Wavepacket dynamics of coupled particles in aperiodic chains: Weakening of Anderson localization and local field effects

We study the wavepacket dynamics of two interacting particles under an aperiodic potential that can be continuously tuned from a pseudo-random to a uniform regime. Assuming an on-site Hubbard interaction, we show that the influence of interaction is not strong enough to change the characteristic aperiodicity that signals the emergence of extended states. However, we unveil that the inter-particles interaction promotes a weakening of Anderson localization that is more prominent at intermediate couplings. The wavepacket dynamics in the regime presenting extended eigenstates show an oscillatory motion of the centroid while the wavepacket widens. We explain in detail the origin of these oscillations and discuss the characteristics of the Bloch oscillations of the two-particles wavepacket by exploring the relevance of bounded states to the dynamics of pair formation.