Conductance transition with interacting bosons in an Aharonov-Bohm cage

We study the transport of interacting bosons through an Aharonov-Bohm cage-a building block of flatband networks-with coherent pump and sink leads. In the absence of interactions the cage is insulating due to destructive interference. We find that the cage stays insulating up to a critical value of the pump strength in the presence of mean-field interactions, while the quantum regime induces particle pair transport and weak conductance below the critical pump strength. A swift crossover from the quantum into the classical regime upon further pump strength increase is observed. We solve the time-dependent master equations for the density matrix of the many-body problem in the classical, pure quantum, and pseudoclassical regimes. We start with an empty cage and switch on driving. We characterize the transient dynamics, and the complexity of the resulting steady states and attractors. Our results can be readily realized using experimental platforms involving interacting ultracold atoms, superconducting circuits, and photons on fine-tuned optical lattices.