Microsoft’s controversial claim that its Majorana chip program will make possible a scalable quantum computer by 2029 has been thrown into new doubt by a scientific paper that questions whether the company has correctly interpreted its own experimental evidence.

According to a peer-reviewed paper by Dr. Henry Legg from the University of St Andrews, published this week in Nature, Microsoft’s Topological Gap Protocol (TGP) framework, designed to infer the existence of quantum states in theorized Majorana particles, is flawed.

“Last year Microsoft claimed they had built the equivalent of a precision Swiss watch. However, when I opened the case to examine the mechanism, I found what looked like a chaotic jumble of mismatched parts,” said Legg.

He believed the results gathered from Microsoft’s TGP software data analysis could also be explained by other effects, as well as being skewed by the data chosen for analysis. Because of this, he believed the company’s researchers had jumped to the wrong conclusions.

“Something was making noise, but it didn’t look like the breakthrough Microsoft had claimed. Despite the headlines, the vast majority of scientists in the field were skeptical of Microsoft’s claim from the start; my critique simply backs up that skepticism in the scientific record,” he said.

Topological qubits

The ability to create Majorana ‘zero modes’ that resist the errors suffered by traditional qubit-based designs is fundamental to Microsoft’s entire quantum computing strategy, stretching back two decades. This, of course, assumes the existence of subatomic Majorana fermions, named after the Italian physicist who first proposed them in 1937. To this day, they remain only theoretical.

In 2018, Microsoft said its researchers had detected evidence of their existence, an apparently major breakthrough it was forced to retract when the data was successfully challenged. Nature’s editors subsequently backed this up with the blunt note: “The results in this manuscript do not represent evidence for the presence of Majorana zero modes in the reported devices.”

Despite the setback, Microsoft persisted, in 2025 publishing a new paper in Nature that claimed the company had worked out how to exploit the principle in a new “transistor for the quantum age,” the Majorana 1 chip.

Earlier this month, the company launched its successor, Majorana 2, claiming that AI had helped to achieve a 1,000-fold improvement in reliability compared to the earlier chip. “With this progress, the team now expects to achieve a scalable quantum computer by 2029, cutting its original timeline in half,” the company announced.  

However, Microsoft again finds itself on the defensive after the latest criticism from Legg, who said, “I am simply reflecting what most in the field felt from the initial announcement. I felt that I needed to put these concerns into a formal scientific critique. It is good that it has now been peer-reviewed and published.”

His criticism relates to the transport data system, not the raw experimental data itself, which Microsoft had yet to make fully public in a way that would allow independent analysis.

Microsoft still confident

Microsoft said by email that it remains confident that the Majorana has brought usable quantum computing a step closer, pointing to its collaboration with DARPA as part of the Underexplored Systems for Utility-Scale Quantum Computing (US2QC) program.

“We stand by our results and our roadmap,” said technical fellow and vice president of quantum hardware, Dr. Chetan Nayak. “At the end of the day, success is the delivery of a scalable quantum computer. We are confident in our ability to execute against our roadmap.”

“Skepticism and rigor are hallmarks of the scientific process, which we appreciate and have supported from various academics,” he added. “We have participated in dialogue and our thorough rebuttal was accepted and published by Nature.”

Microsoft is not the only company researching quantum computing hardware, with Google, IBM, and Amazon also working on designs. But even if the hardware matures on the schedule claimed by Microsoft,  many believe the gap between technology and implementation inside enterprises could be more of a slow burn than a sudden jump forward.