Microsoft’s claims about progress toward a practical quantum computer are again under scrutiny after a peer-reviewed critique in Nature raised doubts about a February 2025 paper that underpins the company’s Majorana-based approach. The new analysis, published by a University of St. Andrews lecturer, questions whether the software Microsoft described can reliably identify the tiny conductive gap the company says is crucial for creating more stable qubits.
Quantum computers, which the critique notes could tackle problems beyond classical machines in science and cybersecurity, have become a national priority. The U.S. administration has directed significant funds into the field and issued targets for a scientific quantum system by 2028, while Microsoft has publicly said it expects a working quantum system by 2029.
What the Nature critique says
Henry Legg, a lecturer in quantum physics at the University of St. Andrews, authored the formal critique. Legg reviewed the February 2025 Nature paper and an associated press announcement and concluded that Microsoft’s software produced inconsistent results and misreported outcomes. According to Legg, a broader dataset Microsoft released but did not include in the paper showed what appeared to be random noise rather than a clear signal of the claimed gap.
"If you’re looking into something which is essentially just random physics, eventually you will find the Jesus in your toast," Legg said, using that analogy to describe the risk of finding spurious patterns when probing large datasets.
Legg’s critique does not seek retraction of the February 2025 paper, but it directly challenges the evidence presented in that publication and the integrity of the software analysis described there. The paper is described in the public record as central to many of Microsoft’s subsequent quantum efforts.
Microsoft’s response and program status
Microsoft issued a formal reply in Nature defending its claims and characterizing the code as a "practical tuning tool" designed to locate promising sites on chips for placing qubits. In an interview, Chetan Nayak, who oversees Microsoft’s quantum hardware efforts, said the software functions well enough that the company regularly uses it to configure chips currently carrying out quantum computing operations.
"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 has maintained that its overall research program is making practical progress despite external concerns. The company has also publicly claimed to have found the Majorana particle - a theoretical subatomic entity central to its quantum strategy - though that specific discovery has not been published in a peer-reviewed journal.
Context: prior retractions and editor flags
The company’s quantum work has attracted skepticism before. Two Microsoft-backed papers were previously retracted from Nature, and editors issued alerts about potential research problems in two other papers, one in Nature and another in Science. Microsoft has stated that the retracted Nature papers were produced outside its own labs and that the company did not review the data before those publications.
External expert perspective
Sergey Frolov, a physicist at the University of Pittsburgh who has also criticized Microsoft’s approach, emphasized the absence of a sequence of reliable experiments that would support the Majorana-based route. He contrasted Microsoft’s situation with that of rivals whose approaches do not depend on the existence of the Majorana and which, he said, have more longstanding experimental support.
"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," Frolov said. "On the contrary, we have a series of papers that keep being challenged at the very basic level, by different people."
Why the February 2025 paper matters
The Nature paper in question made a narrower, technical claim compared with Microsoft’s broader public statements. It reported that software was able to identify a minute gap in an otherwise highly conductive wire - a gap that Microsoft argues is relevant to producing qubits with longer coherence times. Qubits are powerful but fragile; their quantum state often collapses in fractions of a second. Identifying a stable gap in a conductive wire is, according to Microsoft, part of a process that could deliver more durable qubits.
Legg’s analysis contends that the publicly released extended dataset does not corroborate the gap. He described Microsoft’s published outcomes as inconsistent and the broader data as effectively random noise, which, if accurate, would weaken the experimental basis for subsequent development steps that rely on those findings.
Implications and open questions
The exchange highlights ongoing tensions between ambitious corporate timelines for quantum hardware and the scientific community’s demand for reproducible, peer-reviewed evidence. Microsoft stands by its research and its tools' utility in ongoing chip configuration and experimentation. Critics continue to press for clearer, independently verifiable evidence, particularly for work that underpins strategic technical choices tied to Majorana-based architectures.
Given the paper’s role in Microsoft’s program and the recent Nature critique, the debate over data interpretation and reproducibility is likely to continue while the company pursues its stated timeline toward a working quantum system.