A year after retracting a Nature paper claiming to find evidence for the elusive Majorana particle that many hope would have paved the way for a quantum computer, a group of researchers have retracted a second paper on the subject from the same journal.
In the August 2017 paper “Epitaxy of advanced nanowire quantum devices,” Erik Bakkers of QuTech and Kavli Institute of NanoScience, Delft University of Technology, in The Netherlands, and colleagues claim that the work is a “substantial materials advancement that paves the road for the first Majorana braiding experiments.” The paper has been cited 189 times, earning it a “highly cited paper” designation from Clarivate Analytics’ Web of Science.
But the Majorana story has been unraveling after other physicists began raising questions. In March 2021, the group retracted a Nature paper. That was followed by an expression of concern for related work in Science in July, and another expression of concern in Science in December.
Here’s the notice for the newly retracted Nature paper:
The authors of the paper “Epitaxy of advanced nanowire quantum devices”1 wish to retract this work. When preparing the underlying data for public release2, it was discovered that some data had been inappropriately deleted or cropped when preparing the final published figures, and we promptly alerted the editors of Nature. We found unjustified data removal and cropping in Figures 4a and c, and Extended Data Figures 7 and 8, which affect the agreement between the theoretical curves and the experimental data and the claims of ballistic transport. We are accordingly retracting the paper. The authors stand by all the other data, and their contribution to advanced nanowire quantum devices. All authors have agreed to this retraction.
Vincent Mourik, who along with Sergey Frolov has raised red flags about the body of work, tells Retraction Watch:
This paper suffers from similar problems as the retracted Nature paper from 2018, and forms part of a pattern of multiple unreliable papers from the research team at the QuTech institute. The electronic transport data is severely misrepresented through a variety of undisclosed data manipulation and selection issues, and claims about confirming a high quality material interface based on these data are unreliable. The overarching claim of this paper can be paraphrased as a demonstration of the perfect material to conclusively demonstrate Majoranas. Since this claim is no longer supported, we have long recommended this paper to be retracted and we are relieved this has finally happened.
He also said that he and Frolov were rebuffed when they tried to raise concerns about the work:
We notified the integrity committee of Delft University of Technology as early as 1 June 2020 of the suspected problems with this and multiple other articles, in the context of the investigation into the retracted Nature 2018 paper which was then just commencing. However, Jeroen van den Hoven, the chairman of that committee, refused to investigate any additional paper, withheld our evidence from that investigation, and refused to facilitate data sharing, greatly delaying our ability to independently investigate this paper. Failure to share data was supported by the highest leader at Delft University of Technology, Rector Magnificus Tim van der Hagen, with the effect of downplaying the scope and severity of the unreliable research articles. Given the huge investments from national and European public funds into quantum research at Delft University of Technology, we believe the senior leadership at Delft University of Technology should be held accountable for the harm they caused by not providing enough clarity in this matter, through hindering and delaying any broad and independent integrity investigation into this matter.
van den Hoven did not respond to a request for comment on these allegations.
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