Leo Kouwenhoven: ‘We should have been more critical’

Quantum Physicist Prof. Leo Kouwenhoven is putting on the hair shirt. After two years of silence about an integrity issue that largely revolves around him, he said in an Atlas podcast produced by NTR and to the Vrij Nederland magazine, that he should have been more cautious about the 2018 findings.

The case revolves around the Nature article entitled Quantized Majorana conductance published that year. In the article, the researchers, led by Kouwenhoven, wrote that they had detected Majorana particles. The findings seemed too good to be true. And they were. At the time, Kouwenhoven did not take enough note of this, he told Atlas. “Had I thought about it, I could have avoided all this.” And in a reconstruction in Vrij Nederland, he said “We were doing research into positive outliers and zoomed in on them. We should have been more critical in doing so. This is then a culpable confirmation bias.”

Obscure particles that have no mass or charge
Kouwenhoven has been in the spotlight for more than 10 years. In a 2012 Science publication, his team demonstrated the existence of Majorana particles. These are obscure particles that have no mass or charge, that may one day be used in highly powerful quantum computers. It was for this reason that Kouwenhoven entered into a partnership with Microsoft in 2016. But the definitive evidence that the particle had showed up in the lab was still missing. Until 2018 when the Volkskrant newspaper wrote ‘A peak in a measurement signal is the long awaited pièce de résistance’.

‘There were culpable errors, but no breaches of scientific integrity’

It did not take long for two former staff members of Nature to point out errors in the article. They suggested that the data had been used selectively. Nature withdrew the article and TU Delft’s Integrity Committee started an investigation into the research group’s methodology. Later, the Landelijk Orgaan Wetenschappelijke Integriteit (national agency for scientific integrity, LOWI) got involved and in February 2022, a second integrity investigation was started on the grounds that errors may have arisen in more publications. Further investigation led to further action, including Nature withdrawing a second article.

TU Delft’s Research Integrity Committee completed its work and presented it to the LOWI. Atlas’s Editorial Office was given access to the conclusions of the integrity investigation. It then concluded that ‘There were culpable errors, but they were not breaches of scientific integrity’.

The investigation will be made public soon
The investigation into the events leading to the Nature article of 2018 took two years. And the exact content is still guesswork. A TU Delft spokesperson announced that the integrity report will be made public shortly. A second investigation into a 2017 publication is still ongoing.

‘Frolov and Mourik put their reputations on the line and were then ignored’

The reputations of several scientists were damaged during the process. The situation was not only precarious for Kouwenhoven, but also for Sergey Frolov and Vincent Mourik, the whistle-blowers from the TU Delft research group. They complained about the way in which the integrity investigation was done. Nevertheless, the pair did not submit an official complaint to the LOWI. They were, however, promised that they would be involved in the TU Delft integrity investigation. The TU Delft Ombudsman alleges that TU Delft did not do this. “Frolov and Mourik put their reputations on the line and were then ignored,” he told Delta at the end of last year. “This gave rise to an unsafe situation for them. Make no mistake, you do not make yourself popular if you are a whistle-blower.”

For Kouwenhoven, the debacle ended on a bad note. Last month Microsoft terminated the partnership with the Professor. But he is not giving up. “The research went well last year,” he told Atlas. “We have measured new, home-made Majoranas and we will publish the information shortly.” And he says that he is considereing writing a book.