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He thinks next week's APS meeting won't settle the matter, for two reasons. One is that he thinks Microsoft got the science wrong.

"So we kind of know that it's not going to be a concern-killer presentation, based on that [private briefing to select scientists]," Frolov said. "And as a physicist, there's just absolutely no way that qubit that they're claiming can work because a topological qubit requires Majorana and without Majorana you cannot have it.

"If all your Majorana results are scrutinized and criticized, there is just absolutely no way this is going to be a topological qubit. That leaves kind-of one option, that it's ... an unreliable presentation. And that's why I say fraud because at this point I'm out of other words to use."

His other reason is that he thinks the format of next week's APS meeting won't allow for scrutiny of Microsoft's claims. In a letter to the APS, he criticizes its organizers for not inviting critics of Microsoft to deliver a talk.

The letter goes on to challenge APS to disclose payments received from Microsoft, and to notify attendees of the APS Global Physics Summit about community concerns regarding the software giant's claims.

He also wants Microsoft to share comprehensive data about its research, to facilitate corrections if needed.

[...] Legg's beef with Microsoft is that the mega-corp relies on tests that don't work.

"There's many problems with this ... so-called Topological Gap Protocol," the St Andrews lecturer explained. "And ultimately it doesn't give any information about the actual physics that's going on in these devices. It ends up that it's sensitive to things like measurement ranges."

That matters because, in Legg's telling, Microsoft's topological claims rest on a 2023 paper [PDF] by the IT giant's researchers published in the journal Physical Review B (PRB).

Legg thinks that older paper is "the basis for all of these [new] claims" but that the two pieces of research use different measurement ranges for reasons that aren't explained in Microsoft's latest research.

Legg is also concerned that code used for the protocol described in the older PRB paper differs from code in Microsoft's latest research. The software giant's changing definition of "topological" also worries him.

"They had the definition of topological and then they adjusted it," he said. "They diluted it basically to something which is almost meaningless and certainly meaningless when it comes to constructing a topological qubit."

The issue Microsoft faces, Legg explained, is similar to the issue that caused the biz's researchers to retract their 2018 paper – which he claims became necessary because the behavior it described wasn't evidence of Majorana particles, just a description of disorder.

"So the point is that the systems that they're looking at are still just as disordered, there's no obvious improvement in the quality of the devices.

"The only improvement there has been is in the quality of the PR campaign, or certainly the level of the claims that they're making. And I would say almost everyone in the field agrees with that."

The Empire Strikes Back

Except Microsoft. Asked to respond to Legg's paper, a Microsoft spokesperson provided this comment from Nayak: "There is a century-old scientific process established by the American Physical Society for resolving disputes. Comments and author responses are reviewed by referees in the journal and eventually published for the benefit of readers. We have not been contacted by the PRB [Physical Review B] editors to respond to Legg's comment. When we are, we will provide an official response."

Nayak challenged Legg's argument as an attack on a false straw man and summarized his responses thus.

1. Protocol vs. Code: Legg claims there's a difference between our described protocol and the implemented code. This is incorrect, so this is a non-issue.
2. Measurement Ranges: He accuses us of manipulating measurement ranges to get desired outcomes. This is false. The ranges come from an initial scan we describe, and we always analyze the full data.
3. Experimental vs. Simulated Data: He points out a minor difference in how we analyze experimental and simulated data. This does not affect our results.
4. Topological Regime Requirement: He complains that we relaxed the requirement for how deep into the topological regime the system needs to be. The original requirement was stated in an unpublished manuscript. In our published paper "InAs-Al Hybrid....", we clearly stated that we instead adopted a widely accepted minimal definition of topological which has appeared in multiple published works by a number of independent academic groups.

A Microsoft spokesperson offered a lengthier comment:

This is a very exciting time for quantum computing. Utility-scale quantum computers are just years away, not decades. To enable this future, Microsoft is building an error-corrected, utility-scale quantum computer based on a compact superconducting topological qubit architecture. For the last 20 plus years we have been collaborating with leading researchers and scientists worldwide to bring this vision to life. We recently achieved two very important milestones.

The first was validation of our approach from DARPA, and the second was our unveiling of the Majorana 1 chip, a significant breakthrough for us and the industry.

Others are working to bring this same vision to life, but with different approaches. This is what makes science fun.

Some in the field believe an alternative approach is the right one to take and have invested significant time and resources into their methods. We understand why they would want to advocate for their approach.

Discourse and skepticism are all part of the scientific process. That is why we are dedicated to the continued open publication of our research, so that everyone can build on what others have discovered and learned. In fact, we brought over 100 scientists and physicists together recently to spend the day with us going over our research.

Following our announcement, we have received some general questions about our methodology. While the Nature paper outlined our approach, it does not speak to our progress. The Nature paper was submitted on March 5, 2024, and published on February 19, 2025.

Almost an entire year has passed, and during that time tremendous progress has occurred. For example, since our submission on March 5, 2024, we have fabricated a two-sided tetron and both nanowires were tuned into the topological phase via the topological gap protocol. This is the topological qubit configuration: there are 4 Majorana zero modes (MZMs), one at each end of each topological nanowire. We have performed both Z and X measurements. These are the basic native operations in a measurement-based topological qubit.

There is a lot of science to explain when it comes to quantum computing, and in the coming weeks and months, we look forward to sharing our results along with additional data behind the science that is turning our 20 plus year vision for quantum computing into a tangible reality.

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Original Submission