Quantum computer not as fast as maker D-Wave Systems claims, study shows

Lockheed Martin bought the first one in 2011. Two years later, Google, Nasa and the non-profit Universities Space Research Association followed, pitching in together to launch a lab with their new US$10 million-plus toy.

The machines in question are built by D-Wave Systems, the world's only commercial quantum computer company, and are clearly a hot-ticket item.

But the company's bold claim that the computer is thousands of times faster than a conventional PC have ruffled the feathers of academic quantum computing experts, who have been highly sceptical.

Now, new results may give weight to those doubts. An independent research group has found that its second-generation machine, D-Wave Two, shows no evidence of quantum speed-up, a measure of how well a quantum computer is outperforming a conventional PC.

The study was published online on Thursday in the journal Science. It pitted Lockheed Martin's D-Wave system against a conventional PC, posing each a set of problems that gradually increased in difficulty.

"When we just looked at the times - the boring question, basically -for some special problems, D-Wave was 10 times faster," said study author and physicist Professor Matthias Troyer of ETH Zurich. "For other problems, D-Wave was 100 times slower."