Physicists at UC Santa Barbara have discovered a quality of silicon carbide — a material commonly used in the manufacture of semiconductors — that can be used to perform quantum computing.
Silicon carbide is a compound that has some 250 crystalline forms, but its 4H polytype (pictured below right) has an imperfection that traps electrons. The spin of these electrons can then be manipulated and measured (addressed) with optical wavelengths. In short, silicon carbide is an array of solid-state, addressable qubits.
The big news is silicon carbide traps electrons at room temperature, and (so far) the only other material to exhibit this property is diamond. Unlike diamond, silicon carbide crystals can be grown at an industrial scale and relatively cheaply. Also, the qubits in silicon carbide can be addressed using optical wavelengths already used in telecommunications.
“Our dream is to make quantum mechanics fully engineerable,” said William Koehl, a graduate student in the Awschalom lab. “Much like a civil engineer is able to design a bridge based on factors such as load capacity and length span, we’d like to see a day when there are quantum engineers who can design a quantum electronic device based on specifications such as degree of quantum entanglement and quality of interaction with the surrounding environment.”
While silicon carbide could be used to make a standalone quantum computer, it is more exciting to think of systems that combine optical circuits, transistor switching, and quantum mechanics. With some more work, we might see CPUs “now with added qubits!” or optical routers that use qubits for crazy, quantum-oriented probabilistic algorithms that conventional computers just can’t do. No one really knows what quantum computing will ultimately entail or enable — but now that scientist have found a material that provides affordable qubits at room temperature, we’re a lot closer to finding out.