Driven collective quantum tunneling of ultracold atoms in engineered optical lattices

Collective quantum tunneling of a Bose-Einstein condensate between two parts of an optical lattice separated by an energy barrier is theoretically investigated. We show that by a pulsewise change of the barrier height, it is possible to switch between a tunneling regime and a self-trapped one. This property of the system is explained by effectively reducing the nonlinear dynamics of the system to that of a particle moving in a double square well potential. The analysis is performed for both attractive and repulsive interatomic forces, and emphasizes the experimental relevance of our findings.