In March 2018, Dutch physicist and Microsoft employee Leo Kouwenhoven published headline-grabbing new evidence that he had observed an elusive particle called a Majorana fermion.
Microsoft hoped to harness Majorana particles to build a quantum computer, which promises unprecedented power by tapping quirky physics. Rivals IBM and Google had already built impressive prototypes using more established technology. Kouwenhoven's discovery buoyed Microsoft's chance to catch up. The company's director of quantum computing business development, Julie Love, told the BBC that Microsoft would have a commercial quantum computer "within five years."
Three years later, Microsoft's 2018 physics fillip has fizzled. Late last month, Kouwenhoven and his 21 coauthors released a new paper including more data from their experiments. It concludes that they did not find the prized particle after all. An attached note from the authors said the original paper, in the prestigious journal Nature, would be retracted, citing "technical errors."
Two physicists in the field say extra data Kouwenhoven's group provided them after they questioned the 2018 results shows the team had originally excluded data points that undermined its news-making claims. "I don't know for sure what was in their heads," says Sergey Frolov, a professor at the University of Pittsburgh, "but they skipped some data that contradicts directly what was in the paper. From the fuller data, there's no doubt that there's no Majorana."
The 2018 paper claimed to show firmer evidence for Majorana particles than a 2012 study with more ambiguous results that nevertheless won fame for Kouwenhoven and his lab at Delft Technical University. That project was partly funded by Microsoft, and the company hired Kouwenhoven to work on Majoranas in 2016.
The 2018 paper reported seeing telltale signatures of the Majorana particles, termed "zero-bias peaks," in electric current passing through a tiny, supercold wire of semiconductor. One chart in the paper showed dots tracing a plateau at exactly the electrical conductance value that theory predicted.
Frolov says he saw multiple problems in the unpublished data, including data points that strayed from the line but were omitted from the published paper. If included, those data points suggested Majorana particles could not be present. Observations flagged by Frolov are visible in the charts in the new paper released last month, but the text does not explain why they were previously excluded. It acknowledges that trying to experimentally validate specific theoretical predictions "has the potential to lead to confirmation bias and effectively yield false-positive evidence."
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