Preparing single SiV− center in nanodiamonds for external, optical coupling with access to all degrees of freedom oleh Stefan Häußler, Lukas Hartung, Konstantin G Fehler, Lukas Antoniuk, Liudmila F Kulikova, Valery A Davydov, Viatcheslav N Agafonov, Fedor Jelezko, Alexander Kubanek