A Physicist Just Published a Stinging Takedown of Microsoft's Quantum Breakthrough Claims in Nature

Microsoft says it will have a working quantum computer by 2029. It says its latest chip is 1,000 times more reliable than anything it built before. It says the underlying physics — a theoretical particle called the Majorana — is real and measurable.

A physicist at the University of St Andrews disagrees. And he said so in Nature.

On June 24, 2026, Dr. Henry Legg published a formal critique in Nature's "Matters Arising" section — the journal's dedicated venue for scientific challenges to previously published research. The paper accuses Microsoft of flawed software, code errors, omitted data, and results that appear to show random noise rather than the quantum breakthrough the company claims.

It is the fifth time Microsoft's quantum computing work has faced serious scientific challenge. And this time, the critique landed three weeks after Microsoft unveiled its most ambitious chip yet.

What Microsoft Claimed — and When

The story begins with Majorana. This is a theoretical type of quasiparticle that Microsoft has spent nearly two decades trying to prove exists. The theory matters because Majorana-based "topological qubits" could, if real, build quantum computers far more resistant to errors than current approaches.

In February 2025, Microsoft published a paper in Nature claiming its software could detect a critical gap in a superconducting wire — a gap the company says is a necessary precursor to building a topological qubit. Then in June 2026, at its Build conference in San Francisco, Microsoft unveiled Majorana 2 — its second-generation quantum chip.

The Majorana 2 announcement was striking on several levels. The chip swapped the aluminium superconductor from its predecessor for lead — an unusual choice that Microsoft said AI tools helped make viable. Lead dissolves in water, making it extremely difficult to use in chip manufacturing. Microsoft said it solved that problem.

The result, the company claimed, was a 1,000-fold improvement in qubit stability. Qubits on Majorana 2 now hold their quantum state for about 20 seconds on average, with some lasting up to a minute. The original Majorana chip managed milliseconds.

On the back of that announcement, Microsoft accelerated its roadmap. The company had previously said useful quantum machines were years away. Now it named a year: 2029.

What Dr. Henry Legg Found

Legg's June 24 Nature critique targets the software tool Microsoft used to validate its February 2025 Nature paper — the analytical foundation beneath the entire Majorana claim.

He found three specific problems. First, the software yielded "inconsistent and misreported outcomes." Second, it contained code errors. Third, a broader dataset that Microsoft released publicly but did not include in the Nature paper showed random noise — no clear evidence of the topological gap the company claimed to find.

Legg described the problem with a vivid analogy. Finding a signal in random data by searching long enough, he said, is like finding an image of Jesus in toast by looking through an entire bakery's worth of loaves. "If you're looking into something which is essentially just random physics, eventually you will find the Jesus in your toast," he said.

His conclusion was direct: Microsoft has not demonstrated the basic physics needed for even a single topological qubit.

"In short: Microsoft haven't demonstrated the basic physics needed for even a single topological qubit," Legg wrote.

On the implications for the company's 2029 roadmap, he was equally blunt. "They simply cannot sell the 2029 roadmap as credible to the public when the underlying physics is not there," he said.

Microsoft's Response

Microsoft did not accept the critique quietly. The company published a formal rebuttal in the same issue of Nature — on the same day Legg's paper appeared.

In its response, Microsoft defended the software as a "practical tuning tool" rather than a scientific proof mechanism. Chetan Nayak, Microsoft's Technical Fellow and Corporate Vice President for Quantum Hardware, told reporters the code works well enough that the company uses it routinely to set up chips now running actual quantum operations.

He used an analogy of his own. "It's almost like arguing, is flight possible or not? And then you're standing next to an airplane," Nayak said. "Well, why don't you hop in and take a ride?"

Microsoft also pointed to an external validation it said matters: the company has advanced to the final phase of DARPA's Quantum Benchmarking Initiative — a US Defense Advanced Research Projects Agency programme evaluating quantum computing progress. DARPA moved Microsoft into that final phase, the company said, after independently evaluating both public and proprietary results using a team of highly qualified experts.

