  Near transform-limited single photon sources are required for perfect photon
indistinguishability in quantum networks. Having such sources in nanodiamonds
is particularly important since it can enable engineering hybrid quantum
photonic systems. In this letter, we report the generation of optically stable,
nearly transform-limited single silicon vacancy emitters in nanodiamonds. Lines
as narrow as 325 MHz are reported, which is comparable to the lifetime limited
linewidth. Moreover, the emitters exhibit minimal spectrum diffusion and
absolute photostability, even if pumped well above saturation. Our results
suggest that nanodiamonds can host color centers with supreme properties
suitable for hybrid photonic devices and quantum information.
