TECH
01/07/2013 11:38 BST | Updated 31/08/2013 10:12 BST

Google's 'D-Wave' Might Be A Truly Quantum Computer After All, Research Indicates

When the D-Wave computer was first unveiled, it was described as the "world's first commercial quantum computer".

And while it's undoubtedly a fast machine - and was snapped up by Google and Lockheed Martin, among others - some suspected that it might not be quite what it claimed.

The point of interest depends on whether the D-Wave is actually a quantum machine - an idea first proposed in the mid-1980s by British physicist David Deutsch - in which information can be held in two states at the same time, or just a normal computer running on new principles, but the same set of physical laws.

Unlike in a normal computer - where information is either ones or zeroes - a quantum computer would use the almost totally insane physics of the very small to hold information as "qubits", where a bit could hold both data points at once - known as a "superposition".

The result of this is that two pieces of superposition data could have four values (00, 01, 10, 11), and by extrapolating this out computers can be exponentially more powerful.

The problem, as Wired neatly explains, is that once you read information from a qubit it decoheres, and resolves itself into a bit with only one value of information. Until now computer makers haven't been able to practically overcome this inherent problem in quantum physics well enough to have a workable machine beyond a few qubits.

Which is where the D-Wave comes in. The creators of the D-Wave say their machine is able to use up to 128 qubits - a vast improvement, and if true a remarkable achievement. Their machine contains super-cooled circuits where current can flow in both directions simultaneously - they say - and so can use "quantum annealing" to run calculations.

Quantum annealing is a way of solving optimisation problems using quantum principles - which is, in theory, much faster than traditional methods.

And while the machine is still controversial, some scientists who have looked into the device say they're starting to come around.

A team of USC physicists who studied the USC-Lockheed Martin D-Wave say they now believe quantum mechanics "plays a functional role" in the way it works.

"Using a specific test problem involving eight qubits we have verified that the D-Wave processor performs optimisation calculations (that is, finds lowest energy solutions) using a procedure that is consistent with quantum annealing and is inconsistent with the predictions of classical annealing," said Daniel Lidar, scientific director of the Quantum Computing Center.

"Our work seems to show that, from a purely physical point of view, quantum effects play a functional role in information processing in the D-Wave processor," added Sergio Boixo, first author of the research paper.

There will now be further testing of the machine, including the new 'Vesuvius' chip which contains up to 512 qubits.