Features
Quantum Leap
Is it real?
On these terms, how successful has D-Wave been? No-one actually knows - even though the company carried out public demonstrations in February and November 2007. Orion, the 16-qubit system that D-Wave built using $44 million invested in the company, was shown over a live link from D-Wave's British Columbia lab to the Computer History Museum in Mountain View, California.
The Orion chip is built according to a well-established AQC design principle. Rings of superconducting niobium metal carry a current in either direction or a superposition of both. They are etched on to a chip using standard micron-level lithography, and linked together to form the AQC. It has to be cooled to a few milliKelvin (just short of absolute zero), and doing that doesn't require leading-edge science. Sixteen qubits should be enough to handle 64,000 simultaneous inputs.
D-Wave pronounced the demonstration a success, describing the system as a "systems-level proof of concept". Orion was slower than a home PC, but it searched a database of protein structures, worked out a wedding seating plan and solved Sudoku puzzles.
Since then, D-Wave has posted a couple of papers to the ArXiv list of open-access physics papers, and issued some white papers to people willing to sign a non-disclosure agreement. A video of the event is available on restricted access on D-Wave's site. So far, no-one else has been allowed to test the device - despite a promise
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"Since the demo we have been developing the support infrastructure for our projects and have used it to design, build and test seven generations of processor prototypes," says Rose. "Each of these generations has focused on a specific issue related to performance and/or scalability of commercial processors."
At the Supercomputing 2007 show in Reno, Nevada, on 12th November, D-Wave demonstrated its quantum computer for the second time. Dr Hartmut Neven, Google's expert on image-searching, provided help with a demo algorithm for image searching. However, D-Wave has yet to publish the results or discuss them in depth. The scientific community is sceptical, partly for this reason and partly because the demonstration shows nothing that can't be achieved with conventional computers. Before the demonstration in Reno, Rose told us that "while the computing power is still not enough to compete with conventional silicon, it will run an application co-developed by an industrial partner".
According to Rose, D-Wave is still on target to make a 1,000-qubit computer that can be integrated into conventional database systems in the third quarter of 2008.
What's in the box?
Professor Vazirani remains unconvinced, however. "D-Wave's demo consisted of a computer in a box that could solve simple problems. We have no way of knowing whether the computer in the box was an ordinary classical computer or a quantum computer."
Scott Aaronson doesn't believe that Orion will be very useful. In a talk given at Google's offices, he said: "They apparently built a device with 16 very noisy superconducting qubits." Qubits that are noisy - that let information into the environment - behave like classical bits, he points out. "It's consistent with the evidence that what D-Wave actually built would best be described as a 16-bit classical computer. I don't mean 16 bits in terms of the architecture; I mean 16 actual bits. There's some prior art for that."
