Probing nanoscale local thermalization in a 2D dipolar spin ensemble on the surface of diamond

We observe remarkably slow local spin dynamics in a two-dimensional disordered many-body dipolar spin system, formed by naturally-occurring electronic spins on the surface of a diamond crystal. Shallow NV centers are used to probe individual spins. We characterize the strength of dipolar interactions among the surface electronic spins and measure the on-site disorder. We observe slow spin transport at the level of single-spin correlation functions and can quantitatively explain our observations with a time-dependent disorder resonance counting theory.