D-Wave’s Year of Computing Dangerously: Is it, or isn't it a quantum computer?

When in 1935 physicist Erwin Schrödinger proposed his thought experiment involving a cat that could be both dead and alive, he could have been talking about D-Wave Systems. The Canadian start-up is the maker of what it claims is the world’s first commercial-scale quantum computer. But exactly what its computer does and how well it does it remain as frustratingly unknown as the health of Schrödinger’s poor puss. D-Wave has succeeded in attracting big-name customers such as Google and Lockheed Martin Corp. But many scientists still doubt the long-term viability of D-Wave’s technology, which has defied scientific understanding of quantum computing from the start.