Abstract
Group-IV -- Vacancy color centers in diamond are fast emerging qubits that can be harnessed in quantum communication and sensor applications. There is an immediate quest for understanding their magneto-optical properties, in order to select the appropriate qubits for varying needs of particular quantum applications. Here we present results from cutting edge \emph{ab initio} calculations about the charge state stability, zero-phonon-line energies, spin-orbit and electron-phonon couplings for Group-IV -- Vacancy color centers. Based on the analysis of our results, we develop a novel spin Hamiltonian for these qubits which incorporates the interaction of the electron spin and orbit coupled with phonons beyond perturbation theory. Our results are in good agreement with previous data and predict a new defect for qubit applications with thermally initialized ground state spin and long spin coherence time.
Highlights
In recent years, vacancy-impurity defects in diamond have become of high interest and are important because they show great potential in various quantum technology applications
The fine splitting in the ground and excited levels caused by spin-orbit coupling (SOC) is harnessed to realize Λ scheme qubit operation [12]; the spin coherence time of 35 ns is short because of the fast scattering of the electrons between the sublevels in the ground state mediated by the dynamic Jahn-Teller (DJT)
As discussed previously for the SiV defect [4], only the eg orbital appears in the gap which is filled by two electrons with parallel spins in the neutral charge state whereas the a1g and a2u levels fall inside the valence band and the eu level is resonant with it
Summary
Vacancy-impurity defects in diamond have become of high interest and are important because they show great potential in various quantum technology applications. The spin properties of the negatively charged silicon-vacancy [SiVð−Þ] color center [1,2,3,4] with a zero-phonon-line (ZPL) energy at 1.682 eV and S 1⁄4 1=2 spin has recently been studied for qubit applications [5,6,7,8,9,10] As this defect has inversion symmetry (D3d point group), it does not directly couple to an external electric field, and as a consequence, SiVð−Þ possesses narrow [11] inhomogeneous linewidth and negligible spectral diffusion [7,8]. ∼70% of the total emission occurs in ZPL emission [5], with a corresponding Huang-Rhys (HR) factor of 0.3 These properties are promising for realizing solid-state sources of indistinguishable single photons for quantum communication applications [8]. The fine splitting in the ground and excited levels caused by spin-orbit coupling (SOC) is harnessed to realize Λ scheme qubit operation [12]; the spin coherence time of 35 ns (see Refs. [7,13]) is short because of the fast scattering of the electrons between the sublevels in the ground state mediated by the dynamic Jahn-Teller (DJT)
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