
Nearly a year after marking an article about the elusive “Majorana” particle with an expression of concern, and nearly three years after publishing a criticism of its reproducibility, Science withdrew the article due to “serious irregularities and discrepancies” in the data.
A few articles about Majorana particles, which would be useful in quantum computing if scientists could actually produce and detect them, have been retracted, flagged with expressions of concern, or have proven difficult to reproduce.
The latest paper to be retracted, “Chiral Majorana fermion modes in a quantum anomalous Hall insulator–superconductor structure,” has been cited more than 400 times since its publication in 2017, according to Clarivate’s Web of Science. About 10 percent of those quotes have come from ScienceThe editors published their expression of concern last December.
The notice of withdrawal specifies:
On July 21, 2017, Science published the report “Chiral Majorana fermion modes in a quantum anomalous Hall insulator–superconductor structure” by QL He et al. (1). Readers who failed to reproduce the results asked the authors for raw data files, which they provided. Subsequently, the source of the raw data was questioned; furthermore, an analysis of the raw and published data revealed serious irregularities and discrepancies. These problems caused the publishers of Science lose all confidence in the conclusions of the article, and so we proceed with an editorial retraction. Authors AL Stern, J. Wang and B. Lian agree with this decision. Authors QL He, L. Pan, X. Che, G. Yin, ES Choi, K. Murata, X. Kou, Z. Chen, T. Nie, Q. Shao, Y. Fan, K. Liu, J. Xia , and KL Wang disagree with this decision. Authors EC Burks and Q. Zhou did not respond. Author SC Zhang has passed away.
This retraction replaces the editorial expression of concern published on December 16, 2021 (2).
We contacted Holden Thorp, editor of Sciencewith a few questions to flesh out the retraction notice, and received this response from a spokesperson:
Science The editorial made its decision after consulting a number of experts, which they did under a confidentiality agreement. After careful and exhaustive deliberation, the editors have concluded that there is no scientifically plausible explanation for the irregularities in the files the authors originally provided when asked for raw data.
None of the paper’s corresponding authors — including last author Kang L. Wang of UCLA and first author Qing Lin He, a former postdoctoral fellow at UCLA and now an assistant professor at Peking University in China — or one of the authors who agreed with the retraction decision responded to our requests for comment.
Questions about the retracted article became public in January 2020, when Science published an article by a team of scientists from Pennsylvania State University and the University of Wurzburg who found its claims unrepeatable.
We asked a few of the authors if they could fill in the gaps in the retraction notice. Laurens Molenkamp, one of the scientists from the University of Würzburg, told us:
Yes, you guessed it right, we were involved in the withdrawal process. [Three authors from Penn State, Cui-zu Chang, Nitin Samarth, and Moses Chan, told us they were not involved in the retraction.]
You must realize that the experiment in the article, which was suggested by theorists, seemed very unlikely to succeed to an experimenter in the field, like us. Reading the article itself directly led us to ask serious scientific questions and we contacted the authors about the data. After a while, the authors provided us with a data file, but the analysis of this data file made us even more worried about the numbers in the publication. As some authors did not want to imply [us] in subsequent discussions, we alerted Science to inconsistencies between the data file and the actual numbers, as well as between the data the authors chose to present and the remaining data available in the file.
Eventually, this led Science to suggest that we write the paper in which we show that the original results cannot be reproduced.
What happened next were the retractions of other Majorana papers (rather different experiments by other groups on localized Majorana states, not the “flying” ones in the retracted Science paper). Since the lack of scientific rigor in these papers was actually less severe than what we found in the data we had, we went back to the science. This then led to the expression of concern and now to the retraction.
Two experts in the field who have found problems in other Majorana articles, Sergey Frolov from the University of Pittsburgh and Vincent Mourik from Forschungszentrum Jülich in Germany, described to us in an email the problem with the retracted article. more directly:
This data was invented. The people who found this did an amazing job. They found so many glitches and artifacts, it’s absolutely brilliant.
For the papers with which Frolov and Mourik found problems, they said:
the key issue was extreme data selection. Whether the data is made up, as in this article by Chiral Majorana, or whether the conclusions are made up but illustrated by handpicked data makes no difference. Triage to convince the editor/referee/reader of a false conclusion is just as bad and can be harder to prove. We hope the editors of Science understand this.
Frolov and Mourik also said they “applauded the editors of Science” for retracting the article:
Publishers are afraid to take this step, but they really shouldn’t. The law is on their side, especially in situations like this, where it is painfully obvious that the paper is not valid.
At Science, they seem to be reinventing their approach to situations where they can’t get the university to do a proper investigation. See the editor’s recent editorial, which is a step in the right direction, and all journals should pay attention to it. [RW: We have some questions about how the model in the editorial would work]. Science has also twice published negative replication studies of Majorana’s experiments, including one experiment where a group of researchers failed to replicate the findings of this now retracted paper. It deserves separate praise that science does this. In contrast, Nature journals offer the publication of reproductive studies in lower-impact journals within their broad family. This discourages reproductive work and reduces its impact.
Majorana particle research can be confusing, they said, due to its complexity:
Majorana physics is a complex and at the same time fascinating subject of modern science, which requires cross-cutting expertise. It is therefore particularly sensitive to unreliable claims, as few experts can fully assess the results. Unfortunately, we see a lot of attrition in terms of unfulfilled claims, and it’s not just bad science, but also unreliable research. Majorana’s subject isn’t the only one suffering from this dynamic, and some areas are maturing beyond that, so we’re hoping that’s what’s happening here.
Molenkamp shared Frolov and Mourik’s concerns about the pitch:
And yes, I am concerned about the impact these retractions may have on my field of research. I’ve been working on topological physics for a long time now, basically from the beginning, and it’s not nice to see the reputation of the field damaged by the kind of serious issues displayed by the now retracted articles.
That being said, I believe that topological superconductivity and Majorana states will be exploited, but not with the approaches followed by the now retracted papers.
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