Magnetic-induced chiral dynamics in an extended two-leg bosonic ladder

Abstract

The realization and detection of chiral physics with ultracold atomic gases provide a unique path
for the exploration of topological phases. Here, we show that the interplay of magnetic field and
interacting particles in an extended two-leg ladder leads to rich chiral Bloch dynamics. Considering
both the on-site contact interaction and nearest-neighbor interactions, the ground state and Bloch
dynamics of the system are studied analytically and numerically. When the system is in the ground
state, the threshold and phase diagram for the transition between zero-momentum state and plane-wave state are analytically obtained, showing the nearest-neighbor interactions along the legs and
rungs have opposite impact on the ground state transition, providing new opportunity to manipulate
the ground state transition. When the ladder is perturbated under an external linear force, chiral
dephasing of Bloch oscillations (BOs), i.e., symmetry breaking damped BOs (the damping rate
of BOs on one leg is larger than the other), are observed. This chirality is absent for vanishing
the magnetic field and atomic interaction. Particularly, the chirality of damped BOs is inversed
when the magnetic field (chiral current) is inversed. In addition, the damping of BOs induced
by different types of atomic interactions is different, and the strength and damping rate of BOs
initialized in different ground states are distinct, offering dynamic ways to detect the different
ground states. Furthermore, the persistent chiral Bloch oscillations observed in single particle case
is predicted analytically, which is a crucial requirement for observation and application of chiral BOs
in nonlinear regime. Our results provide an interesting path towards the exploration of topological
atomic superfluids.