Unearthing wave-function renormalization effects in the time evolution of a Bose-Einstein condensate

We study the time evolution of a Bose-Einstein condensate in an accelerated optical lattice. When the condensate has a narrow quasi-momentum distribution and the optical lattice is shallow, the survival probability in the ground band exhibits a step-like structure. In this regime, we establish a connection between the wave-function renormalization parameter Z and the phenomenon of resonantly enhanced tunneling.