Microsoft has just wrapped up 20 years of research on Majorana fermions, subatomic particles that could help create a million-qubit quantum computer. This journey involved building topological qubits, which promise more stability and less need for error correction.
A recent paper highlights a fascinating property of Majorana fermions: they can act as their own antiparticle. Matthias Troyer, a Microsoft technical fellow, explained that when you take two of these particles and bring them together, they might annihilate completely or coexist without vanishing. This gives them a unique ability to signify binary states—“0” when they annihilate and “1” when they remain.
Krysta Svore, another technical fellow, shared that they’ve designed a chip called Majorana 1. This chip can measure the presence of these particles, crucial for building reliable and controllable topological qubits. These unique particles can conceal quantum information, making it tougher to measure but also more robust. Microsoft has crafted a new measurement method precise enough to differentiate between one billion and one billion and one electrons in a superconducting wire, essential for confirming qubit states.
Svore emphasized that this new design overcomes typical noise issues that lead to qubit errors, a hurdle for quantum computing. With these topological qubits, they are creating a fresh quantum architecture called the topological core, capable of scaling to a million qubits on a small chip. Each atom is intentionally placed—it’s like building a picture one brush stroke at a time, she noted.
Unlike traditional processors that use electrons, Svore stated, “We use Majoranas.” Majorana 1 is a compact quantum chip that integrates qubits with control electronics. It operates within a dilution refrigerator, which keeps qubits at extremely low temperatures, much colder than outer space. Alongside this, Microsoft has also developed the necessary software stack to run quantum applications.
This chip fits easily in the palm of your hand and can be installed in Azure data centers. Zulfi Alam, a Microsoft vice president, explained the setup: a quantum accelerator works alongside a classical machine, transitioning between classical and quantum processes depending on the task.
Once calculations wrap up, the results are synthesized on the classical machine, providing solutions to various problems. The researchers are optimistic about scaling Majorana 1, a critical challenge in quantum computing. Microsoft’s architecture uses aluminum nanowires arranged in an “H” shape, with controllable Majoranas linked to each qubit. These Hs can also connect across the chip.
“It’s complex because we had to demonstrate a new state of matter, but after that, it’s fairly simple,” Svore said. “It tiles out, leading to a straightforward architecture that promises faster scaling.”