  Shallow donors in ZnO are promising candidates for photon-mediated quantum
technologies. Utilizing the indium donor, we show that favorable donor-bound
exciton optical and electron spin properties are retained in isolated ZnO
nanowires. The inhomogeneous optical linewidth of single nanowires (60 GHz) is
within a factor of 2 of bulk single-crystalline ZnO. Spin initialization via
optical pumping is demonstrated and coherent population trapping is observed.
The two-photon absorption width approaches the theoretical limit expected due
to the hyperfine interaction between the indium nuclear spin and the
donor-bound electron.
