Central Spin Induced Spin Bath Relaxation Dynamics Probed via Hyperpolarization Injection

We report on experiments that quantify the role of a central electronic spin as a relaxation source for nuclear spins in a nanoscale environment. Our strategy exploits hyperpolarization injection from the central spin as a means to controllably probe an increasing number of nuclear spins in the bath, and subsequently interrogate them with high fidelity. We use an ensemble central spin model system in diamond consisting of a nitrogen-vacancy (NV) center surrounded by ∼10^{4 13}C nuclear spins. We observe that the NV center relaxes ¹³C nuclei to a considerable degree within a ∼2nm radius; consequently, distant ¹³C nuclei are measured to have extended transverse state spin lifetimes T₂'>65.5s, extended by close to an order of magnitude in comparison to ¹³C nuclei in close proximity to the NV center. These experiments demonstrate a means to isolate nuclear spins in a nanoscale environment of a central electronic spin, with relevance to quantum memories and sensors constructed out of hyperpolarized nuclei. They also presage interesting new means to measure the extent of spin injection in dynamic nuclear polarization (DNP) experiments.