Microsoft upgrades controversial quantum chip — researchers are still sceptical

Majorana 2 is Microsoft’s latest topological quantum computer chip.Credit: John Brecher for Microsoft

Microsoft has unveiled an upgraded quantum chip that it says keeps the company on track to develop practical quantum computers faster than its competitors. The chip, called Majorana 2, is an updated version of the highly controversial Majorana 1 chip that was unveiled last year. But some researchers continue to be sceptical of the company’s claims.

Details of Majorana 2 were shared in a preprint posted on arXiv on 2 June1. The paper, which is yet to be peer reviewed, reports that the chip’s qubits — a quantum computer’s equivalent of a computer’s bits — are able to hold information for more than 20 seconds, which is 1,000 times longer than the qubits in its predecessor. But some researchers question whether the company has demonstrated that it has built a quantum computer at all.

“In this paper, there’s nothing that shows that this is a qubit,” says Henry Legg, a theoretical physicist at the University of St Andrews, UK.

“I believe this is just another step in Microsoft’s almost a decade long track record of publishing unreliable results,” says Vincent Mourik, an experimental physicist at the Research Centre Jülich in Germany.

In February 2025, Microsoft researchers published a research paper in Nature2, which described experiments on a chip that had been designed to store qubits in ‘topological’ states of matter.

Microsoft has worked for years to obtain these topological ‘Majorana zero modes’ — quantum states that arise from the collective behaviour of the electrons in a micrometre-long, H-shaped device. The topological qubits are supposed to be more robust to noise and errors than are competing qubit technologies. Microsoft expects that improved noise protection in its chips will make topology‑based machines easier to build at scale.

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