Instability and particle current control of a parametrically driven Bose-Einstein condensate in a ring-shaped lattice

We investigate the dynamics of a Bose-Einstein condensate in a one-dimensional ring-shaped lattice with the Peierls phase and site-dependent modulations, where the condensate is confined in a single deep trap and the interparticle interaction strength is modulated by a time-periodic driving field. The system has a finite spectrum, which limits the excitation regimes, and the Peierls phase typically induces imbalanced complex hopping amplitudes in each direction, leading to nonzero net particle currents along the lattice chain, which can hold nearly persistent even when the driving field is turned off after half of the period. The configuration provides a specific way for the coherent control of particle currents in many-body quantum systems with the help of an external driving field, and promotes the possible applications in future close-loop atom circuits.
Comment: 9 pages, 5 figures