Diamond engineered to have defects known as ‘vacancy centres’ has potential for use in the routers of a future quantum Internet.
Most research in this area has focused on diamond with nitrogen-vacancy centres, in which one carbon atom is removed and an adjacent carbon atom is replaced with a negatively charged nitrogen ion. Researchers have also experimented with silicon-vacancy centres. These emit photons at more consistent wavelengths than do nitrogen-vacancy centres and thus are potentially better suited for communications along optical fibres, but store information less reliably.
Nathalie de Leon at Princeton University in New Jersey and her colleagues have now created neutral atom-vacancy centres by injecting silicon atoms into highly purified — but boron-doped — diamond. The researchers show that these quantum bits combine the advantages of their predecessors, with both reliable storage and consistent photon emission.