  Optically-detected paramagnetic centers in wide-bandgap semiconductors are
emerging as a promising platform for nanoscale metrology at room temperature.
Of particular interest are applications where the center is used as a probe to
interrogate other spins that cannot be observed directly. Using the
nitrogen-vacancy center in diamond as a model system, we propose a new strategy
to determining the spatial coordinates of weakly coupled nuclear spins. The
central idea is to label the target nucleus with a spin polarization that
depends on its spatial location, which is subsequently revealed by making this
polarization flow back to the NV for readout. Using extensive analytical and
numerical modeling, we show that the technique can attain high spatial
resolution depending on the NV lifetime and target spin location. No external
magnetic field gradient is required, which circumvents complications resulting
from changes in the direction of the applied magnetic field, and considerably
simplifies the required instrumentation. Extensions of the present technique
may be adapted to pinpoint the locations of other paramagnetic centers in the
NV vicinity or to yield information on dynamical processes in molecules on the
diamond surface.
