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Significant Advance in Quantum Computing
wcitech writes "Apparently scientists have been able to create circuitry that mimics the behavior of atom pairs by using superconductors." From the article: "The work, reported in the Feb. 25 issue of the journal Science, demonstrates that it is possible to measure the quantum properties of two interconnected artificial atoms at virtually the same time. Until now, superconducting qubits--quantum counterparts of the 1s and 0s used in today's computers--have been measured one at a time to avoid unwanted effects on neighboring qubits." The second Quantum computing revelation this month, in fact.
Before I go worrying about quantum computers, I need to get my own working. But in a quantum world, I guess they are working AND messed up at the same time.
'Every story, if continued long enough, ends in death.' --Ernest Hemingway
No fair! You changed the outcome by measuring it!
-- Thou hast strayed far from the path of the Avatar.
"So, computers. I hear they basically break down to a bunch of ones and zeroes. I don't know how that means I can see naked women on my screen, but God bless you people"
vodka, straight up, thank you!
Wikipedia has a good comparison of the differences between a traditional register and a quantum register (qubits).
Illegal? Samir, This is America.
"Two entangled qubits, meanwhile, can simultaneously evaluate four inputs. Put another way, a traditional memory register with eight bits can store only one of a possible 28, or 256, digital "words," but a quantum register with eight qubits can represent and compute with all 256 words at once."
So, If you get all possible answers simultaneously, how do you tell which one is the right answer to the problem you're working on?
Quantum computing: a view from the enemy camp
Quantum computing relies on processing information within a quantum system with many continuous degrees of freedom. The practical implementation of this idea requires complete control over all of the 2^n independent amplitudes of a many-particle wavefunction, where n>1000. The principles of quantum computing are discussed from the practical point of view with the conclusion that no working device will be built in the forseeable fu
The previous poster was right. The q-registers are QM wavefunctions where the eigenstates represent possible solutions to the problem being computed. You are allowed to manipulate the wave function via quantum (hamiltonian IIRC) operators to your heart's content, but you can only measure one of the eigen states at a time. the tricky part is manipulating a q-register wave function such that the right answers are represented by eigenstates that are more probable than the ones that are wrong. It solves probablistic algorithms, and you don't a QC to do that. What a QC gives you is a way of operating on all possible states at once, whereas a regular turing machine type of computer can only act on one state at a time. This ability allows for a greater range of problems to be tackled in polynomial time by QM probablistic algorithms, such as, famously, factoring a number into its primes.
Quantum computers can change the rate at which problems are solved, but not whether or not a solution is technically achievable through computation.
Goldbachs' conjecture and the Riemann hypothesis might be provable through an accelerated brute forcing of all possible proofs if, for example, P=NP and algorithmic degrees and coefficients are reasonable, but this is only because such a brute force may be doable already with a sufficiently ginormous length of time (assuming that they are in fact provable to begin with, which some true propositions are not (unless our math is internally inconsistent)).
The halting problem cannot be solved for arbitrary Turing machines. Period. No algorithm, as we think of them, using quantum computers or not, will get around the fact that such a solution would create a logical inconsistency (a program could determine whether or not it itself would halt, and then do the opposite, but then it would have been wrong, which it can't be by assumption, and so reality bursts into flames). The only possible catch is that a technique that cannot be encoded in a Turing machine would not cause this particular logical inconsistency to arise. Basically this leaves an opportunity for solution through revelation. Or not, depending on your philosophical persuasion towards flaimbait and the rest of existence.
Again, though, quantum computers do not allow one to execute algorithms that are beyond simulation (albeit more slowly) on classical computers. What ifs are fun, but this one, at least in part, is worse than baseless.
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