Manifold approach for a many-body Wannier-Stark system: localization and   chaos in energy space
  We study the resonant tunneling effect in a many-body Wannier-Stark system, realized by ultracold bosonic atoms in an optical lattice subjected to an external Stark force. The properties of the many-body system are effectively described in terms of upper-band excitation manifolds, which allow for the study of the transition between regular and quantum chaotic spectral statistics. We show that our system makes it possible to control the spectral statistics locally in energy space by the competition of the force and the interparticle interaction. By a time-dependent sweep of the Stark force the dynamics is reduced to a Landau-Zener problem in the single-particle setting. 
C. A. Parra-Murillo and S. Wimberger
cond-mat.quant-gas