Scientist publishes fresh doubts over Microsoft's quantum claims

A UK-based physicist has published fresh doubts over Microsoft's quantum computing claims, asserting that a software tool used to validate the company's research contained coding errors and lacked sufficient accuracy [1]. Dr Henry Legg, a long-term critic of Microsoft's quantum work, detailed his concerns in a paper published by the journal Nature [1]. He argued that the tech giant has still not proven it has created a theoretical quasi-particle called Majorana, which underpins its approach to quantum computing [1]. "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," Legg said [1]. Microsoft has stood by its results. Dr Chetan Nayak, Technical Fellow and Corporate Vice President of Quantum Hardware at Microsoft, responded to the criticism. "At the end of the day, success is the delivery of a scalable quantum computer," Nayak said [1]. He added that the company's thorough rebuttal was accepted and published by Nature [1]. In that response, Microsoft states that the software Legg referred to did not "interpret" the measurements which led to its conclusions [1]. The dispute centers on the extreme fragility of current quantum machines, which are prone to errors from the slightest interference such as small vibrations or a tiny change in temperature [1]. Microsoft has pursued an unusual path to overcome this, basing its approach on a 90-year-old physics theory involving a state of matter that is neither liquid, solid, nor gas [1]. The company recently released a second generation of its Majorana chip, which it says is 1,000 times more reliable than the previous one [1]. Legg also accused Microsoft of not sharing enough data for other scientists to scrutinise [1]. Microsoft said it is sharing all of its data with the US defense agency Darpa for independent arbitration but has claimed some of it is too commercially sensitive to publish more widely [1]. Darpa, originally created in 1958 in response to the Soviet launch of Sputnik, is a research and development agency of the United States Department of Defense responsible for developing emerging technologies [6]. The agency has a history of using prize competitions to spur innovation by opening challenges to novel approaches from the public [7]. This is not the first time Microsoft's quantum research has been called into question. A paper from a Microsoft-backed lab which claimed to have found evidence of the Majorana particle was retracted in 2021 [1]. In 2025, Nature's editors added a note to a subsequent Microsoft paper claiming to have created the particle itself, writing, "The results in this manuscript do not represent evidence for the presence of Majorana zero modes in the reported devices" [1].