A new research paper says Microsoft exaggerated its quantitative claims a year ago

A Criticism published in nature Wednesday puts the core technology behind Microsoft’s “cutting-edge” quantum computing chip, Majorana 1, into question. Microsoft unveiled the chip in February 2025, and said it featured an entirely new technology known as topological qubit. Topological qubits will serve as the “building blocks” for a future quantum computer, they said. Microsoft Announcing the next generation Majorana 2 chip In Build earlier this month.

But in a peer-reviewed article, Henry Legg, a physicist at the University of St Andrews, reanalyzed Microsoft’s data on their devices and said the company’s researchers had not conclusively demonstrated the existence of a functional topological qubit in the first place.

Proponents of quantum computing expect that the technology’s computational capabilities will advance the discovery of new medicine, cryptography, and machine learning. Companies Like Google And IBM Machines more advanced than Majorana 1 or 2 have already been demonstrated, although at the moment, no one has conclusively been able to get any quantum computer to perform anything useful. But Microsoft claimed that Majorana 1, and then Majorana 2, paved the way toward a practical quantum computer.

Microsoft’s design, unique among quantum computing companies, involves a tiny wire, thinner than a human hair, made of the semiconductor indium arsenide bonded to a superconductor. Theory predicts that the electrons in this wire behave in a collective pattern known as a Majorana particle, after which the chip is named. Microsoft wants to encode information in the properties of the Majorana particle. (A topological qubit is to a Majorana particle what a transistor is to silicon.)

Proponents of the Majorana particle believe it is a promising qubit material because theory predicts that when formed into topological qubits, the Majorana particle should compute with fewer errors than competing materials, such as IBM’s superconducting circuits. This suggests that eventually, fewer topological qubits are needed to scale up to a useful quantum computer.

That is, if Microsoft actually made a Majorana particle. “They have not convincingly demonstrated that they have Majorana,” Legg said. Edge. “You can’t make a qubit if you don’t have Majorana.”

In Legg’s critique, he wrote that what Microsoft claims is a signature of the Majorana particle could actually be from the formation of quantum dots, which are structures containing an electron, in the device. Quantum dots will not be useful in building a quantum computer. He also writes that Microsoft carefully selected their data.

The Microsoft team posted a rebuttal in nature Disputing Legg’s interpretation of their data. The Microsoft team wrote that Legg’s criticism “does not pose a significant scientific challenge to our findings.” Chetan Nayak, a physicist who leads Microsoft’s quantum team, said Legge did not “propose an alternative model that fits all of our data.” Edge.

Legg first published his critique on the online physics repository arXiv on February 26, 2025, within a week of Microsoft announcing Majorana 1. It took a year to nature To conduct peer review and publish his article.

Meanwhile, on June 2, Microsoft announced a new chip, Majorana 2, featuring what it claimed was its next generation topological qubits. The company says it can build a “scalable quantum computer” by 2029. “We stand behind our results 100%,” Nayak said. Edge. “We stand by our roadmap. We stand behind our long-standing commitment to scientific rigor and dialogue.”

Legg says the company’s description of Majorana 2, which Microsoft wrote in a manuscript that was not peer-reviewed, suffers from the same problem. The problems he pointed out a year ago. “There is nothing in this (manuscript) that resolves the fundamental issues that many scholars have with this company’s previous claims,” Legg said. Edge.