"We stand by our results and our roadmap," Nayak said.

Jason Zander, executive vice president of Microsoft Quantum, added a different framing. "Bell Labs didn't have to prove there was an electron to invent the transistor," he said during a press briefing. "We did have to prove that Majorana and that theory was actually real."

A Pattern That Goes Back Years

What makes Legg's June 2026 critique especially significant is that it is not the first. It is not the second. It is not even the third or fourth.

This is the fifth serious scientific challenge Microsoft's quantum work has faced.

In 2018, Microsoft researchers published a paper in Nature claiming evidence of a Majorana zero mode — the signature quasiparticle at the heart of the company's approach. That paper was retracted in 2021 after the data was found to be incomplete.

The journal Science subsequently flagged possible research problems in a 2020 Microsoft study. Nature editors flagged concerns about another Microsoft paper. Two retracted papers and two flagged papers add up to a research record that critics say should give the scientific community serious pause.

Microsoft has said the retracted papers were produced outside its main labs and it had not reviewed the underlying data before publication. That explanation has not satisfied everyone.

"Neither Microsoft nor anyone else has laid a foundation where it is clear that these Majorana-based advances are plausible, through a series of reliable experiments," said Sergey Frolov, a physicist at the University of Pittsburgh who has also studied and criticised Microsoft's quantum research.

On the Majorana 2 preprint specifically, Frolov was sharper still. "This new preprint is not based on a research track record that can be considered a solid foundation."

What Topological Qubits Are — and Why They Matter

To understand why this dispute matters, it helps to understand what Microsoft is attempting.

Current quantum computers use qubits — the quantum equivalents of classical bits — that are extraordinarily fragile. They lose their quantum state in fractions of a second when disturbed by heat, vibration, or electromagnetic interference. This is called decoherence. It is the central engineering problem limiting what quantum computers can currently do.

Most companies — IBM, Google, IonQ, Quantinuum — build qubits using superconducting circuits or trapped ions and then apply quantum error correction in software to compensate for the fragility of individual qubits.

Microsoft is attempting something fundamentally different. Its approach relies on topological qubits. In theory, a topological qubit encodes quantum information not in a single physical location but across a pair of Majorana quasiparticles at opposite ends of a nanoscale wire. Because the information is spread out rather than localised, it is inherently more protected against local disturbances.

If topological qubits work as theorised, Microsoft could build quantum computers with far fewer error correction overheads. Some estimates suggest Microsoft's approach could eventually squeeze millions of qubits onto a single chip — a potential scale advantage over rivals.

The catch is that nobody has confirmed that Majorana quasiparticles exist in a useful form in the real structures Microsoft builds. That is precisely what the scientific dispute is about.

The Majorana 2 Chip and the 2029 Deadline

The timing of Legg's critique is pointed. It arrives three weeks after Microsoft announced the Majorana 2 chip and its 2029 quantum roadmap — the most specific commercial commitment the company has ever made on quantum computing timelines.

Until June 2026, Microsoft had refused to name a target year. It said only that useful quantum machines were a matter of years, not decades. The Majorana 2 announcement changed that. The 2029 date puts Microsoft directly alongside IBM, which has its own 2029 quantum timeline and last month committed $10 billion to quantum chip manufacturing.

The Majorana 2 chip itself is physically distinct from its predecessor. The core superconducting layer uses lead instead of aluminium. The active semiconductor region uses indium arsenide with indium arsenide antimonide. Microsoft used AI-assisted materials discovery to make the lead layer viable during manufacturing.

The company claims qubits on the chip hold their state for 20 seconds on average — vastly longer than the milliseconds of the first Majorana chip. Some qubits reportedly held their state for up to one minute.

Even taking those figures at face value, Majorana 2 remains a single-device prototype. The path from 20-second qubit stability to a fault-tolerant quantum computer requires two-qubit operations, quantum error correction, logical qubits, and scaling to thousands or millions of physical qubits. Microsoft has not demonstrated any of those subsequent steps.

