Small Steps Lead to Big Changes in Quantum Computing

Dozens of companies are working on quantum computing. These groups range from small startups to massive technology giants. They are all trying to find a viable path to utility. Public discourse often focuses on new technologies and major landmarks. This can obscure the fact that significant success is built on incremental progress. Any major breakthrough relies on a steady foundation of smaller achievements.

In recent weeks, several companies released progress reports. These reports detail their efforts to bring quantum technologies closer to general use. None of these updates represent a major breakthrough in isolation. However, all of them are absolutely necessary for the technology to advance. The goal of these reports is to convey the hard work required to move the field closer to something truly useful. The path to quantum utility is not a straight line. It is a series of small, necessary steps.

Microsoft is one of the few companies working on topological qubits. This system is based on distinct physics that occurs when particles are confined. Microsoft’s approach relies on a thin superconducting wire placed on top of a semiconductor. In superconductors, groups of two electrons form Cooper pairs. However, if the wire contains an odd number of conducting electrons, there will be a single unpaired electron. This unpaired electron ends up delocalized to both ends of the wire. This behavior is dictated by the strange rules of quantum mechanics.

Theorists had described this behavior before. But Microsoft had to confirm that the physics occurred as predicted before it could build qubits based on it. The road was not smooth. Some early work in this area was later retracted. Microsoft’s attempts to demonstrate solid physics were met with skepticism. The system they were showcasing was very noisy. Despite these challenges, the company laid out a roadmap based on building qubits out of pairs of these nanowires.

This week, the company released an update. It reported much better performance by changing the materials used to make its qubits. In its earlier hardware version, the company used aluminum as a superconductor. It kept the devices near absolute zero. They replaced the aluminum with lead. The underlying semiconductor was also reformulated. It now includes tin. This improved the spin-orbit coupling between electrons in the lead and those in the semiconductor.