Effect of the nanopillar diameter on diamond silicon vacancy center spin lifetime

Color centers in diamond micro and nano-structures play an important role in a wide range of quantum technologies. However, obtaining high-quality color centers in small structures is challenging, as properties such as spin population lifetimes can be affected by the transition from a bulk to nanostructured crystal host. In this manuscript, we measure how population lifetimes of silicon vacancy center orbital states change when they are created in nanopillars whose diameters vary from 1 µm to 120 nm. We also discuss the influence of annealing methods on the silicon vacancy inhomogeneous linewidth. After selecting a sample with low inhomogeneous broadening and patterning it with nanopillars, we expected that restricted vibrational modes in the smallest structures could extend spin population lifetimes. However, we found that this effect was masked by other effects that reduced population lifetimes, suggesting that imperfections in the crystal lattice or surface damage caused by etching can influence SiV spins.