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Light-based Quantum Circuit Does Basic Maths
Posted by
Zonk
on Fri Dec 14, 2007 04:04 PM
from the small-steps-start-small dept.
from the small-steps-start-small dept.
Stochastism writes "In yet another small step toward realistic quantum computing Australian researchers have developed a light based 4-qubit quantum computer. It has already calculated the prime roots of fifteen, three and five. 'The quantum circuit pioneered by the Queensland researchers involves using a laser to send "entangled" photons through a linear optical circuit ... The Queensland research group acknowledged that the theorised code cracking ability of quantum computers may be why Australian quantum computer research is in part funded by a US government defence intelligence agency, the Defense Advanced Research Projects Agency (DARPA).'"
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How many maths does it do? (Score:4, Funny)
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one quick reference here [suite101.com]
There are various accepted abbreviations for the word mathematics, and one is as good as any other. In Germany, the abbreviation is "Mathe," in Britain and Canada, it is "maths," and in the USA, it is "math."
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But... (Score:5, Funny)
having trouble with the conversion (Score:2, Funny)
4 qubits? How much is that in furlongs?
hectares?
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Re:having trouble with the conversion (Score:5, Funny)
Until that point a cubit represents a dead cat.
Parent
Re:having trouble with the conversion (Score:5, Funny)
Schrödinger's Cat
Dead or Alive
Parent
Correction (Score:5, Funny)
Schrödinger's Cat
Dead and Alive
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Wikipedia: Qubit [wikipedia.org]
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Moore's law (Score:3, Funny)
Re:Moore's law (Score:5, Funny)
-moderatorrater, 2007
Parent
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Err (Score:3, Interesting)
Of course, the article doesn't help.
Anyone?
Re:Err (Score:5, Informative)
Typically with photons, it consists of the direction of polarization of the electro-magnetic field associated with the photon. Straight up and down represents one state, horizontal represents the the second state, and the photon can be in a superposition of both of these states.
Saying that photons get "destroyed" is irrelevant so long as we can measure the photon's polarization when it gets destroyed because as soon as we measure the polarization, the quantum state of the photon is destroyed anyway and becomes worthless to us. This is true of any quantum mechanical system, so whether the system representing the qubit sticks around or disappears after being measured (whether a photon, electron spin, or otherwise), is only a matter of logistics of the quantum computer, not of the actual computation.
Parent
Huh? (Score:4, Funny)
Parse error! Parse error!
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And fifteen, too. The roots of fifteen, three and five are all irrational, and since primes are integral and therefore rational, none of them can be prime.
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The cat was both shot, and not. It was half a tragedy. We all cried furiously, and didn't.
Me too! (Score:5, Funny)
I, too, have already calculated the prime roots of fifteen, with nearly identical results. Where's my DARPA funding?
Prime roots, eh? (Score:4, Funny)
Can't stop myself...oh the Humoranity! (Score:5, Funny)
A: A Qubicle
Q: How big is it?
A: About four Qubit meters.
Q: Qubit? Wasn't that an early arcade game with a little guy jumping around changing the quantum state of a bunch of Qubes?
I have OBVIOUSLY had too much Qaffeine.
It's Obviously... (Score:3, Funny)
That's no big deal (Score:5, Funny)
It's obvious that (Score:3, Funny)
DARPA (Score:3, Insightful)
I'm in trouble... (Score:5, Funny)
CRAP! 15 was my RSA public key!
What's a "prime root?" (Score:5, Informative)
For the sake of completeness, a primitive root of a prime p is an integer r such that the smallest positive value of k such that p divides r^k - 1 is k = p-1. For large primes, finding primitive roots is not a trivial task. For example, r = 2 is a primitive root of p = 5, since the positive integer powers of 2 are 2, 4, 8, 16, 32,
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Re:MATH (Score:4, Informative)
http://www.answers.com/maths&r=67 [answers.com]
Thanks fo the rant, though.
Parent
Yah. And we got there first (Score:2)
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The only place in the world I've encountered the word "math" is in North America.
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Doing the "mathematics" or doing the "mathematic" ?
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Yeah, like those who live in England, who are sometimes called the English?
In the US it is "Math", in the UK it "Maths". And non-native English speakers are taught British English, not American English, thus the affinity toward the way things are said in England.
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Correction: Some non-native speakers of English are taught British English, not all. Moreover, British English has not been the standard worldwide for many years, so outside of Commonwealth countries and Europe, people do not, as a rule, gravitate towards British English.
And no, all this has nothing to do with which dialectic is better. It's just sociolinguistics. American English is the premier language of commerce and political power. It's also the medium of a huge amount of popular culture and mark
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(Pun only moderately intended)
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"People who speak very good English"
Should be: "People who speak English very well".
"Almost as bad as "loose" instead of "lose", but non-native English speakers get a pass since they don't know any better."
Should be two sentences without the "but". You have several similar errors involving the word "But".
Additionally, please try to eliminate your use of run-on sentences.
Re:MATH (Score:4, Insightful)
Parent
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I think that the fact that we are here, almost 14 billion years after the universe began, is a good indication that it's not possible to "crash" the universe.
The original numbers plugged in the Drake Equation estimated 10 intelligent civilizations in our own galaxy. Since there are more than 100 billion galaxies, that me
Re:Law of conservation of time (Score:4, Interesting)
Phenomena like superposition and entanglement are not fully understood from the metaphysical point of view, and there is some hand-waving about that. But the mathematics agrees perfectly with experiment, and that's all we need to know to put the theory to use.
One possibility is that we ask the 'computer' of the universe to do too much computation and end up in an infinite loop, crashed universe, 'dark' part of a mandlebrot-like fractal, etc.
Another possibility is that the 'computer' of the universe will simply abort operations that take 'too long', the quality of our simulation will degrade, and our complex quantum math will result in randomish results.
How do we know building a quantum computer won't break the universe? Well, the things that go on in a quantum computer are the same things that go on in ordinary matter all the time. A speck of dust consists of some 10^20 particles that continually interact with each other according to the same quantum-mechanical laws that govern the interaction of qubits used in integer factorization. Why should the universe care what purpose we use those interactions for?
And in the end, a size/time-N quantum computation can be simulated with 2^N space and in 2^N time on a classical computer (I might be wrong about the exact form of those expressions). Would the universe collapse if we run a quantum algorithm on a PC?
And then there is the possibility held by quantum researchers that somehow the universe can magically perform any amount of complex computation with no cost at all.
This isn't true. Quantum algorithms have real costs that grow with the size of the problem, just like on ordinary computers. (Concretely speaking, we can simulate them on classical computers in deterministic time.)
Parent
Re:Quantum Computing Is Pure Unmitigated Bullshit (Score:5, Informative)
Well, fair enough, Einstein himself quoted 'God does not play dice' on this very issue, before coming to terms with it. You might have the best of intentions but unfortunately you're off track. Regardless of what anybodies opinion is the quantum uncertainty model accurately predicts all available data, and theories that coincide with empirical evidence are useful and usable no matter how small or great an understanding we have of the underlying processes.
Come up with a simpler theory that fits all the data and I'll gladly accept your claims of crackpottery, otherwise open your mind a little and realise that regardless of a deeper understanding, if the math fits, we can do it, ergo quantum computing is not just feasible, but is already happening as we speak in labs the world over, like the one in TFA.
Parent