Thermalization in Isolated Quantum Systems with Dipole-Dipole Interactions

Isolated systems of interacting cold atoms are expected to thermalize under the Eigenstate Thermalization Hypothesis (ETH). Exceptions to the ETH, such as the presence of quantum many-body scar states, could be revealed experimentally by studying the dynamics that arise from dipole-dipole interactions among ultracold Rydberg atoms in a magneto-optical trap. We calculate the final equilibrium state and measure the final time-evolved state in experiment. We find that while the numerical and experimental equilibration are in good agreement, both deviate from the expected thermal state calculated using dynamical typicality. This failure to thermalize persists over a large range of densities.