Observation of Many-body Dynamical Delocalization in a Kicked 1D Ultracold Gas*

In the long-time limit, the classical kicked rotor system displays typical chaos phenomena and diffusive energy growth above a critical kick strength, while its quantum counterpart can exhibit dynamical localization that features energy saturation. However, the behavior of the dynamically localized state in the presence of many-body interactions has long been an open question in the theory realm. Here we report the first experimental study of the many-body effect in dynamically localized quantum kicked rotor (QKR), and our observations of an interaction-driven dynamical delocalization in a 1D ultracold gas of Yb-174 kicked by a pulsed optical lattice. The many-body quantum chaos manifests as a sub-diffusive energy growth in the long-time limit, and our observations shed light on an area that’s difficult to approach from a theoretical perspective.