Figure 1:

Optical model of the NV centre, example NV-MNP schematic and isolated NV emission spectra (theoretical and experimental). (A) Optical model of the NV center with n + 1 ground states {|g _k⟩} with energies {ℏω _k } (k ∈ {0, …, n}) and two excited states |e ₀⟩ and |e ₁⟩. The state |e ₁⟩ is a phenomenologically defined upper excited level resonant with the angular frequency of incoming radiation ω _d. Other parameters are, spontaneous photon emission rate(s) γ _k , dephasing rate γ _*, ground state phonon decay rate(s) γ _k,k−1, effective excited state phonon decay rate γ _e, and zero phonon line (ZPL) energy ℏω _z. (B) An example dimer setup where the NV-MNP hybrid axis lies along the NV dipolar plane. Optical illumination is polarized along a plane perpendicular to the NV dipolar plane. E ₀ and ${\mathit{d}}_{\text{E}}^{\text{m}+}$ denote the positive frequency amplitudes (coefficients of ${\text{e}}^{-\text{i}{\omega }_{\text{d}}t}$ ) of the external field and the MNP dipole formed by the external field, respectively. E ₀ sin θ/ϵ _effD and ${\mathit{E}}_{\text{sin}\theta }^{\text{m}+}$ denote the screened projections of the external field and the MNP dipole response field onto the NV dipolar plane, at the NV location. (C) The experimentally measured emission spectrum of an isolated NV center in air at room temperature and the fitted Lorentzian sum reported by Albrecht et al. in [18] are denoted by the solid blue and dashed black lines. The output of our extended NV model in (A) implemented as an open quantum system is plotted in red. Individual emission lines are shown with reduced opacity. Both theoretical and experimental spectra including the fitted Lorentzians and the individual emission bands are normalized by the area of the respective total emission curve. The inset conceptually illustrates the NV center embedded in a nanodiamond.