Abstract
We achieve direct detection of electron hyperfine shifts in individual CdTe/ZnTe quantum dots. For the previously inaccessible regime of strong magnetic fields B_z0.1 T, we demonstrate robust polarization of a few-hundred-particle nuclear spin bath, with optical initialization time of ∼ 1 ms and polarization lifetime exceeding ∼ 1 s. Nuclear magnetic resonance spectroscopy of individual dots reveals strong electron-nuclear interactions characterized by the Knight fields |B_e|50 mT, an order of magnitude stronger than in III-V semiconductor quantum dots. Our studies confirm II-VI semiconductor quantum dots as a promising platform for hybrid electron-nuclear spin quantum registers, combining the excellent optical properties comparable to III-V dots, and the dilute nuclear spin environment similar to group-IV semiconductors.