Wave Function Renormalization Effects in Resonantly Enhanced Tunneling
  We study the time evolution of ultra-cold atoms in an accelerated optical lattice. For a Bose- Einstein condensate with a narrow quasi-momentum distribution in a shallow optical lattice the decay of the survival probability in the ground band has a step-like structure. In this regime we establish a connection between the wave function renormalization parameter Z introduced in [Phys. Rev. Lett. 86, 2699 (2001)] to characterize non-exponential decay and the phenomenon of resonantly enhanced tunneling, where the decay rate is peaked for particular values of the lattice depth and the accelerating force. 
N. L\"orch, F. V. Pepe, H. Lignier, D. Ciampini, R. Mannella, O.   Morsch, E. Arimondo, P. Facchi, G. Florio, S. Pascazio, a...
quant-ph cond-mat.quant-gas