D-Wave Systems, whose controversial prototype quantum computer has been shown at supercomputer shows in 2007, has gathered up $17 million in venture capital to fund the development of a commercial system - despite the doubts of quantum scientists.

Quantum computing, if it can be developed, could speed up processor power by a vast factor, essentially by running multiple processes in parallel quantum states.

D-Wave will use the money for product and business development, said the company, which showed prototypes in February 2007, and at the SC07 supercomputing show in November, using an algorithm developed with Google.

"We are still on schedule to deliver a 500 qubit [quantum bit] quantum processor and machine in Q3/08, and a 1000 qubit processor by the end of the year," said Chris Hipp, director of marketing at D-Wave. The company plans to build co-processors for conventional computers, which it has promised to put online in early 2009, and then deliver to server rooms , and accelerate pattern matching and optimisation problems in biochemistry and finance.

However, D-Wave is the only commercial quantum computer company, and university researchers have mostly been sceptical about its claims. November's demonstration was of a 28 qubit system, and critics said D-Wave could not actually prove it was working in a truly quantum fashion. "My conclusion is that I suspect they are misleading themselves," said professor Andrew Steane of the centre for quantum computation at the University of Oxford, after the November demo.

This has led to speculation that D-Wave's plan may be more about applying quantum computing patents, of which it owns 42, some of them acquired in exchange for funding academic projects, according to the nextquant blog.

Quantum computing has been difficult to build and demonstrate because quantum computers only exist in a quantum state when there is no interaction with their surroundings. D-Wave uses "adiabatic" quantum computing in which interaction is allowed (more explanation here).

"Our vision is to make quantum-computing power available globally and to accomplish this requires a network of international partners,” said D-Wave chief executive Herb Martin. This is D-Wave's third round of funding, and brings the total investment to around $47 million.