New Diamond Color Center for Quantum Communication

Color centers in diamond are attractive for quantum communication applications because of their long electron spin coherence times and efficient optical transitions. Previous demonstrations of color centers as solid-state spin qubits were primarily focused on centers that exhibit either long coherence times or highly efficient optical interfaces. Recently, we developed a method to stabilize the neutral charge state of silicon-vacancy center in diamond ($SiV^0$) with high conversion efficiency. We observe spin relaxation times exceeding 1 minute and spin coherence times of $1 ms$ for $SiV^0$ centers. Additionally, the $SiV^0$ center also has $>90\%$ of its emission into its zero-phonon line and a narrow inhomogeneous optical linewidth. The combination of a long spin coherence time and efficient optical interface make the $SiV^0$ center a promising candidate for applications in long distance quantum communication.