Exploring cooperative effects with nitrogen-vacancy centres in diamond

We present a theoretical study of superradiance with nitrogen-vacancy centres in nanodiamonds. Superradiance is a radiation phenomenon where identical proximal atoms emit photons collectively. A nitrogen-vacancy centre is an \artificial atom" in which indistinguishability cannot be assumed a priori. Nevertheless, superradiance from nitrogen-vacancy centres in nanodiamond has been observed very recently. While a phenomenological model built on Dicke states and the known properties of nitrogen-vacancy centres was able to explain the experimental findings well, many of the microscopic details that introduce distinguishability were not included: (i) photon emission into orientation-dependent superpositions of polarizations, (ii) transition and permanent dipole-dipole interactions, (iii) random distributions of transition frequencies and spatial locations, and (iv) nitrogen-vacancy centres couple to lattice vibrations. These effects are generally expected to diminish superradiance. In this thesis, we develop numerical simulations based on a model which takes these features into account. Our program can, in principle, perform simulations on the emission dynamics of up to 13 centres. Based on the results presented, we conclude that superradiance persists for certain nitrogen-vacancy centre densities, consistent with the experimental findings. Furthermore, our simulation tools provide a theoretical framework to study coherently driven dynamics, other temperature regimes, or use of other colour centres.