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Separating Hope From Hype In Quantum Computing
pgptag writes "This talk by Dr. Suzanne Gilbert (video) explains why quantum computers are useful, and also dispels some of the myths about what they can and cannot do. It addresses some of the practical ways in which we can build quantum computers and gives realistic timescales for how far away commercially useful systems might be."
Upon observation, this post has collapsed into the first post state.
Oops. Thought this thread title was about Obama....sorrry.
We can't even get people to read the articles referenced in submissions. That's wildly optimistic to expect us to watch a video that is over 2 hours long.
This is begging for an "executive summary" from anyone who has time to watch it, if there is such a person.
Is that on the iPad or iPod Touch? :)
The quantum computer is both a realistic ideal and vaporware hype, until a computer journalist examines the claims.
Definitely commercial-only. The world only needs five quantum computers.
Maybe in the future, a Quantum Computer running Windows x.x will be able to harness its power to show the contents of a folder in less than the 30 seconds it takes now.
When Fascism comes to America, it will call itself Anti-Fascism, and tell you to give up your guns.
Someone from D-wave is giving a talk called "separating hope from hype": http://arstechnica.com/hardware/news/2007/02/quantum.ars http://www.technologyreview.com/computing/20587/ http://en.wikipedia.org/wiki/D-Wave_Systems
It appears that the moderators don't know any history. You're obviously making a joke based on the observation in the early 1950s that "the worldwide market for computers is about ten." It's funny now, but then computers weren't very useful for anybody without huge number crunching and database needs and multi-million dollar budgets. At the time, a computer took an entire building to house, and a whole lot of personnel to operate. The most powerful computer in existance was less powerful than a singing Hallmark card.
So the joke's on the mods, who actualy believe it. Of course, right now the worldwide market is zero, since they haven't actually constructed one yet. If and when they accomplish the feat, it's possible that in the future all compuers will be quantum computers. I doubt I'll live long enough to see it (I'm not young any more).
That link will give the mods a little computer history if they're interested.
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I was going to listen, but the dude yakking in the background totally oblivious (well..not totally oblivious as he questioned himself as to why he can hear himself talking) to the fact that his mic is broadcasting right over the speaker. Dumb.
I took a class on Quantum computing, and studied many specific QC algorithms, so I know a little bit about them. If you don't want to RTFA, then read this: Quantum Computers are not super-computers. On a bit-for-bit (or qubit-for-qubit) scale, they're not necessarily faster than regular computers, they just process info differently. Since information is stored in a quantum "superposition" of states, as opposed to a deterministic state like regular computers, the qubits exhibit quantum interference around other qubits. Typically, your bit starts in 50% '0' and 50% '1', and thus when you measure it, you get a 50% chance of it being one or the other (and then it assumes that state). But if you don't measure, and push it through quantum circuits allowing them to interact with other qubits, you get the quantum phases to interfere and cancel out. If you are damned smart (as I realized you have to be, to design QC algorithms), you can figure out creative ways to encode your problem into qubits, and use the interference to cancel out the information you don't want, and leave the information you do want. For instance, some calculations will start with the 50/50 qubit above, and end with 99% '0' and 1% '1' at the end of the calculation, or vice versa, depending on the answer. Then you've got a 99% chance of getting the right answer. If you run the calculation twice, you have a 99.99% chance of measuring the correct answer. However, the details of these circuits which perform quantum algorithms are extremely non-intuitive to most people, even those who study it. I found it to require an amazing degree of creativity, to figure out how to combine qubits to take advantage of quantum interference constructively. But what does this get us? Well it turns out that quantum computers can run anything a classical computer can do, and such algorithms can be written identically if you really wanted to, but doing so gets the same results as the classical computer (i.e. same order of growth). But, the smart people who have been publishing papers about this for the past 20 years have been finding new ways to combine qubits, to take advantage of nature of certain problems (usually deep, pure-math concepts), to achieve better orders of growth than possible on a classical computer. For instance, factoring large numbers is difficult on classical computers, which is why RSA/PGP/GPG/PKI/SSL is secure. It's order of growth is e^( n^(1/3) ). It's not quite exponential, but it's still prohibitive. It turns out that Shor figured out how to get it to n^2 on a quantum computer (which is the same order of growth as decrypting with the private key on a classical computer!). Strangely, trying to guess someone's encryption key, normally O(n) on classical computers (where n is the number of possible keys encryption keys) it's only O(sqrt(n)) on QCs. Weird (but sqrt(n) is still usually too big). There's a vast number of other problems for which efficient quantum algorithms have been found. Unfortunately, a lot of these problems aren't particularly useful in real life (besides to the curious pure-mathematician). A lot of them are better, but not phenomenal. Like verifying that two sparse matrices were mulitplied correctly has order of growth n^(7/3) on a classical computer, n^(5/3) on a quantum computer. You can find a pretty extensive list by googling "quantum algorithm zoo." Unfortunately [for humanity], there is no evidence yet that quantum computers will solve NP-complete problems efficiently. Most likely, they won't. So don't get your hopes up about solving the traveling salesmen problem any time soon. But there is still a lot of cool stuff we can do with them. In fact, the theory is so far ahead of the technology, that we're anxiously waiting for breakthroughs like this, so we can start plugging problems through known algorithms.
That is obviously not the only thing it can do. In P time it can solve P problem (much like a classical computer, but potentially using $\sqrt{classical}$ time, if it meets the above requirements. You can use quantum computing to find (with any probability of your choice which is less than one) the solution to a BPP problem in P time, which is again just like classical computers. Something new here is the ability to solve BQP problems (with any chosen probality less than one) in P time.
That last one is the killer. That is because two of the "hard" problems we use in asymmetric cryptography are BQP, namely integer factroization and discrete logarithms
are in BQP.[1]
What we really want is asymmetric encryption based on an NP-complete problem where many instances can be shown to take no less time (asymptotically) than the hardest instances to solve (i.e. many instances are tied for the hardest), and an easy way to generate instances of this hardest problem, and corresponding solution. That is really tricky, as many FNP problems that are not optimization problems (not NPO) have many instances that can be solved in only P time.
Footnote:
[1] Actually that is not strictly true. The problems have more than a yes or no answer, making them FBQP problems. But FBQP-complete problems take no longer to solve than BQP-complete problems. So quantum computers can solve FBQP with any given probability of success in only P time.
Stylish sheet to fix many problems in Slashdot's D3: https://gist.github.com/801524
The quote debunked http://en.wikipedia.org/wiki/Thomas_J._Watson#Famous_misquote
Some facts:
1) The misquote is "I think there is a world market for maybe five computers,"
2) The story had already been described as a myth in 1973
3) Correct quote: "IBM had developed a paper plan for such a machine and took this paper plan across the country to some 20 concerns that we thought could use such a machine. [...] But, as a result of our trip, on which we expected to get orders for five machines, we came home with orders for 18."
Don't fight for your country, if your country does not fight for you.
Geez, thanks for ruining a good meme with facts. Next thing you know we'll find out all those cats have been misquoted time and time again.
Random Thoughts From A Diseased Mind (Not For Dummies)
These crooks from D-Wave just won't give up. 128 qubits quantum computer!? pics or it didn't happen.
For more info: http://en.wikipedia.org/wiki/D-Wave_Systems
entropy happens
Actually, based on TFA, I'd say we're more likely to see a multi-core processor with some quantum and some classic cores. Kind of like the old floating point co-processors, or going back still further, the TI-99/4A architecture which was made up of a CPU with dedicated video, audio, and peripheral co-processors.
SJW: a person who perceives an injustice, and while correcting it, commits a greater injustice.