Uncovering long coherence times in the nitrogen vacancy centers of hexagonal diamonds

Nitrogen-vacancy (NV) centers in cubic diamonds — a type of defect where a nitrogen atom substitutes a carbon atom neighboring a lattice vacancy — have commonly been studied for applications in quantum sensing and computing. Kumar et al. investigated NV centers in hexagonal diamonds and identified a configuration with markedly enhanced spin coherence. In other words, this configuration “keeps its ‘quantumness’ for a longer amount of time,” said author Gabriel Kumar.

The hexagonal form of diamond, known as lonsdaleite, had been successfully synthesized by experimental researchers in 2025, nearly sixty years after their first observation in the Canyon Diablo meteorite.

“In short, there was a new form of diamond and we asked the question: If we put a defect in it, does it behave differently [than in ordinary diamond]?” said author Giulia Galli. “And we actually discovered that it can be better.”

Using first-principles computations, the authors studied two defect configurations, one with symmetry identical to that of the NV center in cubic diamond, and another with reduced symmetry. Density functional theory, quantum defect embedding theory, and generalized cluster-correlation expansion were used to compute the electronic and coherence properties of NV centers in hexagonal diamond and compare them with those of NV centers in cubic diamond.

The authors showed that while the electronic properties and functionality of the reduced symmetry configuration were similar to that of an NV center in cubic diamond, the spin coherence had a predicted improvement.

“We found this configuration to have a longer coherence time, which is about four times that of NV centers in cubic diamond,” said author Victor Wen-zhe Yu. “This qubit is also less sensitive to small magnetic noises, which makes it promising for quantum sensing and quantum communications.”

Source: “Nitrogen-vacancy centers in hexagonal diamond exhibit long coherence times,” by Gabriel Kumar, Siyuan Chen, Victor Wen-zhe Yu, and Giulia Galli, Applied Physics Letters (2026). The article can be accessed at https://doi.org/10.1063/5.0355148 .