Test: Quantum Or Not, Controversial Computer No Faster Than Normal

sciencehabit writes The D-Wave computer, marketed as a groundbreaking quantum machine that runs circles around conventional computers, solves problems no faster than an ordinary rival, a new test shows. Some researchers call the test of the controversial device, described in Science, the fairest comparison yet. "...to test D-Wave’s machine, Matthias Troyer, a physicist at the Swiss Federal Institute of Technology, Zurich, and colleagues didn't just race it against an ordinary computer. Instead, they measured how the time needed to solve a problem increases with the problem's size. That's key because the whole idea behind quantum computing is that the time will grow much more slowly for a quantum computer than for an ordinary one. In particular, a full-fledged 'universal' quantum computer should be able to factor huge numbers ever faster than an ordinary computer as the size of the numbers grow." D-Wave argues that the computations used in the study were too easy to show what its novel chips can do.

Comments

The real question in my mind

[TFoo]

Is this a case where D-Wave was fraudulently trying to pass something off as quantum when they knew it wasn't, or did they really and truly not know. How could they not know?

Re:The real question in my mind

[Pinhedd]

No, it's simply a case of pitting a very immature technology against one that's very mature.

What problems are Quantum Annealers good for?

[billstewart]

That's been the big question with D-Wave all along. What does it really do, how does it really work, what's it good for, is it real?

Everybody knows what a universal quantum computer is good for - running Shor's algorithm to do factoring and totally wrecking public-key cryptography, plus whatever other problems people care about in the real world. But general-purpose quantum computers so far can't keep enough qbits entangled together to factor numbers bigger than 21 = 3x7, and if anybody's figured out how to do significantly bigger than that, they're keeping it Really Well Hidden (either because they're a government, or because a government will want them to do stuff, or because a government will want them killed.)

Meanwhile, D-Wave has 512 qbits that they claim they'll be able to do something with, and maybe it'll have a chance of being cool or useful. And maybe if you kick in enough megabucks to get a non-disclosure agreement, you'll be able to get some information beyond vague quantumy handwaving. They are the only game in town, after all.