Doubling down on controversial claims, Microsoft accelerates quantum computing plans

Even in a hype-drenched field, the claim seems bold: Tech giant Microsoft announced today it plans to build a useful quantum computer in just 3 years—half the time it had previously cited. The schedule can accelerate, Microsoft researchers say, because of improvements to the building block of their technology: a microscopic device called a topological qubit. “We’ve talked about a scalable quantum machine on the 2033 timescale, and we believe that these kinds of accelerations can bring that into 2029,” Chetan Nayak, the physicist who leads Microsoft’s quantum computing effort, said in an online press conference last week. But critics maintain that the paper reporting the improved qubit lacks evidence that the device actually works. “The Microsoft Quantum project follows a sustained pattern of unreliable claims, so the new ones are not surprising,” says one of the most vociferous doubters, Sergey Frolov, a physicist at the University of Pittsburgh. A quantum computer would exploit strange quantum phenomena to solve certain problems that would overwhelm any conventional supercomputer. Whereas a conventional computer employs bits that can be set to 0 or 1, a quantum computer manipulates qubits that can be set to 0 and 1 simultaneously. Thanks to those superposition states, a quantum computer can analyze many inputs at once, with the wavelike quantum states interfering to cancel out wrong solutions and cause the right one to pop out. In principle, a qubit can be any quantum system with two states to denote 0 and 1. Scientists have fashioned qubits out of tiny circuits of superconducting metal resonating with unquenchable currents, individual atoms, lone ions, and single photons. Most qubits’ delicate quantum states quickly fuzz out when exposed to noise from the environment. That’s one reason why today’s quantum computers contain at most a few hundred qubits. To obtain more-robust qubits, Microsoft researchers have been pursuing a particular byzantine design. On a chip made up of semiconducting layers, they lay down a strip of superconducting metal, which induces a wirelike region of superconductivity in the underlying semiconductor.

Electrons pair up in this region, and a tiny electrode called a quantum dot can inject an additional, unpaired electron. “Within one of these wires we’ve got an even or odd number of electrons, maybe 10 million versus 10 million and one,” Nayak says. The state with no lone electron signifies 0, and the state with one signifies 1. Microsoft researchers read out the states by measuring the wire’s capacitance with another nearby quantum dot. In theory, quantum effects should make those states particularly robust. Weirdly, the lone electron is delocalized so it exists at every location along the wire at once, making it harder to disturb. In addition, the unusual shape of the quantum state describing a pair of electrons reduces the chances a pair will interact with its environment—the topological aspect of the device. Reports of such delocalized electron states—which are known as Majorana zero modes—have come and gone over the years. In February 2025, Microsoft researchers reported, to intense controversy, that they had achieved Majorana states in devices fashioned by laying down traces of superconducting aluminum on the microchip. Those states persisted for about 2 milliseconds before flipping, the researchers claimed. Now, they have replaced aluminum with lead to increase the strength of the binding of the pairs in the semiconductor, and the key quantum states last 20 seconds, Nayak says. That’s long enough to put a full-fledged quantum computer within reach, he says. Critics aren’t buying it. Achieving the Majorana states requires applying a strong magnetic field along the wirelike region and precisely tuning a voltage that controls the density of electrons in it. Microsoft researchers have not shown they can tune into the rare, desired state, says Henry Legg, a physicist at the University of St. Andrews. Rather, he says, the data suggest the system is settling into a quiet spot in a landscape of noise. Moreover, he says, there is a simpler explanation for the switching behavior the Microsoft team is seeing. To control and read out a nanowire, they use a number of quantum dots surrounding it. The switching behavior they see could just be an electron hopping on and off a quantum dot, perhaps one formed incidentally by part of the wirelike region, Legg says. “This is exactly what you could get from a quantum dot.”

Even assuming the Microsoft researchers have achieved the Majorana states, there’s no evidence their device actually works as a qubit, Legg and Frolov say. For a practical qubit, researchers need to control the device and ease it into different admixtures of its two states. But the new paper contains no such demonstration. Legg also notes that the endurance time Microsoft quotes does not necessarily equal how long a superposition will last. Nayak acknowledges that Microsoft researchers have been cagey with their peers in the past. “We said just trust us, we’re going to make the topological phase more robust,” he says. “Now, we’re revealing more about how we’ve been doing that.” He says Microsoft researchers also have data, albeit unpublished, that show they can fully control their qubits and can even run quantum algorithms on their chip. That “trust us” approach rankles other scientists. “You go to a conference and somebody mentions Microsoft and people are chuckling,” Frolov says. “It’s become a joke and it’s terrible for the field.” To achieve a scalable quantum computer in 3 years, Microsoft researchers would likely need to have a prototype running in the lab now, he says. Based on the results they published so far, that scenario is “implausible,” Frolov says. Legg thinks the Microsoft researchers have convinced themselves of conclusions their data do not support. “At this point, I think that this is less the realm of reality and headed to something more like a quasi-religion.” By Microsoft researchers’ own scheduling, judgment day will arrive quite soon.