Microsoft's 2025 Quantum Breakthrough Challenged by Peer-Reviewed Nature Critique Citing Python Errors

A peer-reviewed critique published in Nature has challenged Microsoft's 2025 quantum computing breakthrough, alleging that the company's claims of controlling Majorana particles were undermined by basic Python coding errors and omitted data. Dr. Henry Legg, a lecturer at the University of St Andrews, published the analysis on June 24, 2026.

Legg's critique focuses on Microsoft's Topological Gap Protocol (TGP), a software tool designed to detect the phase transition necessary for quantum calculations using Majorana particles. He argues that Microsoft's tune-up software contained two fundamental Python errors that concealed alternative results from peer reviewers.

Specific coding errors identified

According to Legg, Microsoft's plotting code was hardcoded with a filter that displayed only the single largest purportedly topological region. Changing the filter from zbp_cluster_numbers=[1] to zbp_cluster_numbers=[1,2] reveals a second region that passed the protocol. Additionally, the code antisymmetrized bias voltage based on array index rather than physical value, effectively reversing a Python array by index position instead of actual bias voltages.

• Microsoft's original 2025 paper claimed a topological superconductor could enable a meaningful quantum computer in years, not decades.
• Legg states that raw transport data omitted from the original publication indicates considerable disorder incompatible with a topological gap.
• Microsoft inaccurately told peer reviewers that only one region passed the TGP within the explored range, according to Legg.
• Microsoft responded that the bugs were minor and stands by its findings and roadmap.
• Legg told The Register that his feeling is Microsoft is centuries, not decades, away from a topological quantum supercomputer, if it works at all.

Implications for quantum computing credibility

The critique raises questions about the peer review process for high-profile quantum claims. Microsoft's Majorana 1 chip, unveiled in February 2025, was hailed as a milestone that could accelerate the timeline for fault-tolerant quantum computers. If Legg's analysis holds, it would mean the foundational evidence for that roadmap is flawed.

Microsoft has not provided a detailed rebuttal to the specific coding errors but maintains that its research is sound. The company's quantum roadmap continues to target a topological quantum supercomputer within years. Legg's critique, however, suggests that the underlying physics may not support Microsoft's claims, and that the company's software errors obscured negative results. The broader quantum computing community will now scrutinize both the original data and Microsoft's response to determine the validity of the breakthrough.