If you’ve followed any of our coverage of quantum computing, you probably know that the biggest challenge is getting quantum states to last very long, especially when moving them around. Researchers at Princeton may have solved this problem as they demonstrate storing qubits in a lab-created diamond. The actual publication is behind a paywall if you want to learn even more.
Generally, qubits are handled as photons and moved in optical fibers. However, they don’t last long in that state and it is difficult to store photons with correct quantum information. The impurities in diamonds though may have the ability to transfer a photon to an electron and back.
Interestingly, this work is somewhat similar to the effort we covered using nitrogen vacancies in diamonds to store data. This type of defect — one where a nitrogen atom replaces a carbon atom in the diamond’s lattice — does store data but doesn’t have the correct optical properties. A silicon vacancy was better optically but was not stable over a long period of time.
Theoretically, a silicon defect in a diamond is electrically neutral, but other nearby defects can change that and cause the silicon vacancy to have an electric charge. Researchers wondered if this spurious charge was spoiling the stability of data storage.
Working with a diamond manufacturing company, they developed a way to purge out additional impurities to form truly neutral silicon vacancies. These vacancies appear to work well for both storing qubits and using and creating photons.
They are still working on a way to interface photonic circuits like those found in quantum computers to the crystal, so the practical application of this technology isn’t going to be immediate. The company that makes the diamonds — Element Six — has a video of some of the technology they use to create engineered diamonds, and you can see it below.
Image credit: Nathalie de Leon lab