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.