Rapid enhanced nuclear spin injection via high-power optical pumping*

Rapid injection of spin polarization into a nuclear bath is a problem of broad interest, with applications spanning quantum information science to dynamic nuclear polarization (DNP). We report on a strategy to boost the spin injection rate by exploiting electrons that can be rapidly polarized via high-power optical pumping. We demonstrate this in a model system of nitrogen vacancy (NV) center electrons injecting polarization into a bath of 13C nuclei in diamond. We innovate an apparatus to deliver large >24W of continuous, isotropic optical power to the sample with a minimal temperature increase, significantly higher than in previous experiments. For spin-ratchet based polarization transfer, we experimentally demonstrate significant boosts in nuclear spin injection rates, increased by close to two order of magnitudes beyond the limit for thermally polarized electrons. Our experiments quantify the the speed limits of polarization transfer in a bulk solid, and identify physical bottlenecks due to electron polarization, electron-nuclear polarization transfer, and spin diffusion. This work suggests intriguing new possibilities for the rapid creation far-from-equilibrium states in hybrid quantum systems.