What Rivals Are Doing Instead

The contrast between Microsoft's approach and its competitors sharpens the stakes of this debate.

IBM builds quantum computers using superconducting qubits it has been refining for over a decade. Its qubits are well understood by the broader physics community. Independent researchers around the world can replicate and build on IBM's published results. IBM has already demonstrated quantum advantage for specific problem types.

Quantinuum uses trapped ion qubits — individual charged atoms held in electromagnetic traps. This approach also has a long record of peer-reviewed validation and independent replication.

Google uses superconducting qubits and published a landmark quantum advantage demonstration in 2019 that has been widely examined and largely accepted by the physics community, even where the specific claims were debated.

Microsoft's topological approach, by contrast, rests on a foundation that the broader physics community has repeatedly questioned. Frolov's assessment captures the difference bluntly: "When Microsoft is mentioned these days, physicists and quantum computing specialists just chuckle or raise their eyebrows."

The Peer Review Problem

One specific issue that runs through the entire Microsoft quantum controversy is the relationship between press releases and peer-reviewed science.

Microsoft's February 2025 Nature paper made a narrower claim than the company's simultaneous press release. The Nature paper said Microsoft had developed software to identify a gap in a superconducting wire. The press release described the world's first chip powered by topological qubits capable of leading to quantum computers that could solve meaningful problems in years, not decades.

Nature's editorial team added a note to the published paper explicitly stating that the results do not represent evidence for topological modes — only a platform for potentially manipulating such modes in the future.

The Majorana 2 results, released in June 2026, were published as a preprint — meaning they have not yet been through peer review. The prior preprint from Majorana 1 remained unpublished as of June 2026, which Frolov cites as evidence that top journals likely rejected it.

Legg put the peer review question in the starkest terms possible: "If this was from any other group or Ph.D. student, it would never make it through peer review."

The Larger Stakes

This is not a dispute confined to physics conferences and academic journals. Quantum computing has become a national security priority.

The Trump administration invested $2 billion in quantum research and set a goal of a scientific quantum system by 2028. DARPA's Quantum Benchmarking Initiative — the programme whose final phase Microsoft has entered — exists precisely because the US government wants independent verification of which quantum claims are real and which are not.

The cryptocurrency industry is also watching closely. A sufficiently powerful quantum computer could theoretically break widely used public-key cryptography. Bitcoin is considered particularly vulnerable because quantum computing could allow an attacker to derive private keys from exposed public keys. Legg's critique does not rule out that future risk, but it directly challenges the evidence Microsoft cites for approaching it.

For now, the debate sits precisely where it has been sitting since 2018: Microsoft makes a claim, physicists push back, and the company advances a roadmap that its critics say rests on physics that has not been proven.

The airplane analogy Nayak offered is compelling. But critics point out that the Wright Brothers had to actually fly first.

Key Facts at a Glance

• Critique published: June 24, 2026, in Nature's "Matters Arising"
• Author: Dr. Henry Legg, physicist, University of St Andrews
• Target: Microsoft's February 2025 Nature paper on topological qubit detection software
• Legg's findings: Flawed tune-up procedures, code errors, omitted data, results consistent with random noise
• Microsoft chip announced: Majorana 2, unveiled June 2, 2026, at Microsoft Build, San Francisco
• Majorana 2 claim: 1,000-fold improvement in qubit stability; 20-second average qubit lifetime
• Key material change: Lead superconductor replacing aluminium, aided by AI-assisted materials discovery
• Microsoft's 2029 target: Scalable, practical quantum computing
• DARPA status: Microsoft advanced to final phase of Quantum Benchmarking Initiative
• Previous retractions: Two Microsoft-backed Nature papers retracted; two others flagged
• Key critics: Dr. Henry Legg (St Andrews), Dr. Sergey Frolov (University of Pittsburgh)
• Microsoft defence: Formal reply published in same Nature issue; DARPA validation cited
• US government investment: $2 billion in quantum research; goal of scientific quantum system by 2028