  The nitrogen-vacancy (NV) centre, as a promising candidate solid state system
of quantum information processing, its electron spin coherence is influenced by
the magnetic field fluctuations due to the local environment. In pure diamonds,
the environment consists of hundreds of C-13 nuclear spins randomly spreading
in several nanometers range forming a spin bath. Controlling and prolonging the
electron spin coherence under the influence of spin bath are challenging tasks
for the quantum information processing. On the other hand, for a given bath
distribution, many of its characters are encoded in the electron spin
coherence. So it is natural to ask the question: is it possible to 'decode' the
electron spin coherence, and extract the information about the bath structures?
Here we show that, among hundreds of C-13 bath spins, there exist strong
coupling clusters, which give rise to the millisecond oscillations of the
electron spin coherence. By analyzing these oscillation features, the key
properties of the coherent nuclear spin clusters, such as positions,
orientations, and coupling strengths, could be uniquely identified. This
addressability of the few-nuclear-spin cluster extends the feasibility of using
the nuclear spins in diamond as qubits in quantum computing. Furthermore, it
provides a novel prototype of single-electron spin based, high-resolution and
ultra-sensitive detector for the chemical and biological applications.
