Self-sustained Josephson dynamics and self-trapping in supersolids

Abstract: We explore the self-sustained Josephson junction dynamics in dipolar supersolids, predicting the possibility of self-trapping alongside the experimentally observed Josephson oscillations [Biagioni, G. et al., Nature 629, 773 (2024)]. Using an asymmetric two-mode (ATM) model to describe a triangular dipolar supersolid, validated through Gross-Pitaevskii simulations, we demonstrate that the system's symmetry enables a consistent two-mode mapping despite the presence of seven droplets. Hence, the associated Hamiltonian allows us to straightforwardly determine the self-trapping regime. Additionally, we show that bringing the system into rotation preserves its ability to sustain the Josephson junction dynamics across its full range, and we assess the robustness of the ATM model under these conditions. We further find that the off-axis droplets move in the radial direction during the evolution in accordance with the size of the central droplet. Such movements do not interfere with the model predictions.