Why Nobody Can Tell Whether the World’s Biggest Quantum Computer is a Quantum Computer


Leo Mirani and Gideon Lichfield in Quartz (via Jennifer Ouellette, D-Wave Systems photo):

For the past several years, a Canadian company called D-Wave Systems has been selling what it says is the largest quantum computer ever built. D-Wave’s clients include Lockheed Martin, NASA, the US National Security Agency, and Google, each of which paid somewhere between $10 million and $15 million for the thing. As a result, D-Wave has won itself millions in funding and vast amounts of press coverage—including, two months ago, the cover of Time (paywall).

These machines are of little use to consumers. They are delicate, easily disturbed, require cooling to just above absolute zero, and are ruinously expensive. But the implications are enormous for heavy number-crunching. In theory, banks could use quantum computers to calculate risk faster than their competitors, giving them an edge in the markets. Tech companies could use them to figure out if their code is bug-free. Spies could use them to crack cryptographic codes, which requires crunching through massive calculations. A fully-fledged version of such a machine could theoretically tear through calculations that the most powerful mainframes would take eons to complete.

The only problem is that scientists have been arguing for years about whether D-Wave’s device is really a quantum computer or not. (D-Wave canceled a scheduled interview and did not reschedule.) And while at some level this doesn’t matter—as far as we know, D-Wave’s clients haven’t asked for their money back—it’s an issue of importance to scientists, to hopeful manufacturers of similar machines, and to anyone curious about the ultimate limits of humankind’s ability to build artificial brains.

More here.