Canadian D-Wave quantum computer stands up to scrutiny

Ever since D-Wave Systems went to market with what it described as the world’s first commercially available quantum computer in 2011, the Burnaby, B.C.-based company has come under constant pressure to prove its claims. Specifically in question is whether the D-Wave One processor uses quantum effects to solve complex optimization problems, and that it can do so much faster than classical digital processors.

In an effort to answer those questions, an international team of scientists recently announced that a battery of tests run on a first-generation D-Wave One processor housed at USC Viterbi School of Engineering’s USC-Lockheed Martin Quantum Computing Center (QCC) show the quantum processor conformed to the “quantum Monte Carlo” model. The tests, which included one test of the chip’s 108 functional quantum bits or qubits, also disagreed with proposed classical computing models that could have described the processor in the absence of quantum effects.

Unlike digital bits, which encode data as either a 1 or a 0, quantum processors, like D-Wave’s, crunch qubits, which can represent data as both numbers at the same time. This property, along with the ability of quantum states to cancel or reinforce each other and “tunnel” through energy barriers, is what may one day allow quantum processors perform optimization calculations much faster than traditional processors. It’s hoped that quantum processors will be able to tackle big data problems like stock portfolio optimization, image recognition and classification and rooting out bugs in complex software.

While the research results – published in February by scientific journal Nature Physics – look promising for D-Wave, the researchers say it isn’t definitive proof but adds to the mounting evidence that D-Wave’s processors do use quantum effects.

“The challenge is that the tests we can perform on the USC-based D-Wave processor can’t directly ‘prove’ that the D-Wave processor is quantum – we can only disprove candidate classical models one at a time,” said QCC Director Prof. Daniel Lidar. “But, so far, we find that the D-Wave processor is always consistent with our quantum models. Our tests continually get more rigorous and complex.”

The research was funded by the Swiss National Science Foundation, the Army Research Office, the Lockheed Martin Corporation, DARPA, and the National Science Foundation.
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