On Tuesday, Microsoft physicist Chetan Nayak faced a formidable challenge: convincing an excited but largely skeptical standing-room audience of other scientists that his company had shaken the landscape of quantum computing. Nayak tried to make the case that his team had created the world’s first “topological” qubit, a potential robust quantum analog of the 0-or-1 bit that powers a conventional digital computer. Doing so would require not only conjuring the long-sought Majorana quasiparticle—a proposed mode of electron behavior never before confirmed—but also controlling multiple Majoranas on an actual platform to encode quantum information.
Many audience members, however, remained largely unsold. “I don’t think the data are convincing,” says Jelena Klinovaja, a physicist at the University of Basel who attended Nayak’s talk at the American Physical Society’s (APS’s) Global Physics Summit. “It is difficult to be convinced from the presented data that one is really dealing with a topological [qubit].”
And just the day before at the same meeting, Henry Legg, a physicist at the University of St. Andrews who had already posted two preprints challenging the company’s work, attacked further. “It doesn’t look like Majoranas, at least to me,” Legg said at a Monday session. “Any company claiming to have a topological qubit in 2025 is essentially selling a fairy tale [that] undermines the field of quantum computation … and public confidence in science.”
For his part, Nayak remained collected and convinced that his team has tamed the elusive Majoranas, even as Legg and other physicists denounce Microsoft’s claims. “We’ve only revealed a tiny fraction of what we’ve done,” Nayak tells Science. “It’s going to look more and more convincing that this is going to be the basis of a technology.”
The furor began last month, when Microsoft proclaimed via a press release and a paper in Nature what it deemed a major breakthrough in its quantum computing research: a chip hosting eight of these Majorana-based topological qubits, which it says would pave the way for utility-scale computing devices in “years, not decades.” The paper, however, didn’t detail the chip or provide proof of Majoranas, focusing instead on a method for measuring certain quantum properties on a future device. Still, over the following days, quantum computing stocks rose, and Senator Ted Cruz (R–TX) touted the chip on the Senate floor.
Microsoft CEO Satya Nadella responded to Elon Musk’s congratulations on X: “We think this could be quantum’s transistor moment.” Meanwhile, many physicists were outraged by the splashy announcement, posting fiery online comments, livestreamed takedowns, and social media memes.
“I’ve never seen anything like this in my time in physics,” says Jason Alicea, a physicist at the California Institute of Technology. “It’s certainly the strongest claim by far that’s ever been made in [this field] … and the burden is on them to really show that what they have is the real deal.”
For 40 years, scientists have dreamed of better simulating nature and solving certain classes of problems much faster by building computers that operate on not on conventional bits—which can be set to either 0 or 1—but rather on qubits, which can be set to combinations of 0 and 1 simultaneously. But quantum computers remain in their infancy, stifled by their qubits’ fragility to environmental noise.
Microsoft, taking the road less traveled, is attempting to build qubit protection directly into its hardware. Its basic strategy is to make qubits out of Majoranas, which are essentially delocalized electrons. Because the electrons don’t exist in any one location, their information is protected “topologically” from any local disturbances—if there’s a sufficiently large “gap” between the nearest energy states the electrons could jump to.
Microsoft’s current chip design features arrangements of ultrathin, superconducting indium-arsenide wires that force the electrons inside to form loosely tied pairs. Under the right conditions, the wire can also accommodate an extra unpaired electron, which essentially splits in half to occupy a Majorana at each end of the wire. The wire’s two “parity” states—which would represent a 0 or 1 in a future computer—correspond to whether it contains an even or odd number of electrons. By performing certain measurements on the system, Nayak and his Microsoft colleagues plan to shift and probe the parity of the wires, thereby encoding and reading out quantum information.
But over the past 2 decades, the Majorana has proved as slippery as its namesake, the Italian physicist who mysteriously disappeared in 1938. The field has suffered from unexpected engineering hurdles, empty promises, and repeatedly debunked claims.
To establish a more systematic benchmark for spotting Majoranas, Microsoft researchers devised a protocol in 2021 that establishes a series of experimental tests for assuring that the device is in the proper topological phase to host them. They built a computer simulation of the device that they trained to identify a topological phase, and then they fed measurements of the real device to the same protocol to assess whether it’s also in the right state.
