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Solid State Quantum Computer Finds 15=3x5 — 48% of the Time
mikejuk writes "The Shor quantum factoring algorithm has been run for the first time on a solid state device and it successfully factored a composite number. A team from UCSB has managed to build and operate a quantum circuit composed of four superconducting phase qubits. The design creates entangled bits faster than before and the team verified that entanglement was happening using quantum tomography. The final part of the experiment implemented the Shor factoring algorithm using 15 as the value to be factored. In 150,000 runs of the calculation, the chip gave the correct result 48% of the time. As Shor's algorithm is only supposed to give the correct answer 50% of the time, this is a good result but not of practical use."
To be fair, it could have been either until we looked.
(And you could have posted either here or at the correct story.)
Consider problems which take a lot longer to compute than to verify. It may be much faster to compute the answer with a quantum computer, then check it with a regular computer, than to simply compute it with a regular computer.
How is it useful to have the correct answer 50% of the time?
Cat life-support devices.
Historically, they're a bit more tolerant about that math thing.
It seems that quantum computing has consistently been viewed as harder than it really is, judging by the ever-decreasing timescales between breakthroughs. Judging from the history of cryptography, and the military value of being able to break RSA, it's not unreasonable to expect that the NSA may have been trying to build such a chip for some time and could potentially have succeeded.
Some months ago James Bamford, who is the premier chronicler of the NSA and has a history of being given accurate leaks, claimed the NSA had made a "huge breakthrough" in its ability to break codes - and that the datacenter they're currently building is a part of the solution. The NSA denied everything of course. But if academics are now able to build a working implementation of Shors algorithm for small numbers, that strongly implies that a focussed team with practically infinite budgets could have already succeeded in building one that can handle crypto-sized numbers.
If you can factor really large prime numbers,
I can factor really large prime numbers in my head.
That may be so, but computing the prime factorization of 15 is not in that class.
I don't think you should even get to call something a middle-school dropout can figure in his head faster than he can say "Fries with that?" computation. So-called quantum computers still barely qualify as expensive but useless toys.
Post again when a quantum computer can solve a real mathematical puzzle at a speed comparable to what a traditional computer can do. That would be news.
Scientists have been touting the supposedly vast potential of quantum computing for decades now. D-E-C-A-D-E-S. But thanks to fundamental limitations of the nature of what they are, it's really hard to get them to barely work at all. It appears we could forever be stuck at the point where the qubits can be minimally processed but quantum decoherence can't be held off long enough to get a useful result. Meanwhile traditional methods of computing continue to forge ahead, although the rate of increase is slowing. Just keep in mind: quantum computing is 2500 years behind traditional computing methods in general, 175 years behind automated mechanical methods and more than 70 years behind electronic computers.
Electronic computing methods overtook all other methods extremely quickly, but they faced only technical challenges not challenges posed by the fundamental nature of what they were trying to do. You can regard them in some ways as fancy abacuses: they literally count chunks of charge the way an abacus uses the position of beads to represent numbers (or in principle anything else). With qubits, you are attempting to get definite results by exploiting the indefinite character of things like the spin states of electrons. That's not just hard. It may be intractably hard. But if somebody can get it to work it might be very valuable to the NSA and anybody else interested in cracking the security of computing systems.
There should be a "-1 Bitching That This Doesn't Meet My Personal Criteria For News" mod. Every. Damn. Article. Somebody has to come write an essay on how completely not interesting or impressive this is to them.
Yes, factoring 15 isn't particularly impressive. Thank you, Captain Fucking Obvious.
Now if you'd bothered to RTFA, you'd have noted it already directly discusses this:
So they can instantly factor numbers (well, with ~50% success), with an approach that *seems scalable*. That's news to me.
Maybe in a few months, there will be another story about how they failed to scale this approach up. That will be an additional piece of news. Failure can be news.
Some of us are interested in the journey, not just the destination.
"Mind, as manifested by the capacity to make choices, is to some extent present in every electron." -Freeman Dyson