Microsoft鈥檚 recently revealed quantum computer was dealt another blow this week, as data presented by the firm at the world鈥檚 biggest annual gathering of physicists failed to convince researchers that the device works as advertised.
鈥淭hanks for waking up early and coming out today. I appreciate you all in the back,鈥� said at Microsoft, opening his presentation at the American Physical Society (APS) Global Summit in Anaheim, California, on 18 March. His 8am talk, trailed as providing key new data about Microsoft鈥檚 controversial Majorana 1 chip, was so well-attended that the conference鈥檚 organisers had to remind people not to sit in the aisles.
All quantum computers use quantum bits, or qubits, to process information. These can be constructed in various ways, and in Microsoft鈥檚 quantum computing technology they are supposedly based on a type of exotic quasiparticle called a Majorana zero mode (MZM). This is a big deal, since MZMs can theoretically be used to create a kind of qubit called a topological qubit, which would be less likely to introduce errors into calculations than other forms of the technology. Being error-prone is one of the biggest challenges holding quantum computing back, making topological qubits incredibly attractive to researchers.
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But whether Microsoft has truly made topological qubits has been a bone of contention since it announced the new chip last month. The firm responded to critics by promising it would share more data at the APS meeting. In his talk, Nayak presented previously unseen experimental data on implementing logic gates 鈥� basic mathematical operations used to program a quantum computer 鈥� on a device with two MZM-based topological qubits, a smaller version of the Majorana 1 chip. 鈥淣ow we have something that we can iterate and improve upon, that鈥檚 the most exciting part,鈥� he said. In his view, these advances have moved topological quantum computing away from being a basic science and closer to engineering a quantum computer.
But when Nayak opened the floor for questions, the response in the room was muted. 鈥淚鈥檇 have loved for this [data] to have just come out screaming at me, but I don鈥檛 think that鈥檚 what I see,鈥� said at Cornell University in New York, who noted that it was unclear whether measurements concerning the gates really proved that they worked. Nayak says that those measurements match his team鈥檚 theoretical modelling of the device and don鈥檛 decrease their confidence in the device鈥檚 performance.
鈥淚f this was the first experiment in this field, it would be impressive,鈥� at the University of Basel in Switzerland told 快猫短视频. However, researchers have been trying to unambiguously detect MZMs in devices similar to Microsoft鈥檚 for over a decade without success, which, in his view, diminishes the firm鈥檚 results. 鈥淚t鈥檚 true that these are not new problems, but we are taking them head on,鈥� says Nayak. 鈥淲e have a lot of confidence in continued progress.鈥�
at the University of New South Wales in Sydney told 快猫短视频 that while the new measurements are still very far from what would be needed for a practical quantum computer, the advances in device fabrication that Microsoft鈥檚 team has made are commendable. Much of the trouble with MZMs lies in manufacturing issues, she says. Experimental signatures of material imperfections and disorder have previously been mistaken for proof of MZMs, leading to several high-profile retractions of journal papers proclaiming to have found the elusive particles, including by Microsoft.
Though Nayak spoke about minimising the amount of disorder in the two-qubit device extensively, Loss says that, in his view, such imperfections are still influencing it significantly. 鈥淚 know they are trying very hard, but the challenges are enormous,鈥� says at Princeton University.
Yet Microsoft believes that these challenges are surmountable, and Nayak stands by the firm鈥檚 approach, including a procedure that was used to determine whether MZMs are present in the device or not. This method 鈥� the 鈥渢opological gap protocol鈥� 鈥� was the subject of another heavily attended APS presentation where at the University of St Andrews in the UK criticised it in depth. Based on his analysis of computer code and data that Microsoft made available in the past, he again raised the possibility that the protocol is mistaking effects of disorder for MZMs, and that it is too unreliable to be used for building practical devices.
Speaking to 快猫短视频 after his talk, Nayak says that it may never be possible to totally eliminate any chance of this, but that his team鈥檚 protocol makes such misidentifications very unlikely. Some of his conviction derives from extensive simulations and materials science analysis that the firm isn鈥檛 able to share with the public for reasons of protecting intellectual property, he says. 鈥淲e have to protect our IP, but it鈥檚 all up for discussion.鈥� The team has a clear sense of how to move forward, he says.
鈥淭his approach [to quantum computing] may very well have its strengths and weaknesses. Currently it has a lot of weaknesses, but it also has a lot of promise,鈥� Kim told 快猫短视频. 鈥淣one of the hopes have been dashed, but they have not yet been fulfilled.鈥�
