Google’s quantum computer just flunked its first big test

[nedo]

When the D-Wave 2 was first released last year, it was accompanied by a tidal wave of hype. The machine was a self-proclaimed quantum computer, commercially available to anyone with $15 million to spend, and attracting the attention of everyone from NASA to the NSA. One of the computer’s buyers was Google, which launched a new lab to test the device's powers more rigorously than they’d ever been tested before. This October, the lab announced a major discovery, providing stronger evidence for quantum effects within the D-Wave 2 than anyone had previously found. As D-Wave had claimed, its device really was quantum-powered — and Google’s big research bet seemed to be paying off.

But today, the D-Wave 2 is facing its first big stumble. A study in Science found that the quantum device is no faster than conventional computing, calling into question the entire premise of Google's lab and D-Wave's machines. Led by scientists at ETH Zurich, the research team matched up the quantum machine against conventional computers on a set of problems intended to suit the quantum machine's strengths. (The project also got a crucial assist from Microsoft Research, which tested out the classical simulations on its high-powered computer clusters.) Once the results were in, the team found no clear advantage on either side. The D-Wave machine might be quantum-powered, but it didn't run any faster because of it.

THE TEAM FOUND NO CLEAR ADVANTAGE TO THE QUANTUM COMPUTER

The research was hoping to find what’s called "quantum speedup," the property that lets a quantum computer perform tasks faster than a conventional one, with more and more advantage as the problems grow more complex. The speedup is quantum computing's big advantage: with it, a quantum computer could tackle mind-bogglingly complex problems that would take a conventional computer years or even centuries. Without it, you're left with a lot of expensive hardware and no clear advantage. "It's hard to show that the speedup isn't happening," says Matthias Troyer, who co-authored the Science paper. "But if you don't find the speedup, you can't show that the machine is better than a classical device."

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