Resonance detuning mechanism for directing particle flow in ring lattices

We theoretically investigate the control of superfluid currents for ultracold gases confined in a ring lattice. The system is assumed to be in the presence of an artificial magnetic flux piercing the ring. By introducing ac-driven local energy shifts, we explore their potential to influence both the intensity and direction of supercurrents. Our analysis reveals that detuning of a resonance frequency associated with a photon-assisted tunneling process can be used to steer the current direction of particles in a ring. In particular, through a theoretical analysis of a three-site ring, we show that a detuning of the resonance frequency can couple the ground state to transporting Floquet states with current directions that depend on the sign of the detuning. This is achieved by ramping the ac-driving amplitude from zero, enabling the coupling of the ground state to the Floquet states. Moreover, our study shows that it is possible to change the direction of the current using either the detuning or the magnetic flux as a control parameter, thus providing extra freedom in the manipulation of the currents. These findings not only contribute to the understanding of transport behavior of matter waves in the presence of local energy shifts but also offer prospects for quantum control techniques in atomtronics and related fields.