Quantum technologies utilise the unique phenomena of quantum superposition and entanglement to encode and process information, with potentially profound benefits to a wide range of information technologies from communications to sensing and computing.
However a major challenge in developing these technologies is that the quantum phenomena are very fragile, and only a handful of physical systems have been identified in which they survive long enough and are sufficiently controllable to be useful. Atomic defects in materials such as diamond are one such system, but a lack of techniques for fabricating and engineering crystal defects at the atomic scale has limited progress to date.
A team of scientists demonstrate, in a paper published in Optica (“Laser writing of individual nitrogen-vacancy defects in diamond with near-unity yield”), the success of the new method to create particular defects in diamonds known as nitrogen-vacancy (NV) colour centres. These comprise a nitrogen impurity in the diamond (carbon) lattice located adjacent to an empty lattice site or vacancy.
The NV centres are created by focusing a sequence of ultrafast laser pulses into the diamond, the first of which has an energy high enough to generate vacancies at the centre of the laser focus, with subsequent pulses at a lower energy to mobilise the vacancies until one of them binds to a nitrogen impurity and forms the required complex.

Image Credit:  RUB, Marquard

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