A new academic study has raised doubts about the performance of a commercial quantum computer in certain circumstances.
In some tests devised by a team of researchers, the commercial quantum computer has performed no faster than a standard desktop machine.
The team set random maths problems for the D-Wave Two machine and a regular computer with an optimised algorithm.
Google and Nasa share a D-Wave unit at a space agency facility in California.
The comparison found no evidence D-Wave's $15m (£9.1m) computer was exploiting quantum mechanics to calculate faster than a regular machine.
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