, May 9 /CNW/ - D-Wave, developer of the world’s most advanced computers, has appointed Silicon Valley technology executive and entrepreneur Herbert J. Martin as chief executive officer.
Which makes me dream of the day when I will be able to include in my grant proposal a request for dollars to buy a quantum computer.
1. It’s a good sign. Herb is a top caliber CEO. Someone with his experience, background and success rate wouldn’t join the company if the technology wasn’t already working. Building working machines is necessary but not sufficient to build a successful business. History is littered with cool technologies that have failed in the marketplace.
Comment by Geordie — 5/12/2006