Strongly Coupled Diamond Spin Qubits by Molecular Nitrogen Implantation

Abstract

Ionized nitrogen molecules (${}^{15}$N${}_2^{+}$) are used as efficient point sources for creating NV${}^{-}$ pairs in diamond with nanoscale spatial separation and up to 55 kHz magnetic coupling strength. Co-implantation of ${}^{12}$C${}^{+}$ increased the yield of pairs, and a ${}^{13}$C-depleted diamond allowed 0.65 ms coherence times to be obtained. Further coupling to a third dark spin provided a strongly coupled three spin register. These results mark an important step towards realization of multi-qubit systems and scalable NV${}^{-}$ quantum registers.