Observation of interaction-driven dynamical delocalization in a 1D quantum kicked rotor

The quantum kicked rotor is known to display dynamical localization behavior, which is equivalent to  Anderson localization in momentum space. Although earlier theoretical works have indicated that dynamical localization would be destroyed in the presence of interactions, it has not been experimentally observed thus far. We report on our observation of interaction-driven dynamical delocalization in a 1D quantum kicked rotor as demonstrated by a power-law growth of kinetic energy with kick number. We prepare a quantum kicked rotor system by loading a ¹⁷⁴Yb BEC (a=5.6nm) into 1D tubes formed by a two-dimensional optical lattice derived from a 1073nm laser, and expose the system to a periodically pulsed standing-wave potential. We study the onset of delocalization in the parameter space of kick strength (controlled by pulse parameters) and interaction strength (controlled by number density), and measure the power-law exponent in the delocalized regime. Our observations of interaction-driven delocalization is strongly aided by the elimination of the transverse degrees of freedom in 1D, with the experimental setup allowing continuous tuning and observation from the 3D to the 1D regime, and to the threshold of the Tonks-Girardeau regime.