New paper questions Microsoft's quantum computing breakthrough claims
A physicist argues that Microsoft's Majorana 1 chip did not convincingly demonstrate a topological qubit, casting doubt on its quantum computing roadmap.
A critique published in Nature on Wednesday challenges the fundamental technology behind Microsoft's Majorana 1 quantum chip, which the company unveiled in February 2025. Microsoft claimed the chip featured topological qubits, a novel approach expected to provide error-resistant quantum computing.
Henry Legg, a physicist at the University of St Andrews, reanalyzed Microsoft's data and concluded that the researchers did not convincingly demonstrate a working topological qubit. According to theory, electrons in Microsoft's semiconductor-superconductor wire should form a collective pattern called a Majorana particle. However, Legg argues that the observed signals could arise from quantum dots—electron-containing structures—rather than Majorana particles, which would be useless for quantum computing.
Microsoft's team published a rebuttal in Nature, dismissing Legg's critique as not a substantial scientific challenge. Chetan Nayak, head of Microsoft's quantum team, stated that Legg has not proposed an alternative model fitting all their data. Legg originally posted his analysis on arXiv in February 2025, but peer review took a year.
Meanwhile, Microsoft announced Majorana 2 in June, claiming next-generation topological qubits and aiming for a scalable quantum computer by 2029. Legg says the new chip's data suffers from similar issues.
