Material-barrier tunnelling in one-dimensional few-boson mixtures

We study the quantum dynamics of strongly interacting few-boson mixtures in one-dimensional traps. If one species is strongly localized compared to the other ( e. g., much heavier), it can serve as an effective potential barrier for that mobile component. Near the limit of infinite localization, we map this to a system of identical bosons in a double well. For realistic localization, the backaction of the light species on the 'barrier' atoms is explained-to lowest order-in terms of an induced attraction between these. Even in equilibrium, this may outweigh the bare intra-species interaction, leading to unexpected correlated states. Remarkably, the backaction drastically affects the inter-species dynamics, such as the tunnelling of an attractively bound pair of fermionized atoms.