Silicon challenges diamond for quantum computing crown

Regular readers may remember the nitrogen vacancy in diamond turning out to be a useful "defect", because even at room temperature it could maintain a spin state for long enough to function as quantum memory.

This neat trick prompted researchers to go hunting for similar behaviour around defects in other semiconductors, and now it looks like they’ve found one – in silicon carbide.

According to a letter in Nature, researchers at the Center for Spintronics and Quantum Computation, University of California, Santa Barbara, have demonstrated that a defect spin state in a particular form of silicon carbide (the 4H polytype of SiC (4H-SiC) – since you ask) "can be optically addressed and coherently controlled in the time domain at temperatures ranging from 20 to 300 kelvin".

The researchers used optical and microwave techniques similar to those used with diamond nitrogen–vacancy qubits, to probe the silicon carbide defects, and found a world that seems to be set up for commercial exploitation. The defects are optically active near telecommunications wavelengths, and exist in materials that have well established and industrial scale fab-techniques.

"This makes them promising candidates for various photonic, spintronic and quantum information applications that merge quantum degrees of freedom with classical electronic and optical technologies," the researchers write.

Watch this space.