Diffusion Measurements in a Strongly Correlated Lattice Gas

Ultracold lattice gases are an excellent platform for studying the transport properties of quantum systems. We present near-equilibrium transport measurements for a thermally active Mott insulator composed of bosonic ⁸⁷Rb confined in a cubic optical lattice. A small selection of atoms at the center of the gas are “tagged” by transferring them to a different spin state. This process uses tightly focused laser beams to induce stimulated Raman transitions without distorting the density profile. The spatio-temporal dynamics of the tagged atoms are measured using spin-resolved imaging. The effect of temperature on the dynamics is measured by varying the entropy per particle of the gas before loading into the lattice.