Properties of Donor Qubits in ZnO Formed by Indium-Ion Implantation

Neutral shallow donors (D0) in ZnO have emerged as a promising candidate for solid-state spin qubits. Here we report on the formation of D0 in ZnO via implantation of In and subsequent annealing. The implanted In donors exhibit optical and spin properties on par with those of in situ–doped donors. The inhomogeneous linewidth of the donor-bound-exciton transition is less than 10 GHz, comparable to the optical linewidth of in situ In. Longitudinal spin relaxation times (T1) exceed reported values for in situ Ga donors, indicating that residual In-implantation damage does not degrade T1. Two-laser Raman spectroscopy of the donor spin reveals the hyperfine interaction of the donor electron with the spin-9/2 In nuclei. This work is an important step toward the deterministic formation of In-donor qubits in ZnO with optical access to a long-lived nuclear-spin memory.