In 2023, Nayak’s team claimed to have created a device that passed the protocol. The new paper, published in Nature on 19 February, establishes a procedure for determining the parity of the nanowires—thus reading out the state of the system. Microsoft claimed these results, along with new measurements hinted at in an accompanying press release, constituted “the world’s first quantum processor powered by topological qubits.”
Researchers in the field appreciate that the Microsoft team is attempting to hunt for Majoranas in a more methodical manner—but condemn the team for rolling out what they say are overblown claims. “The announcement was rooted in just a fundamentally different definition of what it means for me to make a topological qubit,” says Alicea, who publicly outlined a list of experiments needed to execute to persuade him.
A week after Microsoft’s February announcement, Legg posted his first challenge, a preprint criticizing the company’s protocol used to identify Majoranas. By digging into the available code, he noticed that simply changing the range over which different parameters, such as magnetic field, were measured appeared to affect whether a device passes as topological. In addition, within one experiment, the code used to evaluate the real data seems to be less restrictive than the code used for simulated data, Legg notes. He believes these issues undermine the reliability of the test—and thus invalidate the recent claim. “It’s based on an entirely flawed protocol,” Legg says. “They have some explaining to do.”
In a LinkedIn post last week, Microsoft researcher Roman Lutchyn countered Legg’s complaints, arguing that the protocol’s sensitivity to parameter changes is “expected and does not invalidate the use of the protocol with the correctly chosen parameters.” Regarding the different versions of the code, Lutchyn points out that the discrepancy is “statistically insignificant”—yielding only one false positive for 700 regions of interest.
In a second preprint posted last week, Legg also critiques the raw conductance data in Microsoft’s latest Nature paper, which he claims appear far too disordered to be in the right state. Following Legg’s talk at the APS summit, Lutchyn stood by his team’s protocol and measurements, which he says cannot be explained without the system being in the right phase. “What we have done here is both theoretically correct and practical,” he told Legg during the Q&A session. “If you have a better idea [for finding Majoranas] put forward a protocol, and then let’s all follow it.”
Anton Akhmerov, a physicist at the Delft University of Technology, calls some of Legg’s concerns about the protocol “very much valid,” although he does not think they completely nullify Microsoft’s work. “In order for the community to trust that the outcome of the protocol is reliable, these absolutely need to be studied systematically,” he adds.
During the APS talk on Tuesday, Nayak presented the promised new details of a device that combines two nanowires into an H-shaped array that’s meant to demonstrate a functioning qubit. The new measurements aim to compare the parity of Majoranas across the two linked nanowires, probing their ability to exist in two distinct states that are complex combinations of 0 and 1—essential for the device to operate as a qubit.
Some in the audience were impressed by the apparent material advances that enabled this double-nanowire device. However, the measurements were met with more skepticism. Nayak showed data that suggested a single nanowire would hold the 0 or 1 state for up to 10 milliseconds. But the data on the two more complex states were far less clear. A statistical analysis suggested these states persisted for a few microseconds, but some physicists argued the data looked more like noise. “I would have loved for this to come out screaming at me that there’s only two [distinct] states,” says Eun-Ah Kim, a physicist at Cornell University who moderated the session. “But that’s not what I think I see.”
To many physicists, Microsoft has yet to present solid evidence of Majoranas, let alone a coupled system that behaves convincingly like a qubit. Still, Steve Simon, a physicist at the University of Oxford, holds onto hope that the results will stand. He bet Legg a Belgian beer that Nature wouldn’t retract Microsoft’s paper within the next 2 years. “Lack of great evidence doesn’t mean it’s not there,” Simon says. “It could be that their protocol actually isn’t that reliable, but that doesn’t mean they didn’t land in the right place anyway.”
Given the field’s rocky history, though, many researchers are disgruntled by both Microsoft’s sensational announcement and the aggressive backlash to it. “The problem is that both sides are making confident claims … and I don’t think either viewpoint is justified,” Akhmerov says. “It’d be nice if people would chill out a bit.”
