Theory of optical Λ transitions in the 15N-V- center in diamond: Role of the hyperfine interaction

We present a thorough derivation of the excited-state energy levels of the negatively charged N-15-V- center in diamond for the strong applied electric-field case. We show that in the N-15-V- center a spin nonconserving two-photon Lambda transition exists that is mediated by the hyperfine interaction, which provides the possibility to write quantum information. Using second-order perturbation theory we obtain a Lambda transition rate of the order of 10 MHz at room temperature, which allows for approximately 104 quantum logic operations within the spin coherence time tau(d)(T=300 K) approximate to 1 ms of the N-15-V- center.