Observation of nanoscale hydrodynamics in a strongly interacting dipolar spin ensemble in diamond --- Experiment*

Bridging the gap between microscopic quantum dynamics and macroscopic emergent phenomena is an important open problem in quantum many-body physics. In this talk, we introduce a novel platform, based upon nitrogen-vacancy (NV) color centers surrounded by a dense ensemble of substitutional nitrogen (P1) centers in diamond, to experimentally probe nanoscale spin diffusion. In this platform, the NV centers serve as both entropy sinks for initializing the P1 ensemble and time-resolved probes of local spin dynamics. Using a combination of static and driven fields, we are able to independently control different parameters such as the strength of interaction and disorder, allowing us to probe the quench dynamics of the strongly interacting spin ensemble under various conditions. We find that the late time dynamics of the P1 ensemble agrees with an effective description based on emergent hydrodynamics, from which we estimate diffusion coefficients.