Strong Spin-Motion Coupling in the Ultrafast Quantum Many-body Dynamics of Rydberg Atoms in a Mott-insulator Lattice

Rydberg atoms in optical lattices and tweezers is now a well established platform for simulating quantum spin systems. However, the possible role of the atoms' spatial wavefunction has not been examined in detail experimentally. Here, we show a strong spin-motion coupling emerging from the large variation of the interaction potential over the wavefunction spread. We observe its clear signature on the ultrafast, out-of-equilibrium, many-body dynamics of atoms excited to a Rydberg S state from an unity-filling atomic Mott-insulator. We also propose a novel approach to tune arbitrarily the strength of the spin-motion coupling relative to the motional energy scale set by trapping potentials. Our work provides a new direction for exploring the dynamics of strongly correlated quantum system by including the motional degree of freedom into the Rydberg simulation toolbox.