Computers, as we know them, run on silicon chips. It’s a material we’ve spent trillions of dollars mastering, so it makes sense that scientists want to use that same foundation for the next big leap of quantum computing. The challenge is finding the right “building blocks” within silicon that can handle quantum information without being too difficult to manufacture.

In a study published in Physical Review B, a research team in Professor Chris Van de Walle’s group at UC Santa Barbara identified a new defect in silicon, the CN center.

Replacing Hydrogen With Nitrogen

Quantum bits, or qubits, usually rely on tiny “defects” in a crystal, like a missing atom or a foreign atom sitting where it shouldn’t be.

Until now, a lot of people have been looking at the “T center,” which is made of carbon and hydrogen. It works because it can store information for a long time and communicates using light that travels easily through fiber optic cables. However, hydrogen is tiny, erratic, and moves around during the manufacturing process, making it hard to build reliable devices.

The CN center replaces hydrogen with nitrogen. Kevin Nangoi, a postdoctoral scholar who led the project, explained, “Unlike the T center, this defect does not contain hydrogen and will, therefore, be more robust and easier to realize in actual device.”

Bridging the Gap in Quantum

The team used computer simulations to model how this new defect behaves at an atomic level. These digital tests showed that the CN center does everything the old version could do, just without the stability issues.

“Our results show that the CN center reproduces the key electronic and optical properties that render the T center attractive for quantum applications; in particular, the center is structurally stable and produces light in the telecom range,” said Mark Turiansky, a researcher involved in the project.

By finding a way to skip the hydrogen, the team might have found a shortcut to making quantum tech more scalable.

“If confirmed experimentally, the CN center could serve as a practical new building block for quantum devices, potentially accelerating the development of advanced quantum technologies [while] using the same silicon material that powers today’s electronics,” as Professor Van de Walle concluded.