Microsoft's Majorana 2 Reports 20-Second Parity Lifetimes; Critics Want More
· TexaHub · Quantum
Microsoft says a lead-based materials stack made its topological qubits 1,000 times more reliable, but its preprint shows only Z-parity data and has not been peer reviewed.
What Microsoft announced
Microsoft unveiled Majorana 2, the second generation of its topological quantum chip, at its Build conference in San Francisco on 2 June [4]. The company says the chip's qubits are 1,000 times more reliable than those of its previous processor, with lifetimes that exceed 20 seconds and occasionally exceed one minute, against 1 to 12 milliseconds before [2].
The main change is in materials: the superconductor has moved from aluminium to lead, and Microsoft says the topological gap that is meant to protect the qubits has more than doubled [2]. An analysis of the release puts the gap at roughly 70 µeV, up from about 30 µeV, and notes that the substrate also changed, from InP to GaSb [5]. On the strength of this progress, Microsoft now targets a scalable quantum computer by 2029, which it describes as cutting its original timeline in half [1].
Microsoft also tied the result to its Build AI messaging, saying agentic AI from its Microsoft Discovery platform automated a measurement process that had previously taken weeks per cycle and helped manage fabrication [1]. Zulfi Alam, corporate vice president for quantum, said that "using agentic AI to automate the measurements was a game changer" [1].
What the data shows
The supporting preprint, titled "20 Second Parity Lifetime in an InAs--Pb Tetron Device", was posted to arXiv on 2 June [3]. It reports a characteristic parity switching time of about 20 seconds, with some instances reaching minute scale, measured on one tetron's hybrid nanowire within a multi-tetron array [3].
That scope is the crux of the debate. The paper presents only Z measurements, while demonstrating a qubit requires both X and Z measurements [4]. The PostQuantum analysis adds that there is no peer review yet, no gate, entanglement or algorithm demonstration, and no evidence of reproducibility across devices [5]. Henry Legg of the University of St Andrews told Science News that "nothing in the presented data proves the existence of a topological qubit", while Kartiek Agarwal of Argonne National Laboratory called the work "fantastic progress" [4].
The split mirrors the reception of Majorana 1 in 2025, when Legg and Sergey Frolov of the University of Pittsburgh dismissed the X-measurement data presented at the time and Agarwal saw "very many positive signs" [6].
Why it matters
In our reading, a parity lifetime of seconds would be a meaningful materials result even if the topological interpretation remains contested, because a longer lifetime is a precondition for low-error parity measurements. The 2029 target, however, rests on steps Microsoft has not yet shown publicly: a convincing X measurement, two-qubit operations and repeatable devices. Until peer-reviewed data on those steps appears, the roadmap date is best treated as a company aspiration rather than a forecast.
Sources
[1] Introducing Majorana 2: How Microsoft's new quantum chip was made 1,000x more reliable with the help of Microsoft Discovery's agentic AI — Microsoft, 2 Jun 2026
[2] Majorana 2: Microsoft's scalable quantum processor with reliable, long-lasting qubits — Microsoft Quantum, undated
[3] 20 Second Parity Lifetime in an InAs--Pb Tetron Device — arXiv, 2 Jun 2026
[4] Microsoft's quantum chip got an upgrade. Critics are still skeptical — Science News, 2 Jun 2026
[5] Microsoft Majorana 2: 20-Second Qubits, Same Questions — PostQuantum, 3 Jun 2026
[6] Physicists are mostly unconvinced by Microsoft's new topological quantum chip — Science News, 27 Mar 2025