Seasons
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OK, can someone explain to me how a quantum computer works better when it is turned off? Anagrams of your answer are optional.
Well, Lady Orchid got to the anagrams first, so I'll cover the science. Actually, the concept of "anagram" lies dead-centre at the heart of quantum computing. As a wise man (I forget who) once said: "all truth is to be found in anagrams - they never lie."
[GROSS OVERSIMPLIFICATION ALERT!]
Quick recap of how quantum computing works...
A quantum computer is very different from a "normal" computer because of the phenomenon of superposition - this is the effect where each quantum bit is simultaneously 1 and 0 (assuming a digital process for the sake of simplicity,) - we're back to Schroedinger's cat here, but not paradoxically so, since qubits necessarily fall well below the Planck divide @ 10^-35m. Qubits are usually coded using the properties of individual electrons - spin seems popular because it's a) binary, and b) easy to measure, but any properties could in principle be used.
So in a binary n-qubit computer, you would have n bits, and each encoded bit simultaneously represents 1 and 0. Thus there are 2^n states maintained in the processor before running the program, which equates precisely to 2^n "normal" non-quantum bits, and contains every possible combination (think "anagram" - I told you they rule the world ) of sequences of length n. That necessarily must include all possible answers.
Conventionally, only one value per bit can be practically obtained by measurement, because at the point of measurement the wave function collapses, the quantum uncertainty is resolved, and the specific answer to the question appears. You can program the "question" you're asking the quantum computer in a number of ways, but usually by firing photons at the qubits in a predetermind pattern, but by doing this, the computer effectively becomes the program, and once run is destroyed.
What the team appear to have done is get the answer out of the computer without having to trigger the wave function collapse, by letting the photon "pass-by" the qubit-coded particles in some manner (I'm not quite clear on "how", but then by the looks of it, not many people are!) without destroying the computer in runtime.
I have to slightly take issue with the New Scientist piece, which was a rather unfortunate example of over-condensed, third-hand reporting - it implies that the superposition state is somehow optional for quantum computing. It isn't. It is an integral part of the process, and the one that distinguishes quantum computing from "normal" computing. What is new (and very exciting!) is the practical implementation of the Zeno effect. There is a clearer explanation of this athttp://cosmicvariance.com/2006/02/28/paul-kwiat-on-quantum-computation/ but it's still going to make your head hurt to try to grasp it logically. If you find the prospect of abusing your brain till it comes dribbling out of your ears as entertaining as I do, you could also try http://www.physics.uiuc.edu/People/Faculty/profiles/Kwiat/Interaction-Free-Measurements.htm - from the guy who proposed the Zeno effect, and led the team that implemented it. That's straight from the mouth of Schroedinger's horse, as it were.
We live in exciting times!
Posts 3,197 - 3,208 of 6,170
Since we're on that kick, I once found this to be an amusing anagram of my first and last name:
P.S.: Hellish Pain.
P.S.: Hellish Pain.
The Personality Forge
Osteopathy erring elf
Telegraphy noise fort
Anthology priest reef
Flotation sphere grey
Foreigner hotel pasty
Telepathy senior frog
LOL I got a hang of it now
Osteopathy erring elf
Telegraphy noise fort
Anthology priest reef
Flotation sphere grey
Foreigner hotel pasty
Telepathy senior frog
"Telepathy, Senior Frog!"
For some reason, when I heard that, I imagined Holmes using that instead of his famous catchphrase.
For some reason, when I heard that, I imagined Holmes using that instead of his famous catchphrase.
OK, can someone explain to me how a quantum computer works better when it is turned off? Anagrams of your answer are optional.
http://www.newscientist.com/article.ns?id=mg18925405.700&feedId=online-news_rss2
0
http://www.newscientist.com/article.ns?id=mg18925405.700&feedId=online-news_rss2
0
how a quantum computer works better when it is turned off
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Non-compos-mentis heartbreaker thud turf tutu few wow iq
Non-compos-mentis tete-a-tete dwarf quirk hurt fur hub wow
Non-compos-mentis afterbirth quarter tutu we'd whew of uk
Well, Lady Orchid got to the anagrams first, so I'll cover the science. Actually, the concept of "anagram" lies dead-centre at the heart of quantum computing. As a wise man (I forget who) once said: "all truth is to be found in anagrams - they never lie."[GROSS OVERSIMPLIFICATION ALERT!]
Quick recap of how quantum computing works...
A quantum computer is very different from a "normal" computer because of the phenomenon of superposition - this is the effect where each quantum bit is simultaneously 1 and 0 (assuming a digital process for the sake of simplicity,) - we're back to Schroedinger's cat here, but not paradoxically so, since qubits necessarily fall well below the Planck divide @ 10^-35m. Qubits are usually coded using the properties of individual electrons - spin seems popular because it's a) binary, and b) easy to measure, but any properties could in principle be used.
So in a binary n-qubit computer, you would have n bits, and each encoded bit simultaneously represents 1 and 0. Thus there are 2^n states maintained in the processor before running the program, which equates precisely to 2^n "normal" non-quantum bits, and contains every possible combination (think "anagram" - I told you they rule the world
) of sequences of length n. That necessarily must include all possible answers.Conventionally, only one value per bit can be practically obtained by measurement, because at the point of measurement the wave function collapses, the quantum uncertainty is resolved, and the specific answer to the question appears. You can program the "question" you're asking the quantum computer in a number of ways, but usually by firing photons at the qubits in a predetermind pattern, but by doing this, the computer effectively becomes the program, and once run is destroyed.
What the team appear to have done is get the answer out of the computer without having to trigger the wave function collapse, by letting the photon "pass-by" the qubit-coded particles in some manner (I'm not quite clear on "how", but then by the looks of it, not many people are!) without destroying the computer in runtime.
I have to slightly take issue with the New Scientist piece, which was a rather unfortunate example of over-condensed, third-hand reporting - it implies that the superposition state is somehow optional for quantum computing. It isn't. It is an integral part of the process, and the one that distinguishes quantum computing from "normal" computing. What is new (and very exciting!) is the practical implementation of the Zeno effect. There is a clearer explanation of this at
We live in exciting times!
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