Coupling single bright spins with channels of intermediate dark spins in diamond

The nitrogen-vacancy (N-V) center in diamond has garnered interest as a room-temperature solid-state system not only for exploring electronic and nuclear spin phenomena but also as a candidate for spin-based quantum information processing. Recent experiments reveal the coupling of a single bright electron spin of an N-V center to small numbers of dark electron spins of nitrogen defects in its immediate vicinity, not otherwise detected in luminescence \footnote{R.J. Epstein, F.M. Mendoza, Y.K. Kato and D.D. Awschalom, \textit{Nature Physics} \textbf{1}, 94 (2005)}. We explore the possibility of utilizing this magnetic dipole coupling between bright and dark spins to couple two spatially separated single N-V center spins by means of intermediate dark nitrogen spins. The angle-resolved magneto-photoluminescence microscopy technique is extended to simultaneously detect a pair of single N-V centers a few microns apart.