The authors of the 2018 article Quantized Majorana conductance have retracted this article. The authors were alerted to problems by two scientists in the same research area and then went on to re-examine their earlier measurements. In doing so, they found that the main conclusion had not been adequately substantiated.

As part of its ongoing investigation into this matter, TU Delft’s Scientific Integrity Committee has asked independent international experts to provide an objective opinion on the publication. In the public part of the expert report, the experts state that the way the results were presented in the manuscript shows that the authors selected data that supported the phenomenon they were looking for, while omitting data that could have raised questions about the conclusions presented. The international experts found no evidence that this may have been intentional. The experts consider the most plausible explanation to be that the authors were caught up in the enthusiasm of the moment and thus did not pay enough attention to data that did not suit their purpose.

“It is a good thing that independent experts have looked at this as part of the integrity investigation,” says Tim van der Hagen, Rector Magnificus of TU Delft. “Science always involves looking critically at results, questioning and challenging them.” Only after completion of the full procedure as set out in the Complaints Regulation for Scientific Integrity, can TU Delft’s Executive Board provide more information about possible changes in working methods within TU Delft.

Quantum research
“The retraction of the article is obviously a setback in Majorana research towards the development of a quantum computer,” says Lieven Vandersypen, scientific director of QuTech, TU Delft and TNO’s research centre for quantum technology. “Reflection on the methods used, must now run its course within the scientific community. Within QuTech we have already started that discussion. At the same time, we are continuing to work hard on our various lines of research towards the realization of a quantum computer and a quantum Internet.”

The Majorana particle forms the basis of one of the four lines of research along which QuTech is pursuing the development of a quantum computer. At QuTech, other building blocks for the quantum computer, based on superconductors, semiconductors and diamond, are also being researched. These types of quantum bits (also known as qubits) are part of the catalyst programme of the National Agenda for Quantum Technology.

Majorana research is also continuing. Scientists must now address how Majorana particles can be unequivocally demonstrated. Qubits based on Majorana particles might in principle be more robust than other types of qubits.

Collaboration with Microsoft
QuTech and Microsoft continue their collaboration in quantum computing research. It remains essential to partner leading-edge science with advanced engineering from companies such as Microsoft.

Open data
Since October 2018, QuTech has been following the open data policy of TU Delft’s Quantum Nanoscience department. It is committed to making the raw data behind each publication publicly available, along with the data analysis at the time of publication. Alongside the retraction of the Nature article, the authors have made this information publicly available, together with the unpublished data that was part of their research.