  Milled nanodiamonds containing nitrogen-vacancy (NV) centers provide an
excellent platform for sensing applications as they are optically robust, have
nanoscale quantum sensitivity, and form colloidal dispersions which enable
bottom-up assembly techniques for device integration. However, variations in
their size, shape, and surface chemistry limit the ability to position
individual nanodiamonds and statistically study properties that affect their
optical and quantum characteristics. Here, we present a scalable strategy to
form ordered arrays of nanodiamonds using capillary-driven, template-assisted
self assembly. This method enables the precise spatial arrangement of isolated
nanodiamonds with diameters below 50 nm across millimeter-scale areas.
Measurements of over 200 assembled nanodiamonds yield a statistical
understanding of their structural, optical, and quantum properties. The NV
centers' spin and charge properties are uncorrelated with nanodiamond size, but
rather are consistent with heterogeneity in their nanoscale environment. This
flexible assembly method, together with improved understanding of the material,
will enable the integration of nanodiamonds into future quantum photonic and
electronic devices.
