select search filters
briefings
roundups & rapid reactions
Fiona fox's blog
A study published in Nature looks at Microsoft Azure Quantum on measuring topological qubits.
Professor George Booth, Professor of Theoretical Physics at King’s College London, said:
What is the significance of this work?
“Companies have typically measured their progress in terms of qubits, or quantum units of information that they compute and by this measurement Microsoft have lagged behind others. However, they have instead focused on the long-game by working on a system which is inherently more resilient to noise and interference – using so called ‘topological’ qubits. This noise resilience could pay off in the long term, as processing quantum information (rather than the classical bits that traditional computers work with) is inherently fragile.
These topological qubits protect the information they carry by using the properties of a new type of “emergent particle, a Majorana fermion, which means that it is harder for this information to be lost as it is processed. However, this added layer of complexity when constructing these qubits when compared to competing architectures.
“This work demonstrates progress on measuring these topological qubits, which is an essential operation to realise the potential of these devices. They stop short of unambiguously demonstrating that they can measure a full topological qubit but get closer to a viable topological qubit.
What does it mean for progress in quantum computing?
“There is no doubt that having competition between scientific platforms for quantum computing compounds the probability that (at least) one will emerge as a viable platform. This is a step in the direction of a very different platform that could compete with the more mature technologies pioneered by the likes of Google. There is still a significant way to go from here in demonstrating that the technology can be scaled up, but Microsoft is bullish about their roadmap for the future.
“Ultimately, the importance of this work will probably only be able to be judged in hindsight, if and when the technology reaches maturity compared to other platforms. However, it is certainly an impressive technical achievement, demonstrating control over these emergent particles at the most fundamental levels.
Is this good quality research? Are the conclusions backed up by solid data? How does this work fit with the existing evidence?
“It is a highly technical paper, and works hard to present the scientific facts without hyperbole. They are cautious, likely since Microsoft have been burnt before by their claims of developing topological qubits in a paper which had to be later retracted after scientific flaws were pointed out. In this work, they are much more tempered about their conclusions that they are actually measuring a topological qubit, but present the evidence that it is at least highly likely.”
Have the authors accounted for confounders? Are there important limitations to be aware of?
“The work is clearly seen by all as a step on a long road and not an ending point. Within the paper, it even takes care not to overstate the implications of the work, or even the certainty by which they have measured a topological state.
“I think that for many in the field there is still some healthy scepticism of the timescales for the roadmaps of some of these tech companies towards a quantum computer that is routinely solving practical problems, but this paper demonstrates that fundamental hurdles are being overcome. Whether a claim of ‘years’ is accurate will remain to be seen.
What are the implications in the real world? Is there any overspeculation?
“The end goal of this line of research is a ‘universal’ quantum computer. This would be able to simulate certain problems much faster than classical supercomputers would ever be able to.
“Of these problems where a speedup can be demonstrated, certain ones are causing the most interest and are likely driving the investment. Namely, these are breaking encryption protocols, chemical simulations to design new drugs and materials, and solving certain ‘difficult’ optimisation problems, like a logistical supply chain issue.
“These are not problems that most people have to tackle on a day-to-day basis, so they will likely always be specialist machines for these jobs and not something that most people would have or need access to. However, there is significant commercial interest in these activities, and therefore a significant payoff to the company who can develop the viable technology first.”
Prof Paul Stevenson, School of Mathematics and Physics, University of Surrey, said:
“Microsoft have pioneered the idea of so-called “topological qubits” as the basic building blocks of future quantum computers, but so far have failed to demonstrate working devices while competitors have been building basic quantum computers for a few years now using other qubit technology. What Microsoft are counting on is that their devices, once realised, will be naturally much more robust by design than the somewhat temperamental competing technologies. Their latest result shows that they have managed to build roughly one half of one qubit. Now the challenge is to build that up first into a single qubit, then an array of qubits, at which point they will be very serious competitors in the field. The new papers are a significant step, but as with much promising work in quantum computing, the next steps are difficult and until the next steps have been achieved, it is too soon to be anything more than cautiously optimistic.”
‘Interferometric Single-Shot Parity Measurement in InAs-Al Hybrid Devices’ by Morteza Aghaee et al. was published in Nature at 16:00 UK time on Wednesday 19 February 2025.
Declared interests
Professor George Booth:
Prof Paul Stevenson: I am funded for my research by direct UK government research council grants, and grants from AWE, part of MOD. I am a member of UK Government research council funding and advisory panels and a UK delegate to the NuPECC European Nuclear Physics committee