Resonance-assisted tunneling in three degrees of freedom without   discrete symmetry
  We study dynamical tunneling in a near-integrable Hamiltonian with three degrees of freedom. The model Hamiltonian does not have any discrete symmetry. Despite this lack of symmetry we show that the mixing of near-degenerate quantum states is due to dynamical tunneling mediated by the nonlinear resonances in the classical phase space. Identifying the key resonances allows us to suppress the dynamical tunneling via the addition of weak counter-resonant terms. 
Srihari Keshavamurthy